CIS Ubuntu 14.04 LTS - 4.2.1.5 Ensure remote rsyslog messages are only accepted on designated log hosts

DevOps & Security

Configure rsyslog to accept remote messages only on designated log hosts

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4.2.1.5 Ensure remote rsyslog messages are only accepted on designated log hosts (Not Scored)

Profile Applicability

Level 1 - Server
Level 1 - Workstation

Description

By default, rsyslog does not listen for log messages coming in from remote systems. The ModLoad tells rsyslog to load the imtcp.so module so it can listen over a network via TCP. The InputTCPServerRun option instructs rsyslogd to listen on the specified TCP port.

Rationale

The guidance in the section ensures that remote log hosts are configured to only accept rsyslog data from hosts within the specified domain and that those systems that are not designed to be log hosts do not accept any remote rsyslog messages. This provides protection from spoofed log data and ensures that system administrators are reviewing reasonably complete syslog data in a central location.

Audit Procedure

Run the following commands and verify the resulting lines are uncommented on designated log hosts and commented or removed on all others:

grep '$ModLoad imtcp' /etc/rsyslog.conf /etc/rsyslog.d/*.conf
grep '$InputTCPServerRun' /etc/rsyslog.conf /etc/rsyslog.d/*.conf

Expected Result

On designated log hosts:

$ModLoad imtcp
$InputTCPServerRun 514

On non-log hosts, these lines should be commented out or absent.

Remediation

For hosts that are designated as log hosts, edit the /etc/rsyslog.conf file and un-comment or add the following lines:

$ModLoad imtcp
$InputTCPServerRun 514

For hosts that are not designated as log hosts, edit the /etc/rsyslog.conf file and comment or remove the following lines:

# $ModLoad imtcp
# $InputTCPServerRun 514

Run the following command to reload the rsyslogd configuration:

pkill -HUP rsyslogd

Notes: The $MoadLoad imtcp line can have the .so extension added to the end of the module, or use the full path to the module.

Default Value

rsyslog does not listen for remote messages by default.

References

See the rsyslog(8) man page for more information.

Profile

Level 1 - Server
Level 1 - Workstation