sudo'nun zaman aşımını değiştirmek

[Chantre]

Terminalde "sudo" komutunu bir kere kullandığımız zaman 5 dakika içinde kullanacağımız diğer sudo komutları için şifre sormuyor. 5 dakika varsayılan değerdir. Değiştirmek için:

Kod Seç Genişlet

sudo visudo

Defaults evn_reset

geçen yeri bulun.

Kod Seç Genişlet

Defaults evn_reset , timestamp_timeout=x

x yerine zaman aşımının kaç dakika olmasını istiyorsanız onu yazın. Eğer zaman aşımı olmamasını istiyorsanız x yerine -1 yazın. Siz kapatana kadar sizden şifre istemesin. 

[sem]

Acaba oturum için mi zaman aşımı, aynı terminal için mi?

Denemem lazım... Eğer oturum için ise Diğer Dağıtım Sorunları bölümünde Yiğit Ateş'in sorduğu bir sorunun da cevabı oluyor sanırım aynı anda...

Teşekkürler paylaşım için...

[guestwho]

Terminalde "sudo" komutunu bir kere kullandığımız zaman 5 dakika içinde kullanacağımız diğer sudo komutları için şifre sormuyor. 5 dakika varsayılan değerdir. Değiştirmek için:

Kod Seç Genişlet

gksudo gedit /etc/sudoers

Defaults evn_reset

geçen yeri bulun.

Kod Seç Genişlet

Defaults evn_reset , timestamp_timeout=x

x yerine zaman aşımının kaç dakika olmasını istiyorsanız onu yazın. Eğer zaman aşımı olmamasını istiyorsanız x yerine -1 yazın. Siz kapatana kadar sizden şifre istemesin.

    Burada değişiklik yapılacak olan sözkonusu dosyanın ikili (binary) dosya olduğunun farkında mısın ? Şu dökümanları okuduktan sonra iletinde gerekli değişiklikleri yapmanı öneririm...

Kod Seç Genişlet

man sudoers
man visudo

[eribol]

[eribol@archbang ~]$ sudo cat /etc/sudoers
Parola:
## sudoers file.
##
## This file MUST be edited with the 'visudo' command as root.
## Failure to use 'visudo' may result in syntax or file permission errors
## that prevent sudo from running.
##
## See the sudoers man page for the details on how to write a sudoers file.
##

##
## Host alias specification
##
## Groups of machines. These may include host names (optionally with wildcards),
## IP addresses, network numbers or netgroups.
# Host_Alias   WEBSERVERS = www1, www2, www3

##
## User alias specification
##
## Groups of users.  These may consist of user names, uids, Unix groups,
## or netgroups.
# User_Alias   ADMINS = millert, dowdy, mikef

##
## Cmnd alias specification
##
## Groups of commands.  Often used to group related commands together.
# Cmnd_Alias   PROCESSES = /usr/bin/nice, /bin/kill, /usr/bin/renice, \
#              /usr/bin/pkill, /usr/bin/top

##
## Defaults specification
##
## You may wish to keep some of the following environment variables
## when running commands via sudo.
##
## Locale settings
# Defaults env_keep += "LANG LANGUAGE LINGUAS LC_* _XKB_CHARSET"

Pek ikilik dosya gibi durmuyor?

[sem]

Buralarda yapılan değişikliklere göre "sudo" dosyası tekrardan mı derleniyor ki acaba gibisinden düşündüm ben de ama "man sudoers" çok uzun geldi şu anda okuyabilmek için... @guestwho bir ip ucu verirseniz aramak için;

man sudoers > dosya

şeklinde "dosya" dan arama yapsak olur mu =)



Gerçi yeniden derlenmesinden ziyade parametre olarak okuması daha makul gibi ama?

[eribol]

Dosyayı root haklarıyla visudo komutuyla açın diye tavsiye ediliyor. Bu da dosyanın özel bir editörü olduğu imajını veriyor. Lakin dosyayı visudo ile açınca

root     22272  0.0  0.0   6080   632 pts/2    S+   00:17   0:00 visudo
root     22273  0.1  0.0   7132  1192 pts/2    S+   00:17   0:00 vi /etc/sudoers.tmp

Yani visudo komutu o arada vi komutuyla dosyayı açıyor. Dolayısıyla herhangi bir düzenleyici de iş görecektir.

[sem]

Dosyayı root haklarıyla visudo komutuyla açın diye tavsiye ediliyor. Bu da dosyanın özel bir editörü olduğu imajını veriyor. Lakin dosyayı visudo ile açınca

root     22272  0.0  0.0   6080   632 pts/2    S+   00:17   0:00 visudo
root     22273  0.1  0.0   7132  1192 pts/2    S+   00:17   0:00 vi /etc/sudoers.tmp

Yani visudo komutu o arada vi komutuyla dosyayı açıyor. Dolayısıyla herhangi bir düzenleyici de iş görecektir.

Benim iletime binaen dediyseniz bunları, benim demek istediğim yani "man sudoers" dosyasında ne gibi bir ibareden bu işlemin ikilik dosyayı etkilediğini ya da bunların sakıncalı olacağını anlamamız gerekiyor? Buna dair bir ipucu verirse arkadaş;

man sudoers > dosya

ile dosyaya aktardığımız bilgilerden ctrl + f ile arama yapabilelim gibisinden söylemiştim...

sudoers çok uzun o nedenle dedim:

Kod Seç Genişlet

SUDOERS(5)                                         MAINTENANCE COMMANDS                                         SUDOERS(5)



NAME
       sudoers - list of which users may execute what

DESCRIPTION
       The sudoers file is composed of two types of entries: aliases (basically variables) and user specifications (which
       specify who may run what).

       When multiple entries match for a user, they are applied in order.  Where there are multiple matches, the last
       match is used (which is not necessarily the most specific match).

       The sudoers grammar will be described below in Extended Backus-Naur Form (EBNF).  Don't despair if you don't know
       what EBNF is; it is fairly simple, and the definitions below are annotated.

   Quick guide to EBNF
       EBNF is a concise and exact way of describing the grammar of a language.  Each EBNF definition is made up of
       production rules.  E.g.,

        symbol ::= definition | alternate1 | alternate2 ...

       Each production rule references others and thus makes up a grammar for the language.  EBNF also contains the
       following operators, which many readers will recognize from regular expressions.  Do not, however, confuse them
       with "wildcard" characters, which have different meanings.

       ?   Means that the preceding symbol (or group of symbols) is optional.  That is, it may appear once or not at all.

       *   Means that the preceding symbol (or group of symbols) may appear zero or more times.

       +   Means that the preceding symbol (or group of symbols) may appear one or more times.

       Parentheses may be used to group symbols together.  For clarity, we will use single quotes ('') to designate what
       is a verbatim character string (as opposed to a symbol name).

   Aliases
       There are four kinds of aliases: User_Alias, Runas_Alias, Host_Alias and Cmnd_Alias.

        Alias ::= 'User_Alias'  User_Alias (':' User_Alias)* |
                  'Runas_Alias' Runas_Alias (':' Runas_Alias)* |
                  'Host_Alias'  Host_Alias (':' Host_Alias)* |
                  'Cmnd_Alias'  Cmnd_Alias (':' Cmnd_Alias)*

        User_Alias ::= NAME '=' User_List

        Runas_Alias ::= NAME '=' Runas_List

        Host_Alias ::= NAME '=' Host_List

        Cmnd_Alias ::= NAME '=' Cmnd_List

        NAME ::= [A-Z]([A-Z][0-9]_)*

       Each alias definition is of the form

        Alias_Type NAME = item1, item2, ...

       where Alias_Type is one of User_Alias, Runas_Alias, Host_Alias, or Cmnd_Alias.  A NAME is a string of uppercase
       letters, numbers, and underscore characters ('_').  A NAME must start with an uppercase letter.  It is possible to
       put several alias definitions of the same type on a single line, joined by a colon (':').  E.g.,

        Alias_Type NAME = item1, item2, item3 : NAME = item4, item5

       The definitions of what constitutes a valid alias member follow.

        User_List ::= User |
                      User ',' User_List

        User ::= '!'* user name |
                 '!'* '#'uid |
                 '!'* '%'group |
                 '!'* '+'netgroup |
                 '!'* '%:'nonunix_group |
                 '!'* User_Alias

       A User_List is made up of one or more user names, uids (prefixed with '#'), system groups (prefixed with '%'),
       netgroups (prefixed with '+') and User_Aliases.  Each list item may be prefixed with zero or more '!' operators.
       An odd number of '!' operators negate the value of the item; an even number just cancel each other out.

       A user name, group, netgroup or nonunix_group may be enclosed in double quotes to avoid the need for escaping
       special characters.  Alternately, special characters may be specified in escaped hex mode, e.g. \x20 for space.

       The nonunix_group syntax depends on the underlying implementation.  For instance, the QAS AD backend supports the
       following formats:

       ·   Group in the same domain: "Group Name"

       ·   Group in any domain: "Group Name@FULLY.QUALIFIED.DOMAIN"

       ·   Group SID: "S-1-2-34-5678901234-5678901234-5678901234-567"

       Note that quotes around group names are optional.  Unquoted strings must use a backslash (\) to escape spaces and
       the '@' symbol.

        Runas_List ::= Runas_Member |
                       Runas_Member ',' Runas_List

        Runas_Member ::= '!'* user name |
                         '!'* '#'uid |
                         '!'* '%'group |
                         '!'* +netgroup |
                         '!'* Runas_Alias

       A Runas_List is similar to a User_List except that instead of User_Aliases it can contain Runas_Aliases.  Note that
       user names and groups are matched as strings.  In other words, two users (groups) with the same uid (gid) are
       considered to be distinct.  If you wish to match all user names with the same uid (e.g. root and toor), you can use
       a uid instead (#0 in the example given).

        Host_List ::= Host |
                      Host ',' Host_List

        Host ::= '!'* host name |
                 '!'* ip_addr |
                 '!'* network(/netmask)? |
                 '!'* '+'netgroup |
                 '!'* Host_Alias

       A Host_List is made up of one or more host names, IP addresses, network numbers, netgroups (prefixed with '+') and
       other aliases.  Again, the value of an item may be negated with the '!' operator.  If you do not specify a netmask
       along with the network number, sudo will query each of the local host's network interfaces and, if the network
       number corresponds to one of the hosts's network interfaces, the corresponding netmask will be used.  The netmask
       may be specified either in standard IP address notation (e.g. 255.255.255.0 or ffff:ffff:ffff:ffff::), or CIDR
       notation (number of bits, e.g. 24 or 64).  A host name may include shell-style wildcards (see the Wildcards section
       below), but unless the host name command on your machine returns the fully qualified host name, you'll need to use
       the fqdn option for wildcards to be useful.  Note sudo only inspects actual network interfaces; this means that IP
       address 127.0.0.1 (localhost) will never match.  Also, the host name "localhost" will only match if that is the
       actual host name, which is usually only the case for non-networked systems.

        Cmnd_List ::= Cmnd |
                      Cmnd ',' Cmnd_List

        commandname ::= file name |
                        file name args |
                        file name '""'

        Cmnd ::= '!'* commandname |
                 '!'* directory |
                 '!'* "sudoedit" |
                 '!'* Cmnd_Alias

       A Cmnd_List is a list of one or more commandnames, directories, and other aliases.  A commandname is a fully
       qualified file name which may include shell-style wildcards (see the Wildcards section below).  A simple file name
       allows the user to run the command with any arguments he/she wishes.  However, you may also specify command line
       arguments (including wildcards).  Alternately, you can specify "" to indicate that the command may only be run
       without command line arguments.  A directory is a fully qualified path name ending in a '/'.  When you specify a
       directory in a Cmnd_List, the user will be able to run any file within that directory (but not in any
       subdirectories therein).

       If a Cmnd has associated command line arguments, then the arguments in the Cmnd must match exactly those given by
       the user on the command line (or match the wildcards if there are any).  Note that the following characters must be
       escaped with a '\' if they are used in command arguments: ',', ':', '=', '\'.  The special command "sudoedit" is
       used to permit a user to run sudo with the -e option (or as sudoedit).  It may take command line arguments just as
       a normal command does.

   Defaults
       Certain configuration options may be changed from their default values at runtime via one or more Default_Entry
       lines.  These may affect all users on any host, all users on a specific host, a specific user, a specific command,
       or commands being run as a specific user.  Note that per-command entries may not include command line arguments.
       If you need to specify arguments, define a Cmnd_Alias and reference that instead.

        Default_Type ::= 'Defaults' |
                         'Defaults' '@' Host_List |
                         'Defaults' ':' User_List |
                         'Defaults' '!' Cmnd_List |
                         'Defaults' '>' Runas_List

        Default_Entry ::= Default_Type Parameter_List

        Parameter_List ::= Parameter |
                           Parameter ',' Parameter_List

        Parameter ::= Parameter '=' Value |
                      Parameter '+=' Value |
                      Parameter '-=' Value |
                      '!'* Parameter

       Parameters may be flags, integer values, strings, or lists.  Flags are implicitly boolean and can be turned off via
       the '!'  operator.  Some integer, string and list parameters may also be used in a boolean context to disable them.
       Values may be enclosed in double quotes (") when they contain multiple words.  Special characters may be escaped
       with a backslash (\).

       Lists have two additional assignment operators, += and -=.  These operators are used to add to and delete from a
       list respectively.  It is not an error to use the -= operator to remove an element that does not exist in a list.

       Defaults entries are parsed in the following order: generic, host and user Defaults first, then runas Defaults and
       finally command defaults.

       See "SUDOERS OPTIONS" for a list of supported Defaults parameters.

   User Specification
        User_Spec ::= User_List Host_List '=' Cmnd_Spec_List \
                      (':' Host_List '=' Cmnd_Spec_List)*

        Cmnd_Spec_List ::= Cmnd_Spec |
                           Cmnd_Spec ',' Cmnd_Spec_List

        Cmnd_Spec ::= Runas_Spec? Tag_Spec* Cmnd

        Runas_Spec ::= '(' Runas_List? (':' Runas_List)? ')'

        Tag_Spec ::= ('NOPASSWD:' | 'PASSWD:' | 'NOEXEC:' | 'EXEC:' |
                      'SETENV:' | 'NOSETENV:' | 'LOG_INPUT:' | 'NOLOG_INPUT:' |
                      'LOG_OUTPUT:' | 'NOLOG_OUTPUT:')

       A user specification determines which commands a user may run (and as what user) on specified hosts.  By default,
       commands are run as root, but this can be changed on a per-command basis.

       The basic structure of a user specification is `who = where (as_whom) what'.  Let's break that down into its
       constituent parts:

   Runas_Spec
       A Runas_Spec determines the user and/or the group that a command may be run as.  A fully-specified Runas_Spec
       consists of two Runas_Lists (as defined above) separated by a colon (':') and enclosed in a set of parentheses.
       The first Runas_List indicates which users the command may be run as via sudo's -u option.  The second defines a
       list of groups that can be specified via sudo's -g option.  If both Runas_Lists are specified, the command may be
       run with any combination of users and groups listed in their respective Runas_Lists.  If only the first is
       specified, the command may be run as any user in the list but no -g option may be specified.  If the first
       Runas_List is empty but the second is specified, the command may be run as the invoking user with the group set to
       any listed in the Runas_List.  If no Runas_Spec is specified the command may be run as root and no group may be
       specified.

       A Runas_Spec sets the default for the commands that follow it.  What this means is that for the entry:

        dgb    boulder = (operator) /bin/ls, /bin/kill, /usr/bin/lprm

       The user dgb may run /bin/ls, /bin/kill, and /usr/bin/lprm -- but only as operator.  E.g.,

        $ sudo -u operator /bin/ls.

       It is also possible to override a Runas_Spec later on in an entry.  If we modify the entry like so:

        dgb    boulder = (operator) /bin/ls, (root) /bin/kill, /usr/bin/lprm

       Then user dgb is now allowed to run /bin/ls as operator, but  /bin/kill and /usr/bin/lprm as root.

       We can extend this to allow dgb to run /bin/ls with either the user or group set to operator:

        dgb    boulder = (operator : operator) /bin/ls, (root) /bin/kill, \
               /usr/bin/lprm

       In the following example, user tcm may run commands that access a modem device file with the dialer group.  Note
       that in this example only the group will be set, the command still runs as user tcm.

        tcm    boulder = (:dialer) /usr/bin/tip, /usr/bin/cu, \
               /usr/local/bin/minicom

   Tag_Spec
       A command may have zero or more tags associated with it.  There are eight possible tag values, NOPASSWD, PASSWD,
       NOEXEC, EXEC, SETENV, NOSETENV, LOG_INPUT, NOLOG_INPUT, LOG_OUTPUT and NOLOG_OUTPUT.  Once a tag is set on a Cmnd,
       subsequent Cmnds in the Cmnd_Spec_List, inherit the tag unless it is overridden by the opposite tag (i.e.: PASSWD
       overrides NOPASSWD and NOEXEC overrides EXEC).

       NOPASSWD and PASSWD

       By default, sudo requires that a user authenticate him or herself before running a command.  This behavior can be
       modified via the NOPASSWD tag.  Like a Runas_Spec, the NOPASSWD tag sets a default for the commands that follow it
       in the Cmnd_Spec_List.  Conversely, the PASSWD tag can be used to reverse things.  For example:

        ray    rushmore = NOPASSWD: /bin/kill, /bin/ls, /usr/bin/lprm

       would allow the user ray to run /bin/kill, /bin/ls, and /usr/bin/lprm as root on the machine rushmore without
       authenticating himself.  If we only want ray to be able to run /bin/kill without a password the entry would be:

        ray    rushmore = NOPASSWD: /bin/kill, PASSWD: /bin/ls, /usr/bin/lprm

       Note, however, that the PASSWD tag has no effect on users who are in the group specified by the exempt_group
       option.

       By default, if the NOPASSWD tag is applied to any of the entries for a user on the current host, he or she will be
       able to run sudo -l without a password.  Additionally, a user may only run sudo -v without a password if the
       NOPASSWD tag is present for all a user's entries that pertain to the current host.  This behavior may be overridden
       via the verifypw and listpw options.

       NOEXEC and EXEC

       If sudo has been compiled with noexec support and the underlying operating system supports it, the NOEXEC tag can
       be used to prevent a dynamically-linked executable from running further commands itself.

       In the following example, user aaron may run /usr/bin/more and /usr/bin/vi but shell escapes will be disabled.

        aaron  shanty = NOEXEC: /usr/bin/more, /usr/bin/vi

       See the "PREVENTING SHELL ESCAPES" section below for more details on how NOEXEC works and whether or not it will
       work on your system.

       SETENV and NOSETENV

       These tags override the value of the setenv option on a per-command basis.  Note that if SETENV has been set for a
       command, any environment variables set on the command line way are not subject to the restrictions imposed by
       env_check, env_delete, or env_keep.  As such, only trusted users should be allowed to set variables in this manner.
       If the command matched is ALL, the SETENV tag is implied for that command; this default may be overridden by use of
       the NOSETENV tag.

       LOG_INPUT and NOLOG_INPUT

       These tags override the value of the log_input option on a per-command basis.  For more information, see the
       description of log_input in the "SUDOERS OPTIONS" section below.

       LOG_OUTPUT and NOLOG_OUTPUT

       These tags override the value of the log_output option on a per-command basis.  For more information, see the
       description of log_output in the "SUDOERS OPTIONS" section below.

   Wildcards
       sudo allows shell-style wildcards (aka meta or glob characters) to be used in host names, path names and command
       line arguments in the sudoers file.  Wildcard matching is done via the POSIX glob(3) and fnmatch(3) routines.  Note
       that these are not regular expressions.

       *       Matches any set of zero or more characters.

       ?       Matches any single character.

       [...]   Matches any character in the specified range.

       [!...]  Matches any character not in the specified range.

       \x      For any character "x", evaluates to "x".  This is used to escape special characters such as: "*", "?", "[",
               and "}".

       POSIX character classes may also be used if your system's glob(3) and fnmatch(3) functions support them.  However,
       because the ':' character has special meaning in sudoers, it must be escaped.  For example:

           /bin/ls [[\:alpha\:]]*

       Would match any file name beginning with a letter.

       Note that a forward slash ('/') will not be matched by wildcards used in the path name.  When matching the command
       line arguments, however, a slash does get matched by wildcards.  This is to make a path like:

           /usr/bin/*

       match /usr/bin/who but not /usr/bin/X11/xterm.

   Exceptions to wildcard rules
       The following exceptions apply to the above rules:

       ""      If the empty string "" is the only command line argument in the sudoers entry it means that command is not
               allowed to be run with any arguments.

   Including other files from within sudoers
       It is possible to include other sudoers files from within the sudoers file currently being parsed using the
       #include and #includedir directives.

       This can be used, for example, to keep a site-wide sudoers file in addition to a local, per-machine file.  For the
       sake of this example the site-wide sudoers will be /etc/sudoers and the per-machine one will be /etc/sudoers.local.
       To include /etc/sudoers.local from within /etc/sudoers we would use the following line in /etc/sudoers:

           #include /etc/sudoers.local

       When sudo reaches this line it will suspend processing of the current file (/etc/sudoers) and switch to
       /etc/sudoers.local.  Upon reaching the end of /etc/sudoers.local, the rest of /etc/sudoers will be processed.
       Files that are included may themselves include other files.  A hard limit of 128 nested include files is enforced
       to prevent include file loops.

       The file name may include the %h escape, signifying the short form of the host name.  I.e., if the machine's host
       name is "xerxes", then

       #include /etc/sudoers.%h

       will cause sudo to include the file /etc/sudoers.xerxes.

       The #includedir directive can be used to create a sudo.d directory that the system package manager can drop sudoers
       rules into as part of package installation.  For example, given:

       #includedir /etc/sudoers.d

       sudo will read each file in /etc/sudoers.d, skipping file names that end in ~ or contain a . character to avoid
       causing problems with package manager or editor temporary/backup files.  Files are parsed in sorted lexical order.
       That is, /etc/sudoers.d/01_first will be parsed before /etc/sudoers.d/10_second.  Be aware that because the sorting
       is lexical, not numeric, /etc/sudoers.d/1_whoops would be loaded after /etc/sudoers.d/10_second.  Using a
       consistent number of leading zeroes in the file names can be used to avoid such problems.

       Note that unlike files included via #include, visudo will not edit the files in a #includedir directory unless one
       of them contains a syntax error.  It is still possible to run visudo with the -f flag to edit the files directly.

   Other special characters and reserved words
       The pound sign ('#') is used to indicate a comment (unless it is part of a #include directive or unless it occurs
       in the context of a user name and is followed by one or more digits, in which case it is treated as a uid).  Both
       the comment character and any text after it, up to the end of the line, are ignored.

       The reserved word ALL is a built-in alias that always causes a match to succeed.  It can be used wherever one might
       otherwise use a Cmnd_Alias, User_Alias, Runas_Alias, or Host_Alias.  You should not try to define your own alias
       called ALL as the built-in alias will be used in preference to your own.  Please note that using ALL can be
       dangerous since in a command context, it allows the user to run any command on the system.

       An exclamation point ('!') can be used as a logical not operator both in an alias and in front of a Cmnd.  This
       allows one to exclude certain values.  Note, however, that using a ! in conjunction with the built-in ALL alias to
       allow a user to run "all but a few" commands rarely works as intended (see SECURITY NOTES below).

       Long lines can be continued with a backslash ('\') as the last character on the line.

       Whitespace between elements in a list as well as special syntactic characters in a User Specification ('=', ':',
       '(', ')') is optional.

       The following characters must be escaped with a backslash ('\') when used as part of a word (e.g. a user name or
       host name): '@', '!', '=', ':', ',', '(', ')', '\'.

SUDOERS OPTIONS
       sudo's behavior can be modified by Default_Entry lines, as explained earlier.  A list of all supported Defaults
       parameters, grouped by type, are listed below.

       Boolean Flags:

       always_set_home If enabled, sudo will set the HOME environment variable to the home directory of the target user
                       (which is root unless the -u option is used).  This effectively means that the -H option is always
                       implied.  Note that HOME is already set when the the env_reset option is enabled, so
                       always_set_home is only effective for configurations where env_reset is disabled.  This flag is off
                       by default.

       authenticate    If set, users must authenticate themselves via a password (or other means of authentication) before
                       they may run commands.  This default may be overridden via the PASSWD and NOPASSWD tags.  This flag
                       is on by default.

       closefrom_override
                       If set, the user may use sudo's -C option which overrides the default starting point at which sudo
                       begins closing open file descriptors.  This flag is off by default.

       compress_io     If set, and sudo is configured to log a command's input or output, the I/O logs will be compressed
                       using zlib.  This flag is on by default when sudo is compiled with zlib support.

       env_editor      If set, visudo will use the value of the EDITOR or VISUAL environment variables before falling back
                       on the default editor list.  Note that this may create a security hole as it allows the user to run
                       any arbitrary command as root without logging.  A safer alternative is to place a colon-separated
                       list of editors in the editor variable.  visudo will then only use the EDITOR or VISUAL if they
                       match a value specified in editor.  This flag is on by default.

       env_reset       If set, sudo will reset the environment to only contain the LOGNAME, MAIL, SHELL, USER, USERNAME
                       and the SUDO_* variables.  Any variables in the caller's environment that match the env_keep and
                       env_check lists are then added.  The default contents of the env_keep and env_check lists are
                       displayed when sudo is run by root with the -V option.  If the secure_path option is set, its value
                       will be used for the PATH environment variable.  This flag is on by default.

       fast_glob       Normally, sudo uses the glob(3) function to do shell-style globbing when matching path names.
                       However, since it accesses the file system, glob(3) can take a long time to complete for some
                       patterns, especially when the pattern references a network file system that is mounted on demand
                       (automounted).  The fast_glob option causes sudo to use the fnmatch(3) function, which does not
                       access the file system to do its matching.  The disadvantage of fast_glob is that it is unable to
                       match relative path names such as ./ls or ../bin/ls.  This has security implications when path
                       names that include globbing characters are used with the negation operator, '!', as such rules can
                       be trivially bypassed.  As such, this option should not be used when sudoers contains rules that
                       contain negated path names which include globbing characters.  This flag is off by default.

       fqdn            Set this flag if you want to put fully qualified host names in the sudoers file.  I.e., instead of
                       myhost you would use myhost.mydomain.edu.  You may still use the short form if you wish (and even
                       mix the two).  Beware that turning on fqdn requires sudo to make DNS lookups which may make sudo
                       unusable if DNS stops working (for example if the machine is not plugged into the network).  Also
                       note that you must use the host's official name as DNS knows it.  That is, you may not use a host
                       alias (CNAME entry) due to performance issues and the fact that there is no way to get all aliases
                       from DNS.  If your machine's host name (as returned by the hostname command) is already fully
                       qualified you shouldn't need to set fqdn.  This flag is on by default.

       ignore_dot      If set, sudo will ignore '.' or '' (current dir) in the PATH environment variable; the PATH itself
                       is not modified.  This flag is off by default.

       ignore_local_sudoers
                       If set via LDAP, parsing of /etc/sudoers will be skipped.  This is intended for Enterprises that
                       wish to prevent the usage of local sudoers files so that only LDAP is used.  This thwarts the
                       efforts of rogue operators who would attempt to add roles to /etc/sudoers.  When this option is
                       present, /etc/sudoers does not even need to exist. Since this option tells sudo how to behave when
                       no specific LDAP entries have been matched, this sudoOption is only meaningful for the cn=defaults
                       section.  This flag is off by default.

       insults         If set, sudo will insult users when they enter an incorrect password.  This flag is off by default.

       log_host        If set, the host name will be logged in the (non-syslog) sudo log file.  This flag is off by
                       default.

       log_year        If set, the four-digit year will be logged in the (non-syslog) sudo log file.  This flag is off by
                       default.

       long_otp_prompt When validating with a One Time Password (OPT) scheme such as S/Key or OPIE, a two-line prompt is
                       used to make it easier to cut and paste the challenge to a local window.  It's not as pretty as the
                       default but some people find it more convenient.  This flag is off by default.

       mail_always     Send mail to the mailto user every time a users runs sudo.  This flag is off by default.

       mail_badpass    Send mail to the mailto user if the user running sudo does not enter the correct password.  This
                       flag is off by default.

       mail_no_host    If set, mail will be sent to the mailto user if the invoking user exists in the sudoers file, but
                       is not allowed to run commands on the current host.  This flag is off by default.

       mail_no_perms   If set, mail will be sent to the mailto user if the invoking user is allowed to use sudo but the
                       command they are trying is not listed in their sudoers file entry or is explicitly denied.  This
                       flag is off by default.

       mail_no_user    If set, mail will be sent to the mailto user if the invoking user is not in the sudoers file.  This
                       flag is on by default.

       noexec          If set, all commands run via sudo will behave as if the NOEXEC tag has been set, unless overridden
                       by a EXEC tag.  See the description of NOEXEC and EXEC below as well as the "PREVENTING SHELL
                       ESCAPES" section at the end of this manual.  This flag is off by default.

       path_info       Normally, sudo will tell the user when a command could not be found in their PATH environment
                       variable.  Some sites may wish to disable this as it could be used to gather information on the
                       location of executables that the normal user does not have access to.  The disadvantage is that if
                       the executable is simply not in the user's PATH, sudo will tell the user that they are not allowed
                       to run it, which can be confusing.  This flag is on by default.

       passprompt_override
                       The password prompt specified by passprompt will normally only be used if the password prompt
                       provided by systems such as PAM matches the string "Password:".  If passprompt_override is set,
                       passprompt will always be used.  This flag is off by default.

       preserve_groups By default, sudo will initialize the group vector to the list of groups the target user is in.
                       When preserve_groups is set, the user's existing group vector is left unaltered.  The real and
                       effective group IDs, however, are still set to match the target user.  This flag is off by default.

       pwfeedback      By default, sudo reads the password like most other Unix programs, by turning off echo until the
                       user hits the return (or enter) key.  Some users become confused by this as it appears to them that
                       sudo has hung at this point.  When pwfeedback is set, sudo will provide visual feedback when the
                       user presses a key.  Note that this does have a security impact as an onlooker may be able to
                       determine the length of the password being entered.  This flag is off by default.

       requiretty      If set, sudo will only run when the user is logged in to a real tty.  When this flag is set, sudo
                       can only be run from a login session and not via other means such as cron(8) or cgi-bin scripts.
                       This flag is off by default.

       root_sudo       If set, root is allowed to run sudo too.  Disabling this prevents users from "chaining" sudo
                       commands to get a root shell by doing something like "sudo sudo /bin/sh".  Note, however, that
                       turning off root_sudo will also prevent root from running sudoedit.  Disabling root_sudo provides
                       no real additional security; it exists purely for historical reasons.  This flag is on by default.

       rootpw          If set, sudo will prompt for the root password instead of the password of the invoking user.  This
                       flag is off by default.

       runaspw         If set, sudo will prompt for the password of the user defined by the runas_default option (defaults
                       to root) instead of the password of the invoking user.  This flag is off by default.

       set_home        If enabled and sudo is invoked with the -s option the HOME environment variable will be set to the
                       home directory of the target user (which is root unless the -u option is used).  This effectively
                       makes the -s option imply -H.  Note that HOME is already set when the the env_reset option is
                       enabled, so set_home is only effective for configurations where env_reset is disabled.  This flag
                       is off by default.

       set_logname     Normally, sudo will set the LOGNAME, USER and USERNAME environment variables to the name of the
                       target user (usually root unless the -u option is given).  However, since some programs (including
                       the RCS revision control system) use LOGNAME to determine the real identity of the user, it may be
                       desirable to change this behavior.  This can be done by negating the set_logname option.  Note that
                       if the env_reset option has not been disabled, entries in the env_keep list will override the value
                       of set_logname.  This flag is on by default.

       setenv          Allow the user to disable the env_reset option from the command line.  Additionally, environment
                       variables set via the command line are not subject to the restrictions imposed by env_check,
                       env_delete, or env_keep.  As such, only trusted users should be allowed to set variables in this
                       manner.  This flag is off by default.

       shell_noargs    If set and sudo is invoked with no arguments it acts as if the -s option had been given.  That is,
                       it runs a shell as root (the shell is determined by the SHELL environment variable if it is set,
                       falling back on the shell listed in the invoking user's /etc/passwd entry if not).  This flag is
                       off by default.

       stay_setuid     Normally, when sudo executes a command the real and effective UIDs are set to the target user (root
                       by default).  This option changes that behavior such that the real UID is left as the invoking
                       user's UID.  In other words, this makes sudo act as a setuid wrapper.  This can be useful on
                       systems that disable some potentially dangerous functionality when a program is run setuid.  This
                       option is only effective on systems with either the setreuid() or setresuid() function.  This flag
                       is off by default.

       targetpw        If set, sudo will prompt for the password of the user specified by the -u option (defaults to root)
                       instead of the password of the invoking user.  In addition, the timestamp file name will include
                       the target user's name.  Note that this flag precludes the use of a uid not listed in the passwd
                       database as an argument to the -u option.  This flag is off by default.

       log_input       If set, sudo will run the command in a pseudo tty and log all user input.  If the standard input is
                       not connected to the user's tty, due to I/O redirection or because the command is part of a
                       pipeline, that input is also captured and stored in a separate log file.

                       Input is logged to the /var/log/sudo-io directory using a unique session ID that is included in the
                       normal sudo log line, prefixed with TSID=.

       log_output      If set, sudo will run the command in a pseudo tty and log all output that is sent to the screen,
                       similar to the script(1) command.  If the standard output or standard error is not connected to the
                       user's tty, due to I/O redirection or because the command is part of a pipeline, that output is
                       also captured and stored in separate log files.

                       Output is logged to the /var/log/sudo-io directory using a unique session ID that is included in
                       the normal sudo log line, prefixed with TSID=.

                       Output logs may be viewed with the sudoreplay(8) utility, which can also be used to list or search
                       the available logs.

       tty_tickets     If set, users must authenticate on a per-tty basis.  With this flag enabled, sudo will use a file
                       named for the tty the user is logged in on in the user's time stamp directory.  If disabled, the
                       time stamp of the directory is used instead.  This flag is on by default.

       umask_override  If set, sudo will set the umask as specified by sudoers without modification.  This makes it
                       possible to specify a more permissive umask in sudoers than the user's own umask and matches
                       historical behavior.  If umask_override is not set, sudo will set the umask to be the union of the
                       user's umask and what is specified in sudoers.  This flag is off by default.

       use_pty         If set, sudo will run the command in a pseudo-pty even if no I/O logging is being gone.  A
                       malicious program run under sudo could conceivably fork a background process that retains to the
                       user's terminal device after the main program has finished executing.  Use of this option will make
                       that impossible.

       visiblepw       By default, sudo will refuse to run if the user must enter a password but it is not possible to
                       disable echo on the terminal.  If the visiblepw flag is set, sudo will prompt for a password even
                       when it would be visible on the screen.  This makes it possible to run things like "rsh somehost
                       sudo ls" since rsh(1) does not allocate a tty.  This flag is off by default.

       Integers:

       closefrom       Before it executes a command, sudo will close all open file descriptors other than standard input,
                       standard output and standard error (ie: file descriptors 0-2).  The closefrom option can be used to
                       specify a different file descriptor at which to start closing.  The default is 3.

       passwd_tries    The number of tries a user gets to enter his/her password before sudo logs the failure and exits.
                       The default is 3.

       Integers that can be used in a boolean context:

       loglinelen      Number of characters per line for the file log.  This value is used to decide when to wrap lines
                       for nicer log files.  This has no effect on the syslog log file, only the file log.  The default is
                       80 (use 0 or negate the option to disable word wrap).

       passwd_timeout  Number of minutes before the sudo password prompt times out, or 0 for no timeout.  The timeout may
                       include a fractional component if minute granularity is insufficient, for example 2.5.  The default
                       is 0.

       timestamp_timeout
                       Number of minutes that can elapse before sudo will ask for a passwd again.  The timeout may include
                       a fractional component if minute granularity is insufficient, for example 2.5.  The default is 15.
                       Set this to 0 to always prompt for a password.  If set to a value less than 0 the user's timestamp
                       will never expire.  This can be used to allow users to create or delete their own timestamps via
                       sudo -v and sudo -k respectively.

       umask           Umask to use when running the command.  Negate this option or set it to 0777 to preserve the user's
                       umask.  The actual umask that is used will be the union of the user's umask and 0022.  This
                       guarantees that sudo never lowers the umask when running a command.  Note on systems that use PAM,
                       the default PAM configuration may specify its own umask which will override the value set in
                       sudoers.

       Strings:

       badpass_message Message that is displayed if a user enters an incorrect password.  The default is Sorry, try again.
                       unless insults are enabled.

       editor          A colon (':') separated list of editors allowed to be used with visudo.  visudo will choose the
                       editor that matches the user's EDITOR environment variable if possible, or the first editor in the
                       list that exists and is executable.  The default is "/usr/bin/editor".

       mailsub         Subject of the mail sent to the mailto user. The escape %h will expand to the host name of the
                       machine.  Default is *** SECURITY information for %h ***.

       noexec_file     Path to a shared library containing dummy versions of the execv(), execve() and fexecve() library
                       functions that just return an error.  This is used to implement the noexec functionality on systems
                       that support LD_PRELOAD or its equivalent.  Defaults to /usr/lib/sudo/sudo_noexec.so.

       passprompt      The default prompt to use when asking for a password; can be overridden via the -p option or the
                       SUDO_PROMPT environment variable.  The following percent (`%') escapes are supported:

                       %H  expanded to the local host name including the domain name (on if the machine's host name is
                           fully qualified or the fqdn option is set)

                       %h  expanded to the local host name without the domain name

                       %p  expanded to the user whose password is being asked for (respects the rootpw, targetpw and
                           runaspw flags in sudoers)

                       %U  expanded to the login name of the user the command will be run as (defaults to root)

                       %u  expanded to the invoking user's login name

                       %%  two consecutive % characters are collapsed into a single % character

                       The default value is [sudo] password for %p: .

       runas_default   The default user to run commands as if the -u option is not specified on the command line.  This
                       defaults to root.  Note that if runas_default is set it must occur before any Runas_Alias
                       specifications.

       syslog_badpri   Syslog priority to use when user authenticates unsuccessfully.  Defaults to alert.

       syslog_goodpri  Syslog priority to use when user authenticates successfully.  Defaults to notice.

       sudoers_locale  Locale to use when parsing the sudoers file.  Note that changing the locale may affect how sudoers
                       is interpreted.  Defaults to "C".

       timestampdir    The directory in which sudo stores its timestamp files.  The default is /var/lib/sudo.

       timestampowner  The owner of the timestamp directory and the timestamps stored therein.  The default is root.

       Strings that can be used in a boolean context:

       askpass     The askpass option specifies the fully qualified path to a helper program used to read the user's
                   password when no terminal is available.  This may be the case when sudo is executed from a graphical
                   (as opposed to text-based) application.  The program specified by askpass should display the argument
                   passed to it as the prompt and write the user's password to the standard output.  The value of askpass
                   may be overridden by the SUDO_ASKPASS environment variable.

       env_file    The env_file options specifies the fully qualified path to a file containing variables to be set in the
                   environment of the program being run.  Entries in this file should either be of the form VARIABLE=value
                   or export VARIABLE=value.  The value may optionally be surrounded by single or double quotes.
                   Variables in this file are subject to other sudo environment settings such as env_keep and env_check.

       exempt_group
                   Users in this group are exempt from password and PATH requirements.  This is not set by default.

       lecture     This option controls when a short lecture will be printed along with the password prompt.  It has the
                   following possible values:

                   always  Always lecture the user.

                   never   Never lecture the user.

                   once    Only lecture the user the first time they run sudo.

                   If no value is specified, a value of once is implied.  Negating the option results in a value of never
                   being used.  The default value is once.

       lecture_file
                   Path to a file containing an alternate sudo lecture that will be used in place of the standard lecture
                   if the named file exists.  By default, sudo uses a built-in lecture.

       listpw      This option controls when a password will be required when a user runs sudo with the -l option.  It has
                   the following possible values:

                   all     All the user's sudoers entries for the current host must have the NOPASSWD flag set to avoid
                           entering a password.

                   always  The user must always enter a password to use the -l option.

                   any     At least one of the user's sudoers entries for the current host must have the NOPASSWD flag set
                           to avoid entering a password.

                   never   The user need never enter a password to use the -l option.

                   If no value is specified, a value of any is implied.  Negating the option results in a value of never
                   being used.  The default value is any.

       logfile     Path to the sudo log file (not the syslog log file).  Setting a path turns on logging to a file;
                   negating this option turns it off.  By default, sudo logs via syslog.

       mailerflags Flags to use when invoking mailer. Defaults to -t.

       mailerpath  Path to mail program used to send warning mail.  Defaults to the path to sendmail found at configure
                   time.

       mailfrom    Address to use for the "from" address when sending warning and error mail.  The address should be
                   enclosed in double quotes (") to protect against sudo interpreting the @ sign.  Defaults to the name of
                   the user running sudo.

       mailto      Address to send warning and error mail to.  The address should be enclosed in double quotes (") to
                   protect against sudo interpreting the @ sign.  Defaults to root.

       secure_path Path used for every command run from sudo.  If you don't trust the people running sudo to have a sane
                   PATH environment variable you may want to use this.  Another use is if you want to have the "root path"
                   be separate from the "user path."  Users in the group specified by the exempt_group option are not
                   affected by secure_path.  This option is set to
                   F</usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/X11R6/bin> by default.

       syslog      Syslog facility if syslog is being used for logging (negate to disable syslog logging).  Defaults to
                   authpriv.

       verifypw    This option controls when a password will be required when a user runs sudo with the -v option.  It has
                   the following possible values:

                   all     All the user's sudoers entries for the current host must have the NOPASSWD flag set to avoid
                           entering a password.

                   always  The user must always enter a password to use the -v option.

                   any     At least one of the user's sudoers entries for the current host must have the NOPASSWD flag set
                           to avoid entering a password.

                   never   The user need never enter a password to use the -v option.

                   If no value is specified, a value of all is implied.  Negating the option results in a value of never
                   being used.  The default value is all.

       Lists that can be used in a boolean context:

       env_check       Environment variables to be removed from the user's environment if the variable's value contains %
                       or / characters.  This can be used to guard against printf-style format vulnerabilities in poorly-
                       written programs.  The argument may be a double-quoted, space-separated list or a single value
                       without double-quotes.  The list can be replaced, added to, deleted from, or disabled by using the
                       =, +=, -=, and ! operators respectively.  Regardless of whether the env_reset option is enabled or
                       disabled, variables specified by env_check will be preserved in the environment if they pass the
                       aforementioned check.  The default list of environment variables to check is displayed when sudo is
                       run by root with the -V option.

       env_delete      Environment variables to be removed from the user's environment when the env_reset option is not in
                       effect.  The argument may be a double-quoted, space-separated list or a single value without
                       double-quotes.  The list can be replaced, added to, deleted from, or disabled by using the =, +=,
                       -=, and ! operators respectively.  The default list of environment variables to remove is displayed
                       when sudo is run by root with the -V option.  Note that many operating systems will remove
                       potentially dangerous variables from the environment of any setuid process (such as sudo).

       env_keep        Environment variables to be preserved in the user's environment when the env_reset option is in
                       effect.  This allows fine-grained control over the environment sudo-spawned processes will receive.
                       The argument may be a double-quoted, space-separated list or a single value without double-quotes.
                       The list can be replaced, added to, deleted from, or disabled by using the =, +=, -=, and !
                       operators respectively.  The default list of variables to keep is displayed when sudo is run by
                       root with the -V option.

       When logging via syslog(3), sudo accepts the following values for the syslog facility (the value of the syslog
       Parameter): authpriv (if your OS supports it), auth, daemon, user, local0, local1, local2, local3, local4, local5,
       local6, and local7.  The following syslog priorities are supported: alert, crit, debug, emerg, err, info, notice,
       and warning.

FILES
       /etc/sudoers            List of who can run what

       /etc/group              Local groups file

       /etc/netgroup           List of network groups

       /var/log/sudo-io        I/O log files

EXAMPLES
       Below are example sudoers entries.  Admittedly, some of these are a bit contrived.  First, we allow a few
       environment variables to pass and then define our aliases:

        # Run X applications through sudo; HOME is used to find the
        # .Xauthority file.  Note that other programs use HOME to find
        # configuration files and this may lead to privilege escalation!
        Defaults env_keep += "DISPLAY HOME"

        # User alias specification
        User_Alias     FULLTIMERS = millert, mikef, dowdy
        User_Alias     PARTTIMERS = bostley, jwfox, crawl
        User_Alias     WEBMASTERS = will, wendy, wim

        # Runas alias specification
        Runas_Alias    OP = root, operator
        Runas_Alias    DB = oracle, sybase
        Runas_Alias    ADMINGRP = adm, oper

        # Host alias specification
        Host_Alias     SPARC = bigtime, eclipse, moet, anchor :\
                       SGI = grolsch, dandelion, black :\
                       ALPHA = widget, thalamus, foobar :\
                       HPPA = boa, nag, python
        Host_Alias     CUNETS = 128.138.0.0/255.255.0.0
        Host_Alias     CSNETS = 128.138.243.0, 128.138.204.0/24, 128.138.242.0
        Host_Alias     SERVERS = master, mail, www, ns
        Host_Alias     CDROM = orion, perseus, hercules

        # Cmnd alias specification
        Cmnd_Alias     DUMPS = /usr/bin/mt, /usr/sbin/dump, /usr/sbin/rdump,\
                               /usr/sbin/restore, /usr/sbin/rrestore
        Cmnd_Alias     KILL = /usr/bin/kill
        Cmnd_Alias     PRINTING = /usr/sbin/lpc, /usr/bin/lprm
        Cmnd_Alias     SHUTDOWN = /usr/sbin/shutdown
        Cmnd_Alias     HALT = /usr/sbin/halt
        Cmnd_Alias     REBOOT = /usr/sbin/reboot
        Cmnd_Alias     SHELLS = /usr/bin/sh, /usr/bin/csh, /usr/bin/ksh, \
                                /usr/local/bin/tcsh, /usr/bin/rsh, \
                                /usr/local/bin/zsh
        Cmnd_Alias     SU = /usr/bin/su
        Cmnd_Alias     PAGERS = /usr/bin/more, /usr/bin/pg, /usr/bin/less

       Here we override some of the compiled in default values.  We want sudo to log via syslog(3) using the auth facility
       in all cases.  We don't want to subject the full time staff to the sudo lecture, user millert need not give a
       password, and we don't want to reset the LOGNAME, USER or USERNAME environment variables when running commands as
       root.  Additionally, on the machines in the SERVERS Host_Alias, we keep an additional local log file and make sure
       we log the year in each log line since the log entries will be kept around for several years.  Lastly, we disable
       shell escapes for the commands in the PAGERS Cmnd_Alias (/usr/bin/more, /usr/bin/pg and /usr/bin/less).

        # Override built-in defaults
        Defaults               syslog=auth
        Defaults>root          !set_logname
        Defaults:FULLTIMERS    !lecture
        Defaults:millert       !authenticate
        Defaults@SERVERS       log_year, logfile=/var/log/sudo.log
        Defaults!PAGERS        noexec

       The User specification is the part that actually determines who may run what.

        root           ALL = (ALL) ALL
        %wheel         ALL = (ALL) ALL

       We let root and any user in group wheel run any command on any host as any user.

        FULLTIMERS     ALL = NOPASSWD: ALL

       Full time sysadmins (millert, mikef, and dowdy) may run any command on any host without authenticating themselves.

        PARTTIMERS     ALL = ALL

       Part time sysadmins (bostley, jwfox, and crawl) may run any command on any host but they must authenticate
       themselves first (since the entry lacks the NOPASSWD tag).

        jack           CSNETS = ALL

       The user jack may run any command on the machines in the CSNETS alias (the networks 128.138.243.0, 128.138.204.0,
       and 128.138.242.0).  Of those networks, only 128.138.204.0 has an explicit netmask (in CIDR notation) indicating it
       is a class C network.  For the other networks in CSNETS, the local machine's netmask will be used during matching.

        lisa           CUNETS = ALL

       The user lisa may run any command on any host in the CUNETS alias (the class B network 128.138.0.0).

        operator       ALL = DUMPS, KILL, SHUTDOWN, HALT, REBOOT, PRINTING,\
                       sudoedit /etc/printcap, /usr/oper/bin/

       The operator user may run commands limited to simple maintenance.  Here, those are commands related to backups,
       killing processes, the printing system, shutting down the system, and any commands in the directory /usr/oper/bin/.

        joe            ALL = /usr/bin/su operator

       The user joe may only su(1) to operator.

        pete           HPPA = /usr/bin/passwd [A-Za-z]*, !/usr/bin/passwd root

        %opers         ALL = (: ADMINGRP) /usr/sbin/

       Users in the opers group may run commands in /usr/sbin/ as themselves with any group in the ADMINGRP Runas_Alias
       (the adm and oper groups).

       The user pete is allowed to change anyone's password except for root on the HPPA machines.  Note that this assumes
       passwd(1) does not take multiple user names on the command line.

        bob            SPARC = (OP) ALL : SGI = (OP) ALL

       The user bob may run anything on the SPARC and SGI machines as any user listed in the OP Runas_Alias (root and
       operator).

        jim            +biglab = ALL

       The user jim may run any command on machines in the biglab netgroup.  sudo knows that "biglab" is a netgroup due to
       the '+' prefix.

        +secretaries   ALL = PRINTING, /usr/bin/adduser, /usr/bin/rmuser

       Users in the secretaries netgroup need to help manage the printers as well as add and remove users, so they are
       allowed to run those commands on all machines.

        fred           ALL = (DB) NOPASSWD: ALL

       The user fred can run commands as any user in the DB Runas_Alias (oracle or sybase) without giving a password.

        john           ALPHA = /usr/bin/su [!-]*, !/usr/bin/su *root*

       On the ALPHA machines, user john may su to anyone except root but he is not allowed to specify any options to the
       su(1) command.

        jen            ALL, !SERVERS = ALL

       The user jen may run any command on any machine except for those in the SERVERS Host_Alias (master, mail, www and
       ns).

        jill           SERVERS = /usr/bin/, !SU, !SHELLS

       For any machine in the SERVERS Host_Alias, jill may run any commands in the directory /usr/bin/ except for those
       commands belonging to the SU and SHELLS Cmnd_Aliases.

        steve          CSNETS = (operator) /usr/local/op_commands/

       The user steve may run any command in the directory /usr/local/op_commands/ but only as user operator.

        matt           valkyrie = KILL

       On his personal workstation, valkyrie, matt needs to be able to kill hung processes.

        WEBMASTERS     www = (www) ALL, (root) /usr/bin/su www

       On the host www, any user in the WEBMASTERS User_Alias (will, wendy, and wim), may run any command as user www
       (which owns the web pages) or simply su(1) to www.

        ALL            CDROM = NOPASSWD: /sbin/umount /CDROM,\
                       /sbin/mount -o nosuid\,nodev /dev/cd0a /CDROM

       Any user may mount or unmount a CD-ROM on the machines in the CDROM Host_Alias (orion, perseus, hercules) without
       entering a password.  This is a bit tedious for users to type, so it is a prime candidate for encapsulating in a
       shell script.

SECURITY NOTES
       It is generally not effective to "subtract" commands from ALL using the '!' operator.  A user can trivially
       circumvent this by copying the desired command to a different name and then executing that.  For example:

           bill        ALL = ALL, !SU, !SHELLS

       Doesn't really prevent bill from running the commands listed in SU or SHELLS since he can simply copy those
       commands to a different name, or use a shell escape from an editor or other program.  Therefore, these kind of
       restrictions should be considered advisory at best (and reinforced by policy).

       Furthermore, if the fast_glob option is in use, it is not possible to reliably negate commands where the path name
       includes globbing (aka wildcard) characters.  This is because the C library's fnmatch(3) function cannot resolve
       relative paths.  While this is typically only an inconvenience for rules that grant privileges, it can result in a
       security issue for rules that subtract or revoke privileges.

       For example, given the following sudoers entry:

        john   ALL = /usr/bin/passwd [a-zA-Z0-9]*, /usr/bin/chsh [a-zA-Z0-9]*,
             /usr/bin/chfn [a-zA-Z0-9]*, !/usr/bin/* root

       User john can still run /usr/bin/passwd root if fast_glob is enabled by changing to /usr/bin and running ./passwd
       root instead.

PREVENTING SHELL ESCAPES
       Once sudo executes a program, that program is free to do whatever it pleases, including run other programs.  This
       can be a security issue since it is not uncommon for a program to allow shell escapes, which lets a user bypass
       sudo's access control and logging.  Common programs that permit shell escapes include shells (obviously), editors,
       paginators, mail and terminal programs.

       There are two basic approaches to this problem:

       restrict  Avoid giving users access to commands that allow the user to run arbitrary commands.  Many editors have a
                 restricted mode where shell escapes are disabled, though sudoedit is a better solution to running editors
                 via sudo.  Due to the large number of programs that offer shell escapes, restricting users to the set of
                 programs that do not if often unworkable.

       noexec    Many systems that support shared libraries have the ability to override default library functions by
                 pointing an environment variable (usually LD_PRELOAD) to an alternate shared library.  On such systems,
                 sudo's noexec functionality can be used to prevent a program run by sudo from executing any other
                 programs.  Note, however, that this applies only to native dynamically-linked executables.  Statically-
                 linked executables and foreign executables running under binary emulation are not affected.

                 To tell whether or not sudo supports noexec, you can run the following as root:

                     sudo -V | grep "dummy exec"

                 If the resulting output contains a line that begins with:

                     File containing dummy exec functions:

                 then sudo may be able to replace the exec family of functions in the standard library with its own that
                 simply return an error.  Unfortunately, there is no foolproof way to know whether or not noexec will work
                 at compile-time.  noexec should work on SunOS, Solaris, *BSD, Linux, IRIX, Tru64 UNIX, MacOS X, and HP-UX
                 11.x.  It is known not to work on AIX and UnixWare.  noexec is expected to work on most operating systems
                 that support the LD_PRELOAD environment variable.  Check your operating system's manual pages for the
                 dynamic linker (usually ld.so, ld.so.1, dyld, dld.sl, rld, or loader) to see if LD_PRELOAD is supported.

                 To enable noexec for a command, use the NOEXEC tag as documented in the User Specification section above.
                 Here is that example again:

                  aaron  shanty = NOEXEC: /usr/bin/more, /usr/bin/vi

                 This allows user aaron to run /usr/bin/more and /usr/bin/vi with noexec enabled.  This will prevent those
                 two commands from executing other commands (such as a shell).  If you are unsure whether or not your
                 system is capable of supporting noexec you can always just try it out and see if it works.

       Note that restricting shell escapes is not a panacea.  Programs running as root are still capable of many
       potentially hazardous operations (such as changing or overwriting files) that could lead to unintended privilege
       escalation.  In the specific case of an editor, a safer approach is to give the user permission to run sudoedit.

SEE ALSO
       rsh(1), su(1), fnmatch(3), glob(3), sudo(8), visudo(8)

CAVEATS
       The sudoers file should always be edited by the visudo command which locks the file and does grammatical checking.
       It is imperative that sudoers be free of syntax errors since sudo will not run with a syntactically incorrect
       sudoers file.

       When using netgroups of machines (as opposed to users), if you store fully qualified host name in the netgroup (as
       is usually the case), you either need to have the machine's host name be fully qualified as returned by the
       hostname command or use the fqdn option in sudoers.

BUGS
       If you feel you have found a bug in sudo, please submit a bug report at http://www.sudo.ws/sudo/bugs/

SUPPORT
       Limited free support is available via the sudo-users mailing list, see
       http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives.

DISCLAIMER
       sudo is provided ``AS IS'' and any express or implied warranties, including, but not limited to, the implied
       warranties of merchantability and fitness for a particular purpose are disclaimed.  See the LICENSE file
       distributed with sudo or http://www.sudo.ws/sudo/license.html for complete details.



1.7.4                                                  July 21, 2010                                            SUDOERS(5)

Benim iletime açıklama olarak söylemediyseniz pas geçebilirsiniz. İyi geceler.

[guestwho]

[eribol@archbang ~]$ sudo cat /etc/sudoers
Parola:
## sudoers file.
##
## This file MUST be edited with the 'visudo' command as root.
## Failure to use 'visudo' may result in syntax or file permission errors
## that prevent sudo from running.
##
## See the sudoers man page for the details on how to write a sudoers file.
##

##
## Host alias specification
##
## Groups of machines. These may include host names (optionally with wildcards),
## IP addresses, network numbers or netgroups.
# Host_Alias   WEBSERVERS = www1, www2, www3

##
## User alias specification
##
## Groups of users.  These may consist of user names, uids, Unix groups,
## or netgroups.
# User_Alias   ADMINS = millert, dowdy, mikef

##
## Cmnd alias specification
##
## Groups of commands.  Often used to group related commands together.
# Cmnd_Alias   PROCESSES = /usr/bin/nice, /bin/kill, /usr/bin/renice, \
#              /usr/bin/pkill, /usr/bin/top

##
## Defaults specification
##
## You may wish to keep some of the following environment variables
## when running commands via sudo.
##
## Locale settings
# Defaults env_keep += "LANG LANGUAGE LINGUAS LC_* _XKB_CHARSET"

Pek ikilik dosya gibi durmuyor?

    Güzel bir noktaya değinmişsin. Bir dosyayı "ikilik dosya" ya da "salt metin dosyası" yapan şey sözkonusu dosyanın içeriğinin "ASCII" karakter setinden oluşup oluşmaması durumu değildir. Ayrıca bir dosyanın ikili dosya olarak kabul görmesi için ille de içerisinde tuhaf karakterleri barındırması gerekmiyor. Burada asıl belirleyici unsur sözkonusu dosya içeriğinin "satır bazında" ya da "byte bazında" yorumlanıp yorumlanmaması durumudur. Demek istediğim bu dosyayı "Gedit" ile açarsan; evet bu dosya salt metin dosyasıdır, zira Gedit bu dosyayı "satır bazında" yorumlar. Lakin bu "sudoers" dosyasını "/usr/sbin/visudo" ile açarsan; bu dosya "byte bazında" yorumlandığı için bu süre zarfında "ikilik dosya" mahiyetindedir. Ayrıca "visudo" nun kendisi; "vi" ya da "nano" gibi metin düzenleyiciler ile karıştırılmamalı. Kaynak kodundan ne demek istediğimi anlayabilirsin:

http://www.opensource.apple.com/source/sudo/sudo-46/src/visudo.c

Dosyayı root haklarıyla visudo komutuyla açın diye tavsiye ediliyor. Bu da dosyanın özel bir editörü olduğu imajını veriyor. Lakin dosyayı visudo ile açınca

root     22272  0.0  0.0   6080   632 pts/2    S+   00:17   0:00 visudo
root     22273  0.1  0.0   7132  1192 pts/2    S+   00:17   0:00 vi /etc/sudoers.tmp

Yani visudo komutu o arada vi komutuyla dosyayı açıyor. Dolayısıyla herhangi bir düzenleyici de iş görecektir.

    Zaten herhangi bir metin düzenleyici "sudoers" dosyasında "visudo" gibi söz dizimi kontrolü yapamadığı için bu dosyanın "visudo" ile açılması gerekiyor... "sudoers" dosyasında tek bir boşluktan ötürü "sudo" komutunun kullanılamamasına yol açan hatalardan birkaçı:

https://bugs.launchpad.net/ubuntu/+source/sudo/+bug/501204
https://answers.launchpad.net/ubuntu/+source/sudo/+question/62080
http://ubuntuforums.org/showthread.php?t=494954

Buralarda yapılan değişikliklere göre "sudo" dosyası tekrardan mı derleniyor ki acaba gibisinden düşündüm ben de ama "man sudoers" çok uzun geldi şu anda okuyabilmek için... @guestwho bir ip ucu verirseniz aramak için;

man sudoers > dosya

şeklinde "dosya" dan arama yapsak olur mu =)



Gerçi yeniden derlenmesinden ziyade parametre olarak okuması daha makul gibi ama?

    "Derlenmiş dosyalar" ikilik dosya türlerinden yalnızca bir tanesidir. Demek istediğim "Gimp" ile oluşturulan ".png" resim dosyası , Audacity ile oluşturulan "ogg", "flac" gibi "ses dosyaları" da "ikilik dosya" ya örnek olarak gösterilebilir. Sözgelimi bir resim dosyasını düzenlerken bir şeyleri derlemek zorunda kalmıyoruz, öyle değil mi ? Yukarıda izah ettiğim gibi "ikilik dosya" demek; kısacası bir program tarafından "byte bazında" yorumlanan dosya demektir. "Salt metin dosyası" demekse bir program tarafından "satır bazında" yorumlanan dosya demektir. Burada önemli olan nokta dosyanın "yorumlanma sürecinde" baz alınan unsurdur. (Byte / Satır)

[barış]

En son sudoers dosyasında bir deneme yapmıştım sonra root olamadım bir daha :d Single user mode'da girince düzeltebildim ancak.

[sem]

O zaman bir dosyanın ikilik dosya olduğunu belirleyen kendisi olmuyor da ona yapılan işlem mi oluyor? Çünkü herhangi bir dosya herhangi bir program tarafından istenildiği taktirde ikilik istenildiği takidirde de "text" modunda açılıyor.

C bildiğinizi varsayarak; bir dosyayı açarken "fopen"   fonksiyonuna parametre olarak "t" ya da "b" gönderebiliriz... kopyalama fonksiyonu yazdığımızı düşünürsek "b" göndereceğiz, bir text dosyasını "b" ile açtığımızda o zaman dosya o programa göre ikilik dosya mı olacak? Byte byte ele alınacak çünkü...

İkilik dosyaları byte düzeyinde ele alınması değil de aslında bilgiyararın diline dönüştürülmüş dosyalar olduğunu biliyordum. Çünkü sonuçta bilgisayarın dili Binary yani ikilik sistem değil midir? Biz ikilik dosya derken yani bilgisayar diline çevrilmiş dosyalar olduğunu anlamıyor muyuz?

Konu dağıldı, guestwho'nun ilk mesajı bırakılarak "İkilik Dosya Nedir" tarzında bölünebilir belki konu... Sonra buraya bir bağlantı bırakabiliriz, konu burada tartışılıyor gibisinden... Arkadaşın cevabına göre çünkü sorularım olabilir benim daha =)

[guestwho]

Konu dağıldı, guestwho'nun ilk mesajı bırakılarak "İkilik Dosya Nedir" tarzında bölünebilir belki konu... Sonra buraya bir bağlantı bırakabiliriz, konu burada tartışılıyor gibisinden... Arkadaşın cevabına göre çünkü sorularım olabilir benim daha =)

    Aslında ben de konuyu dağıtmak istemem. Lakin burada olduğu gibi "sudoers" ya da benzeri hassas dosyalarda değişiklik yapılması gerektiği vakit, bazı temel kavramların bilincinde olmakta fayda var.

O zaman bir dosyanın ikilik dosya olduğunu belirleyen kendisi olmuyor da ona yapılan işlem mi oluyor? Çünkü herhangi bir dosya herhangi bir program tarafından istenildiği taktirde ikilik istenildiği takidirde de "text" modunda açılıyor.

    Dosya formatlarına anlam veren şey; dosya formatlarının "parser" ları yani çözümleyicileridir. Diyelim ki belli bir şablon (template) kullanarak "xyz" diye kendi dosya formatını oluşturdun ve bu dosya formatının kullanıcı tarafında bir anlam ifade etmesi için bir de bu dosya formatının "karakter (byte) dizilişini" çözümleyen bir "parser" geliştirdin. Senin geliştirmiş olduğun çözümleyici (parser) bu "xyz" dosyasını ayrıştırıp yorumlamak için "/n" (Windows'ta "/r" de gerekiyor) gibi satır sonu ifadelerini kullanıyorsa; (çözümleyici bu "xyz" dosyasına "salt metin" muamelesi yaptığı için) bu bir "salt metin" dosyasıdır.

    Şayet geliştirmiş olduğun "xyz" dosya formatının (bütünlüğünün noktası virgülüne tamlığından emin olmak açısından) içeriğindeki her bir karakterin (byte) ayrıştırılması gerekiyorsa çözümleyici "/n" (ya da "/r") gibi satır sonu ifadelerinin de sadece başka bir "byte" olduğunu varsayarak ("xyz" dosyasının içeriğindeki satır sonu ifadelerini görmezden gelip) bu dosya formatını bir bütün olarak ele almalıdır. Bu durumda çözümleyici "xyz" dosyasına "ikili dosya" muamelesi yaptığından ötürü bu "xyz" dosyası artık bir "ikili dosya" dır. Kısacası dosya formatlarını çözümleyicilerinden bağımsız olarak değerlendirmek doğru olmaz.

C bildiğinizi varsayarak; bir dosyayı açarken "fopen"   fonksiyonuna parametre olarak "t" ya da "b" gönderebiliriz... kopyalama fonksiyonu yazdığımızı düşünürsek "b" göndereceğiz, bir text dosyasını "b" ile açtığımızda o zaman dosya o programa göre ikilik dosya mı olacak? Byte byte ele alınacak çünkü...

İkilik dosyaları byte düzeyinde ele alınması değil de aslında bilgiyararın diline dönüştürülmüş dosyalar olduğunu biliyordum. Çünkü sonuçta bilgisayarın dili Binary yani ikilik sistem değil midir? Biz ikilik dosya derken yani bilgisayar diline çevrilmiş dosyalar olduğunu anlamıyor muyuz?

    Elbette donanım düzeyinde veriler "ikili sayı sistemi" ile temsil edilir ve işlenir. Lakin bu seviyede bizim bildiğimiz dosya tertipinden (tek boyutlu byte dizileri) söz edilemez. Özünde her şey verinin hangi düzeyde, nasıl ele alındığı ve nasıl işlendiğiyle ilgilidir.



    Sadece en üst seviyede; yani uygulama düzeyinde "salt metin dosyası" ve "ikili dosya" diye belirgin bir "veri tipi ayrımından" söz edilebilir. Daha düşük seviyede yani "çekirdek seviyesinde" böyle bir ayrımdan söz edilemez; bu seviyede her şey ikili dosya mahiyetindedir; daha doğrusu çekirdek seviyesinde her şey "boru" (pipe) mekanizmasındaki "byte akışından" (byte stream) ibarettir. Zira "Linux'te her şey dosyadır" prensibinden kasıt da budur.

    Konuyu daha karmaşık hale getirmek istemem, fakat bir salt metin dosyası uygulama düzeyinde bile (en üst seviyede) nihayetinde "sadece ASCII kodlarından oluşan" bir ikili dosya türevidir, çünkü ASCII karakter kodlaması özünde bir alt küme niteliğindedir, evrensel küme niteliğinde değildir. "İkili dosya" ise kısaca; "bit" lerin (0 ve 1 'lerin) yanyana dizilip karakterlerin "byte" olarak temsil edildiği dosya yapılanması demektir.