Sudo Log Server Configuration Manual

SUDO_LOGSRVD.CONF(5)

sudo_logsrvd.confconfiguration for sudo_logsrvd

The sudo_logsrvd.conf file is used to configure the sudo_logsrvd log server. It uses an INI-style format made up of sections in square brackets and “key = value” pairs specific to each section below the section name. Depending on the key, values may be integers, booleans or strings. Section and key names are not case sensitive, but values are.

The pound sign (‘#’) is used to indicate a comment. Both the comment character and any text after it, up to the end of the line, are ignored. Lines beginning with a semi-colon (‘;’) are also ignored.

Long lines can be continued with a backslash (‘\’) as the last character on the line. Note that leading white space is removed from the beginning of lines even when the continuation character is used.

The EXAMPLES section contains a copy of the default sudo_logsrvd.conf file.

The following configuration sections are recognized:

  • server
  • iolog
  • eventlog
  • syslog
  • logfile

Each section is described in detail below.

The server section configures the address and port the server will listen on. The following keys are recognized:

listen_address = host[:port]
The host name or IP address and optional port to listen on. If no port is specified, port 30344 will be used. The host may be a host name, an IPv4 address, an IPv6 address in square brackets or the wild card entry ‘*’. A host setting of ‘*’ will cause sudo_logsrvd to listen on all configured network interfaces.

If a port is specified, it may either be a port number or a known service name as defined by the system service name database. The default value is listen_address = *:30344 which will listen on all configured network interfaces. Multiple listen_address lines may be specified to listen on more than one interface.

pid_file = path
The path to the file containing the process ID of the running sudo_logsrvd. This file is not created when sudo_logsrvd is run with the -n option. The default value is /var/run/sudo/sudo_logsrvd.pid.
tcp_keepalive = boolean
If true, sudo_logsrvd will enable the TCP keepalive socket option on the client connection. This enables the periodic transmission of keepalive messages to the client. If the client does not respond to a message, the connection will be closed.
timeout = number
The amount of time, in seconds, sudo_logsrvd will wait for the client to respond. A value of 0 will disable the timeout. The default value is 30.
tls = boolean
If true, sudo_logsrvd will secure network connections with Transport Layer Security (TLS) version 1.2 or 1.3. Versions of TLS prior to 1.2 are not supported. The tls_cert and tls_key settings are also required when TLS is enabled. The default value is false.
tls_cacert = path
The path to a certificate authority bundle file, in PEM format, to use instead of the system's default certificate authority database when authenticating clients. The default is to use the system's default certificate authority database.
tls_cert = path
The path to the server's certificate file, in PEM format. This setting is required when TLS is enabled.
tls_checkpeer = bool
If true, client certificates will be validated by the server; clients without a valid certificate will be unable to connect. If false, no validation of client certificates will be performed. It true and client certificates are created using a private certificate authority, the tls_cacert setting must be set to a CA bundle that contains the CA certificate used to generate the client certificate. The default value is false.
tls_ciphers_v12 = string
A list of ciphers to use for connections secured by TLS version 1.2 only, separated by a colon ‘:’. See the CIPHER LIST FORMAT section in openssl-ciphers(1) for full details. The default value is HIGH:!aNULL which consists of encryption cipher suites with key lengths larger than 128 bits, and some cipher suites with 128-bit keys. Cipher suites that offer no authentication are excluded.
tls_ciphers_v13 = string
A list of ciphers to use for connections secured by TLS version 1.3 only, separated by a colon ‘:’. Supported cipher suites depend on the version of OpenSSL used, but should include the following:

TLS_AES_128_GCM_SHA256
 
TLS_AES_256_GCM_SHA384
 
TLS_CHACHA20_POLY1305_SHA256
 
TLS_AES_128_CCM_SHA256
 
TLS_AES_128_CCM_8_SHA256
 

The default cipher suite is TLS_AES_256_GCM_SHA384.

tls_dhparams = path
The path to a file containing custom Diffie-Hellman parameters in PEM format. This file can be created with the following command:
openssl dhparam -out /etc/sudo_logsrvd_dhparams.pem 2048
    

By default, sudo_logsrvd will use the OpenSSL defaults for Diffie-Hellman key generation.

tls_key = path
The path to the server's private key file, in PEM format. This setting is required when TLS is enabled.
tls_verify = bool
If true, the server certificate will be verified at startup and clients will authenticate the server by verifying its certificate and identity. If false, no verification is performed of the server certificate by the server or the client. When using self-signed certificates without a certificate authority, this setting should be set to false. The default value is true.

The iolog section configures I/O log parameters. These settings are identical to the I/O configuration in sudoers(5). The following keys are recognized:

iolog_compress = boolean
If set, I/O logs will be compressed using zlib. Enabling compression can make it harder to view the logs in real-time as the program is executing due to buffering. The default value is false.
iolog_dir = path
The top-level directory to use when constructing the path name for the I/O log directory. The session sequence number, if any, is stored in the directory. The default value is /var/log/sudo-io.

The following percent (‘%’) escape sequences are supported:

expanded to a monotonically increasing base-36 sequence number, such as 0100A5, where every two digits are used to form a new directory, e.g., 01/00/A5
expanded to the invoking user's login name
expanded to the name of the invoking user's real group-ID
expanded to the login name of the user the command will be run as (e.g., root)
expanded to the group name of the user the command will be run as (e.g., wheel)
expanded to the local host name without the domain name
expanded to the base name of the command being run

In addition, any escape sequences supported by the system's strftime(3) function will be expanded.

To include a literal ‘%’ character, the string ‘%%’ should be used.

iolog_file = path
The path name, relative to iolog_dir, in which to store I/O logs. Note that iolog_file may contain directory components. The default value is %{seq}.

See the iolog_dir setting above for a list of supported percent (‘%’) escape sequences.

In addition to the escape sequences, path names that end in six or more Xs will have the Xs replaced with a unique combination of digits and letters, similar to the mktemp(3) function.

If the path created by concatenating iolog_dir and iolog_file already exists, the existing I/O log file will be truncated and overwritten unless iolog_file ends in six or more Xs.

iolog_flush = boolean
If set, I/O log data is flushed to disk after each write instead of buffering it. This makes it possible to view the logs in real-time as the program is executing but may significantly reduce the effectiveness of I/O log compression. The default value is true.
iolog_group = name
The group name to look up when setting the group-ID on new I/O log files and directories. If iolog_group is not set, the primary group-ID of the user specified by iolog_user is used. If neither iolog_group nor iolog_user are set, I/O log files and directories are created with group-ID 0.
iolog_mode = mode
The file mode to use when creating I/O log files. Mode bits for read and write permissions for owner, group or other are honored, everything else is ignored. The file permissions will always include the owner read and write bits, even if they are not present in the specified mode. When creating I/O log directories, search (execute) bits are added to match the read and write bits specified by iolog_mode. The default value is 0600.
iolog_user = name
The user name to look up when setting the owner of new I/O log files and directories. If iolog_group is set, it will be used instead of the user's primary group-ID. By default, I/O log files and directories are created with user and group-ID 0.
maxseq = number
The maximum sequence number that will be substituted for the “%{seq}” escape in the I/O log file (see the iolog_dir description above for more information). While the value substituted for “%{seq}” is in base 36, maxseq itself should be expressed in decimal. Values larger than 2176782336 (which corresponds to the base 36 sequence number “ZZZZZZ”) will be silently truncated to 2176782336. The default value is 2176782336.

The eventlog section configures how (and if) security policy events are logged.

log_type = string
Where to log accept, reject and alert events reported by the policy. Supported values are syslog, logfile, and none. The default value is syslog.
log_format = string
The event log format. Supported log formats are “sudo” for traditional sudo-style logs and “json” for JSON-format logs. The JSON log entries contain the full contents of the accept, reject and alert messages. The default value is sudo.

The syslog section configures how events are logged via syslog(3).

facility = string
Syslog facility if syslog is being used for logging. Defaults to auth.

The following syslog facilities are supported: authpriv (if your OS supports it), auth, daemon, user, local0, local1, local2, local3, local4, local5, local6, and local7.

accept_priority = string
Syslog priority to use when the user is allowed to run a command and authentication is successful. Defaults to notice.

The following syslog priorities are supported: alert, crit, debug, emerg, err, info, notice, warning, and none. Setting it to a value of none will disable logging of successful commands.

reject_priority = string
Syslog priority to use when the user is not allowed to run a command or when authentication is unsuccessful. Defaults to alert.

See accept_priority for the list of supported syslog priorities.

alert_priority = string
Syslog priority to use for event log alert messages received from the client. Defaults to alert.

See accept_priority for the list of supported syslog priorities.

maxlen = number
On many systems, syslog(3) has a relatively small log buffer. IETF RFC 5424 states that syslog servers must support messages of at least 480 bytes and should support messages up to 2048 bytes. By default, sudo_logsrvd creates log messages up to 960 bytes which corresponds to the historic BSD syslog implementation which used a 1024 byte buffer to store the message, date, hostname and program name.

To prevent syslog messages from being truncated, sudo_logsrvd will split up sudo-style log messages that are larger than maxlen bytes. When a message is split, additional parts will include the string “(command continued)” after the user name and before the continued command line arguments. JSON-format log entries are never split and are not affected by maxlen.

The logfile section consists of settings related to logging to a plain file (not syslog).

path = string
The path to the file-based event log. This path must be fully-qualified and start with a ‘/’ character. The default value is /var/log/sudo.log.
time_format = string
The string used when formatting the date and time for file-based event logs. Formatting is performed via the system's strftime(3) function so any escape sequences supported by that function will be expanded. The default value is “%h %e %T” which produces dates like “Oct 3 07:15:24” in the C locale.

/etc/sudo_logsrvd.conf
Sudo log server configuration file

#
# sudo logsrv configuration
#

[server]
# The host name or IP address and port to listen on.  If no port is
# specified, port 30344 will be used.
# The following forms are accepted:
#   listen_address = hostname
#   listen_address = hostname:port
#   listen_address = IPv4_address
#   listen_address = IPv4_address:port
#   listen_address = [IPv6_address]
#   listen_address = [IPv6_address]:port
#
# Multiple listen_address settings may be specified.
# The default is to listen on all addresses.
#listen_address = *:30344

# The file containing the ID of the running sudo_logsrvd process.
#pid_file = /var/run/sudo/sudo_logsrvd.pid

# If set, enable the SO_KEEPALIVE socket option on the connected socket.
#tcp_keepalive = true

# The amount of time, in seconds, the server will wait for the client to
# respond.  A value of 0 will disable the timeout.  The default value is 30.
#timeout = 30

# If set, secure connections with TLS 1.2 or 1.3.
# By default, server connections are not encrypted.
#tls = true

# If set, server certificate will be verified at server startup and
# also connecting clients will perform server authentication by
# verifying the server's certificate and identity.
#tls_verify = true

# Whether to verify client certificates for TLS connections.
# By default client certs are not checked.
#tls_checkpeer = false

# Path to the certificate authority bundle file in PEM format.
# Required if 'tls_verify' or 'tls_checkpeer' is set.
#tls_cacert = /etc/ssl/sudo/cacert.pem

# Path to the server's certificate file in PEM format.
# Required for TLS connections.
#tls_cert = /etc/ssl/sudo/certs/logsrvd_cert.pem

# Path to the server's private key file in PEM format.
# Required for TLS connections.
#tls_key = /etc/ssl/sudo/private/logsrvd_key.pem

# TLS cipher list (see "CIPHER LIST FORMAT" in the openssl-ciphers manual).
# NOTE that this setting is only effective if the negotiated protocol
# is TLS version 1.2.
# The default cipher list is HIGH:!aNULL.
#tls_ciphers_v12 = HIGH:!aNULL

# TLS cipher list if the negotiated protocol is TLS version 1.3.
# The default cipher list is TLS_AES_256_GCM_SHA384.
#tls_ciphers_v13 = TLS_AES_256_GCM_SHA384

# Path to the Diffie-Hellman parameter file in PEM format.
# If not set, the server will use the OpenSSL defaults.
#tls_dhparams = /etc/ssl/sudo/logsrvd_dhparams.pem

[iolog]
# The top-level directory to use when constructing the path name for the
# I/O log directory.  The session sequence number, if any, is stored here.
#iolog_dir = /var/log/sudo-io

# The path name, relative to iolog_dir, in which to store I/O logs.
# Note that iolog_file may contain directory components.
#iolog_file = %{seq}

# If set, I/O logs will be compressed using zlib.  Enabling compression can
# make it harder to view the logs in real-time as the program is executing.
#iolog_compress = false

# If set, I/O log data is flushed to disk after each write instead of
# buffering it.  This makes it possible to view the logs in real-time
# as the program is executing but reduces the effectiveness of compression.
#iolog_flush = true

# The group to use when creating new I/O log files and directories.
# If iolog_group is not set, the primary group-ID of the user specified
# by iolog_user is used.  If neither iolog_group nor iolog_user
# are set, I/O log files and directories are created with group-ID 0.
#iolog_group = wheel

# The user to use when setting the user-ID and group-ID of new I/O
# log files and directories.  If iolog_group is set, it will be used
# instead of the user's primary group-ID.  By default, I/O log files
# and directories are created with user and group-ID 0.
#iolog_user = root

# The file mode to use when creating I/O log files.  The file permissions
# will always include the owner read and write bits, even if they are
# not present in the specified mode.  When creating I/O log directories,
# search (execute) bits are added to match the read and write bits
# specified by iolog_mode.
#iolog_mode = 0600

# The maximum sequence number that will be substituted for the "%{seq}"
# escape in the I/O log file.  While the value substituted for "%{seq}"
# is in base 36, maxseq itself should be expressed in decimal.  Values
# larger than 2176782336 (which corresponds to the base 36 sequence
# number "ZZZZZZ") will be silently truncated to 2176782336.
#maxseq = 2176782336

[eventlog]
# Where to log accept, reject and alert events.
# Accepted values are syslog, logfile, or none.
# Defaults to syslog
#log_type = syslog

# Event log format.
# Currently only sudo-style event logs are supported.
#log_format = sudo

[syslog]
# The maximum length of a syslog payload.
# On many systems, syslog(3) has a relatively small log buffer.
# IETF RFC 5424 states that syslog servers must support messages
# of at least 480 bytes and should support messages up to 2048 bytes.
# Messages larger than this value will be split into multiple messages.
#maxlen = 960

# The syslog facility to use for event log messages.
# The following syslog facilities are supported: authpriv (if your OS
# supports it), auth, daemon, user, local0, local1, local2, local3,
# local4, local5, local6, and local7.
#facility = authpriv

# Syslog priority to use for event log accept messages, when the command
# is allowed by the security policy.  The following syslog priorities are
# supported: alert, crit, debug, emerg, err, info, notice, warning, none.
#accept_priority = notice

# Syslog priority to use for event log reject messages, when the command
# is not allowed by the security policy.
#reject_priority = alert

# Syslog priority to use for event log alert messages reported by the
# client.
#alert_priority = alert

[logfile]
# The path to the file-based event log.
# This path must be fully-qualified and start with a '/' character.
#path = /var/log/sudo

# The format string used when formatting the date and time for
# file-based event logs.  Formatting is performed via strftime(3) so
# any format string supported by that function is allowed.
#time_format = %h %e %T

strftime(3), sudo.conf(5), sudoers(5), sudo(8), sudo_logsrvd(8)

See the HISTORY file in the sudo distribution (https://www.sudo.ws/history.html) for a brief history of sudo.

Many people have worked on sudo over the years; this version consists of code written primarily by:

Todd C. Miller

See the CONTRIBUTORS file in the sudo distribution (https://www.sudo.ws/contributors.html) for an exhaustive list of people who have contributed to sudo.

If you feel you have found a bug in sudo, please submit a bug report at https://bugzilla.sudo.ws/

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

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 https://www.sudo.ws/license.html for complete details.