Troubleshooting tips and FAQ for Sudo
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Q) When I run configure, it says "C compiler cannot create executables".
A) This usually means you either don't have a working compiler. This
could be due to the lack of a license or that some component of the
compiler suite could not be found. Check config.log for clues as
to why this is happening. On many systems, compiler components live
in /usr/ccs/bin which may not be in your PATH environment variable.
Q) When I run configure, it says "sudo requires the 'ar' utility to build".
A) As part of the build process, sudo creates a temporary library containing
objects that are shared amongst the different sudo executables.
On Unix systems, the "ar" utility is used to do this. This error
indicates that "ar" is missing on your system. On Solaris systems,
you may need to install the SUNWbtool package. On other systems
"ar" may be included in the GNU binutils package.
Q) Sudo compiles and installs OK but when I try to run it I get:
/usr/local/bin/sudo must be owned by uid 0 and have the setuid bit set
A) Sudo must be setuid root to do its work. Either /usr/local/bin/sudo
is not owned by uid 0 or the setuid bit is not set. This should have
been done for you by "make install" but you can fix it manually by
running the following as root:
# chown root /usr/local/bin/sudo; chmod 4111 /usr/local/bin/sudo
Q) Sudo compiles and installs OK but when I try to run it I get:
effective uid is not 0, is /usr/local/bin/sudo on a file system with the
'nosuid' option set or an NFS file system without root privileges?
A) The owner and permissions on the sudo binary appear to be OK but when
sudo ran, the setuid bit did not have an effect. There are two common
causes for this. The first is that the file system the sudo binary
is located on is mounted with the 'nosuid' mount option, which disables
setuid binaries. The other is that sudo is installed on an NFS-mounted
file system that is exported without root privileges. By default, NFS
file systems are exported with uid 0 mapped to a non-privileged uid
(usually -2).
You need to do something like
`chmod 4111 /usr/local/bin/sudo'. Also, the file system sudo resides
on must *not* be mounted (or exported) with the nosuid option or sudo
will not be able to work. Another possibility is you may have '.' in
your $PATH before the directory containing sudo. If you are going
to have '.' in your path you should make sure it is at the end.
Q) Sudo never gives me a chance to enter a password using PAM, it just
says 'Sorry, try again.' three times and exits.
A) You didn't setup PAM to work with sudo. On RedHat Linux or Fedora
Core this generally means installing sample.pam as /etc/pam.d/sudo.
See the sample.pam file for hints on what to use for other Linux
systems.
Q) Sudo says 'Account expired or PAM config lacks an "account"
section for sudo, contact your system administrator' and exits
but I know my account has not expired.
A) Your PAM config lacks an "account" specification. On Linux this
usually means you are missing a line like:
account required pam_unix.so
in /etc/pam.d/sudo.
Q) Sudo is setup to log via syslog(3) but I'm not getting any log
messages.
A) Make sure you have an entry in your syslog.conf file to save
the sudo messages (see the sample.syslog.conf file). The default
log facility is authpriv (changeable via configure or in sudoers).
Don't forget to send a SIGHUP to your syslogd so that it re-reads
its conf file. Also, remember that syslogd does *not* create
log files, you need to create the file before syslogd will log
to it (ie: touch /var/log/sudo).
Note: the facility (e.g. "auth.debug") must be separated from the
destination (e.g. "/var/log/auth" or "@loghost") by
tabs, *not* spaces. This is a common error.
Q) When sudo asks me for my password it never accepts what I enter even
though I know I entered my password correctly.
A) If you are not using pam and your system uses shadow passwords,
it is possible that sudo didn't properly detect that shadow
passwords are in use. Take a look at the generated config.h
file and verify that the C function used for shadow password
look ups was detected. For instance, for SVR4-style shadow
passwords, HAVE_GETSPNAM should be defined (you can search for
the string "shadow passwords" in config.h with your editor).
Note that there is no define for 4.4BSD-based shadow passwords
since that just uses the standard getpw* routines.
Q) Can sudo use the ssh agent for authentication instead of asking
for the user's Unix password?
A) Not directly, but you can use a PAM module like pam_ssh_agent_auth
or pam_ssh for this purpose.
Q) I don't want the sudoers file in /etc, how can I specify where it
should go?
A) Use the --sysconfdir option to configure. Ie:
configure --sysconfdir=/dir/you/want/sudoers/in
Q) Can I put the sudoers file in NIS/NIS+ or do I have to have a
copy on each machine?
A) There is no support for making an NIS/NIS+ map/table out of
the sudoers file at this time. You can distribute the sudoers
file via rsync or rdist. It is also possible to NFS-mount the
sudoers file. If you use LDAP at your site you may be interested
in sudo's LDAP sudoers support, see the README.LDAP file and the
sudoers.ldap manual.
Q) I don't run sendmail on my machine. Does this mean that I cannot
use sudo?
A) No, you just need to disable mailing with a line like:
Defaults !mailerpath
in your sudoers file or run configure with the --without-sendmail
option.
Q) When I run visudo it uses vi as the editor and I hate vi. How
can I make it use another editor?
A) You can specify the editor to use in visudo in the sudoers file.
See the "editor" and "env_editor" entries in the sudoers manual.
The defaults can also be set at configure time using the
--with-editor and --with-env-editor configure options.
Q) Sudo appears to be removing some variables from my environment, why?
A) Sudo removes the following "dangerous" environment variables
to guard against shared library spoofing, shell voodoo, and
kerberos server spoofing.
IFS
LOCALDOMAIN
RES_OPTIONS
HOSTALIASES
NLSPATH
PATH_LOCALE
TERMINFO
TERMINFO_DIRS
TERMPATH
TERMCAP
ENV
BASH_ENV
LC_ (if it contains a '/' or '%')
LANG (if it contains a '/' or '%')
LANGUAGE (if it contains a '/' or '%')
LD_*
_RLD_*
SHLIB_PATH (HP-UX only)
LIBPATH (AIX only)
KRB5_CONFIG (kerb5 only)
VAR_ACE (SecurID only)
USR_ACE (SecurID only)
DLC_ACE (SecurID only)
Q) How can I keep sudo from asking for a password?
A) To specify this on a per-user (and per-command) basis, use the
'NOPASSWD' tag right before the command list in sudoers. See
the sudoers man page and sample.sudoers for details. To disable
passwords completely, add !authenticate" to the Defaults line
in /etc/sudoers. You can also turn off authentication on a
per-user or per-host basis using a user or host-specific Defaults
entry in sudoers. To hard-code the global default, you can
configure with the --without-passwd option.
Q) When I run configure, it dies with the following error:
"no acceptable cc found in $PATH".
A) /usr/ucb/cc was the only C compiler that configure could find.
You need to tell configure the path to the "real" C compiler
via the --with-CC option. On Solaris, the path is probably
something like "/opt/SUNWspro/SC4.0/bin/cc". If you have gcc
that will also work.
Q) When I run configure, it dies with the following error:
Fatal Error: config.cache exists from another platform!
Please remove it and re-run configure.
A) configure caches the results of its tests in a file called
config.cache to make re-running configure speedy. However,
if you are building sudo for a different platform the results
in config.cache will be wrong so you need to remove config.cache.
You can do this by "rm config.cache" or "make realclean".
Note that "make realclean" will also remove any object files
and configure temp files that are laying around as well.
Q) I built sudo on a Solaris >= 2.6 machine but the resulting binary
doesn't work on Solaris <= 2.5.1. Why?
A) Starting with Solaris 2.6, snprintf(3) is included in the standard
C library. To build a version of sudo on a >= 2.6 machine that
will run on a <= 2.5.1 machine, edit config.h and comment out the lines:
#define HAVE_SNPRINTF 1
#define HAVE_VSNPRINTF 1
and run make.
Q) I built sudo on a Solaris 11 (or higher) machine but the resulting
binary doesn't work older Solaris versions. Why?
A) Starting with Solaris 11, asprintf(3) is included in the standard
C library. To build a version of sudo on a Solaris 11 machine that
will run on an older Solaris release, edit config.h and comment out
the lines:
#define HAVE_ASPRINTF 1
#define HAVE_VASPRINTF 1
and run make.
Q) When I run "visudo" it says "sudoers file busy, try again later."
and doesn't do anything.
A) Someone else is currently editing the sudoers file with visudo.
Q) When I try to use "cd" with sudo it says "cd: command not found".
A) "cd" is a shell built-in command, you can't run it as a command
since a child process (sudo) cannot affect the current working
directory of the parent (your shell).
Q) When I try to use "cd" with sudo the command completes without
errors but nothing happens.
A) Even though "cd" is a shell built-in command, some operating systems
include a /usr/bin/cd command for some reason. A standalone
"cd" command is totally useless since a child process (cd) cannot
affect the current working directory of the parent (your shell).
Thus, "sudo cd /foo" will start a child process, change the
directory and immediately exit without doing anything useful.
Q) When I run sudo it says I am not allowed to run the command as root
but I don't want to run it as root, I want to run it as another user.
My sudoers file entry looks like:
bob ALL=(oracle) ALL
A) The default user sudo tries to run things as is always root, even if
the invoking user can only run commands as a single, specific user.
This may change in the future but at the present time you have to
work around this using the 'runas_default' option in sudoers.
For example:
Defaults:bob runas_default=oracle
would achieve the desired result for the preceding sudoers fragment.
Q) When I try to run sudo via ssh, I get the error:
sudo: no tty present and no askpass program specified
A) ssh does not allocate a tty by default when running a remote command.
Without a tty, sudo cannot disable echo when prompting for a password.
You can use ssh's "-t" option to force it to allocate a tty.
Alternately, if you do not mind your password being echoed to the
screen, you can use the "visiblepw" sudoers option to allow this.
Q) When I try to use SSL-enabled LDAP with sudo I get an error:
unable to initialize SSL cert and key db: security library: bad database.
you must set TLS_CERT in /etc/ldap.conf to use SSL
A) On systems that use a Mozilla-derived LDAP SDK there must be a
certificate database in place to use SSL-encrypted LDAP connections.
This file is usually /var/ldap/cert8.db or /etc/ldap/cert8.db.
The actual number after "cert" will vary, depending on the version
of the LDAP SDK that is being used. If you do not have a certificate
database you can either copy one from a mozilla-derived browser, such
as firefox, or create one using the "certutil" command. You can run
"certutil" as follows and press the <return> (or <enter>) key at the
password prompt:
# certutil -N -d /var/ldap
Enter a password which will be used to encrypt your keys.
The password should be at least 8 characters long,
and should contain at least one non-alphabetic character.
Enter new password: <return>
Re-enter password: <return>
Q) On HP-UX, when I run command via sudo it displays information
about the last successful login and last authentication failure
for every command. How can I fix this?
A) This output comes from /usr/lib/security/libpam_hpsec.so.1.
To suppress it, add a line like the following to /etc/pam.conf:
sudo session required libpam_hpsec.so.1 bypass_umask bypass_last_login
Q) On HP-UX, the umask setting in sudoers has no effect.
A) If your /etc/pam.conf file has the libpam_hpsec.so.1 session module
enabled, you may need to a add line like the following to pam.conf:
sudo session required libpam_hpsec.so.1 bypass_umask
Q) When I run sudo on AIX I get the following error:
setuidx(ID_EFFECTIVE|ID_REAL|ID_SAVED, ROOT_UID): Operation not permitted.
A) AIX's Enhanced RBAC is preventing sudo from running. To fix
this, add the following entry to /etc/security/privcmds (adjust
the path to sudo as needed) and run the setkst command as root:
/usr/local/bin/sudo:
accessauths = ALLOW_ALL
innateprivs = PV_DAC_GID,PV_DAC_O,PV_DAC_R,PV_DAC_UID,PV_DAC_W,PV_DAC_X,PV_FS_CHOWN,PV_PROC_ENV,PV_PROC_PRIO,PV_PROC_RAC
secflags = FSF_EPS
Q) Sudo configures and builds without error but when I run it I get
a Segmentation fault.
A) If you are on a Linux system, the first thing to try is to run
configure with the --disable-pie option, then "make clean" and
"make". If that fixes the problem then your operating system
does not properly support position independent executables.
Please send a message to [email protected] with system details such
as the Linux distro, kernel version and CPU architecture.
Q) When I run configure I get the following error:
dlopen present but libtool doesn't appear to support your platform.
A) Libtool doesn't know how to support dynamic linking on the operating
system you are building for. If you are cross-compiling, you need to
specify the operating system, not just the CPU type. For example:
--host powerpc-unknown-linux
instead of just:
--host powerpc
Q) How do you pronounce `sudo'?
A) The official pronunciation is soo-doo (for su "do"). However, an
alternate pronunciation, a homophone of "pseudo", is also common.