TROUBLESHOOTING.md

Troubleshooting tips and FAQ for Sudo

When I run configure, it says "C compiler cannot create executables".

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.

When I run configure, it says "sudo requires the 'ar' utility to build".

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.

Sudo compiles and installs successfully but when I try to run it I get:

The "no new privileges" flag is set, which prevents sudo from
running as root.  If sudo is running in a container, you may
need to adjust the container configuration to disable the flag.

Sudo was run by a process that has the Linux "no new privileges" flag set. This causes the set-user-ID bit to be ignored when running an executable, which will prevent sudo from functioning. The most likely cause for this is running sudo within a container that sets this flag. Check the documentation to see if it is possible to configure the container such that the flag is not set.

Sudo compiles and installs successfully 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

Sudo must be set-user-ID root to do its work. Either /usr/local/bin/sudo is not owned by user-ID 0 or the set-user-ID 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 4755 /usr/local/bin/sudo

Sudo compiles and installs successfully 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?

The owner and permissions on the sudo binary appear to be OK but when sudo ran, the set-user-ID 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 set-user-ID binaries. The output of the 'mount' command should tell you if the file system is mounted with the 'nosuid' option. The other possible cause 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 user-ID 0 mapped to a non-privileged ID (usually -2). You should be able to determine whether sudo is located on an NFS-mounted filesystem by running "df `which sudo`".

Sudo never gives me a chance to enter a password using PAM

It just says "Sorry, try again." three times and exits.

You didn't setup PAM to work with sudo. On RedHat or Fedora Linux this generally means installing the sample pam.conf file as /etc/pam.d/sudo. See the example pam.conf file for hints on what to use for other Linux systems.

Sudo says my account has expired but I know it has not

If you get the following error from sudo:

Account expired or PAM config lacks an 'account' section for sudo,
contact your system administrator`

double-check the /etc/shadow file to verify that the target user (for example, root) does not have the password expiration field set. A common way to disable access to an account is to set the expiration date to 1, such as via usermod -e 1. If the account is marked as expired, sudo will not allow you to access it.

If, however, the account has not expired, it is possible that the PAM configuration lacks an 'account' specification. On Linux this usually means you are missing a line in /etc/pam.d/sudo similar to:

account    required    pam_unix.so

Sudo is configured use syslog but nothing gets logged

Make sure you have an entry in your syslog.conf file to save the sudo messages (see the example 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 (e.g., touch /var/log/sudo).

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.

Sudo won't accept my password, even when entered correctly

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). There is no define needed for 4.4BSD-based shadow passwords which just use the standard getpw* routines.

Can sudo use the ssh agent instead of asking for the user's password?

Not directly, but you can use a PAM module like pam_ssh_agent_auth or pam_ssh for this purpose.

I want to place the sudoers file in a directory other than /etc

Use the --sysconfdir option to configure. For example:

configure --sysconfdir=/dir/you/want/sudoers/in

Alternately, you can set the path in the sudo.conf file as an argument to the sudoers.so plugin. For example:

Plugin sudoers_policy sudoers.so sudoers_file=/path/to/sudoers

Can I put the sudoers file in NIS/NIS+?

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 README.LDAP.md and the sudoers.ldap manual.

I don't run sendmail, can I still use sudo?

Yes, you just need to disable mailing with a line like:

Defaults !mailerpath

in your sudoers file or run configure with the --without-sendmail option.

How can I make visudo use a different editor?

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.

Why does sudo modify the command's environment?

By default, sudo runs commands with a new, minimal environment. The 'env_keep' setting in sudoers can be used to control which environment variables are preserved from the invoking user's environment via the 'env_keep' setting in sudoers.

While it is possible to disable the 'env_reset' setting, which will preserve all environment variables that don't match a black list, doing so is strongly discouraged. See the "Command environment" section of the sudoers manual for more information.

Why does sudo reset the HOME environment variable?

Many programs use the HOME environment variable to locate configuration and data files. Often, these configuration files are treated as trusted input that affects how the program operates. By controlling the configuration files, a user may be able to cause the program to execute other commands without sudo's restrictions or logging.

Some programs perform extra checks when the real and effective user-IDs differ, but because sudo runs commands with all user-IDs set to the target user, these checks are insufficient.

While it is possible to preserve the value of the HOME environment variable by adding it to the 'env_keep' list in the sudoers file, doing so is strongly discouraged. Users wishing to edit files with sudo should run sudoedit (or sudo -e) to get their accustomed editor configuration instead of invoking the editor directly.

How can I prevent sudo from asking for a password?

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 examples/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.

The configure scripts says no acceptable cc found in $PATH

/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.

The configure scripts says "config.cache exists from another platform!"

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 the config.cache file. You can do this via rm config.cache, or make realclean to also remove any object files and configure temp files that are present.

When I run 'visudo' it says "sudoers file busy, try again later."

Someone else is currently editing the sudoers file with visudo.

When I try to use 'cd' with sudo it says "cd: command not found"

'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).

When I try to use 'cd' with sudo nothing happens.

Even though 'cd' is a shell built-in command, some operating systems include a /usr/bin/cd command for completeness. 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.

How can I run a command via sudo as a user other than root?

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, given the following sudoers rule:

bob ALL=(oracle) ALL

You can cause sudo to run all commands as 'oracle' for user 'bob' with a sudoers entry like:

Defaults:bob runas_default=oracle

When I try to run sudo via ssh, I get an error:

sudo: a terminal is required to read the password; either use the -S
      option to read from standard input or configure an askpass helper

If sudo needs to authenticate a user, it requires access to the user's terminal to disable echo so the password is not displayed to the screen. The above message indicates that no terminal was present.

When running a command via ssh, a terminal is not allocated by default which can cause this message. The '-t' option to ssh will force it to allocate a tty. Alternately, you may be able to use the ssh-askpass utility to prompt for the password if X11 forwarding is enabled and an askpass helper is configured in the sudo.conf file. If you do not mind your password being echoed to the screen, you may use sudo's -S option to read the password from the standard input. Alternately, you may set the 'visiblepw' sudoers option which will allow the password to be entered even when echo cannot be disabled, though this is not recommended.

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

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 (or ) 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>

After upgrading my system, sudo_logsrvd gives the error:

X509_verify_cert: CA cert does not include key usage extension

This can happen if you are using self-signed certificates that do not include the key usage extension. This error can occur if the certificates were generated using OpenSSL 1.x but sudo_logsrvd now uses OpenSSL 3.x, for example after a system upgrade. The x509 certificate validation in OpenSSL 3.x now requires that the key usage extension be present. One way to address this is to disable certificate verification in sudo_logsrvd by setting the tls_verify key in the [server] section to false. Alternately, you can simply remove your old CA and the associated certificates and create a new one using an updated /etc/ssl/openssl.cnf file. See the sudo_logsrvd manual for more information on creating self-signed certificates.

On HP-UX, the umask setting in sudoers has no effect.

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

When I run sudo -i shell_alias I get "command not found"

Commands run via sudo -i are executed by the shell in non-interactive mode. The bash shell will only parse aliases in interactive mode unless the 'expand_aliases' shell option is set. If you add shopt -s expand_aliases to your .bash_profile (or .profile if using that instead) the aliases should now be available to sudo -i.

When I run sudo on AIX I get the following error:

setuidx(ID_EFFECTIVE|ID_REAL|ID_SAVED, ROOT_UID): Operation not permitted.

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_R,PV_DAC_UID,PV_DAC_X,PV_FS_CHOWN,PV_PROC_PRIO,PV_NET_PORT,PV_NET_CNTL,PV_SU_UID
    secflags = FSF_EPS

Sudo builds without error but when I run it I get a Segmentation fault.

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. Send a message to [email protected] with system details such as the Linux distro, kernel version, and CPU architecture.

When I run configure I get the following error:

dlopen present but libtool doesn't appear to support your platform.

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

How do you pronounce 'sudo'?

The official pronunciation is soo-doo (for su 'do'). However, an alternate pronunciation, a homophone of 'pseudo', is also common.