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Mike Pennington
Asked: 2012-06-20 12:20:01 +0800 CST

syslog ip ranges to specific files using `rsyslog`

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I have many Cisco / JunOS routers and switches that send logs to my Debian server, which uses rsyslogd.

How can I configure rsyslogd to send these router / switch logs to a specific file, based on their source IP address? I do not want to pollute general system logs with these entries.

For instance:

  • all routers in Chicago (source ip block: 172.17.25.0/24) to only log to /var/log/net/chicago.log.
  • all routers in Dallas (source ip block 172.17.27.0/24) to only log to /var/log/net/dallas.log.
  • Delete all APF-3-RCV_UNSUPP_MSG messages without logging them
  • Send logs for 172.17.4.4 to a file named /var/log/net/firewall.log
  • Forward firewall logs to 10.14.12.12 using UDP port 514

Finally, these logs should be rotated daily for up to 30 days and compressed.

NOTE: I am answering my own question

linux networking unix rsyslog

2 Answers

  1. Best Answer

    rsyslogd Configuration

    In /etc/rsyslogd.conf

    # provides remote UDP syslog reception
$ModLoad imudp
$UDPServerRun 514

# If logging to an NFS mount, use these settings...
#    "OMFileFlushOnTXEnd off" avoids fsync on every write...
#     mount -o hard,rsize=32768,wsize=32768,noacl,noatime,nodiratime -t nfs
$OMFileIOBufferSize 768k
$OMFileAsyncWriting on
$OMFileFlushOnTXEnd off
$OMFileFlushInterval 10
$MainMsgQueueSize 100000


# kill all INTF-FLAP messages...
if $msg contains 'INTF-FLAP' then /dev/null
&~
## Cisco ACS Accounting...
if ($fromhost-ip=='172.17.16.20') and ($programname == 'CSCOacs_TACACS_Accounting') then /var/log/tacacs_acct.log
&~
## CiscoACS 5.4 TACACS Authentication
if ($fromhost-ip=='172.17.16.20') and ($programname == 'CSCOacs_Passed_Authentications') then /var/log/tacacs_auth.log
&~

# Logging for Chicago issues...
if $fromhost-ip startswith '172.17.25' then /var/log/net/chicago.log
& ~
# Logging for Dallas issues...
if $fromhost-ip startswith '172.17.27' then /var/log/net/dallas.log
& ~
# Logging for firewall...
if $fromhost-ip=='172.17.4.4' then @10.14.12.12
if $fromhost-ip=='172.17.4.4' then /var/log/net/firewall.log
& ~

    Each of the &~ entries prevents fall-through to the rest of the rsyslog.conf configuration; thus I won't see router syslog entries in /var/log/messages.

    Touch all syslog files:

    • touch /var/log/net/chicago.log
    • touch /var/log/net/dallas.log
    • touch /var/log/net/firewall.log

    Restart rsyslogd with /etc/init.d/rsyslogd restart

    Log rotation

    In /etc/logrotate.d/rsyslog

    /var/log/net/*.log
{
        copytruncate
        rotate 30
        daily
        missingok
        dateext
        notifempty
        delaycompress
        create root 664 root root
        compress
        maxage 31
        sharedscripts
        lastaction
                # RHEL: Use "/sbin/service rsyslog restart"
                # Debian / Ubuntu: Use "invoke-rc.d rsyslog reload > /dev/null"
                invoke-rc.d rsyslog reload > /dev/null
        endscript
}
    • 14

  2. Also, I found this on the rsyslog wiki that could serve as future refernce for someone.

    http://www.rsyslog.com/storing-messages-from-a-remote-system-into-a-specific-file/

    • 4