I write this knowing I still don’t know anything to speak of about syslog, but, sometimes you gotta act without knowing. I needed to send syslog to somewhere in a big hurry so I figured out the absolute minimum I needed to do to get it running on one of my other systems.
This all started because of a deficiency in the F5 ASM. At best it’s do slow when looking through the error log. But in particular there was one error that always timed out when I tried to bring up the details, a severity 5 error, so it looked pretty important. Worse, local logging, even though it is selected, also does not work – the /var/log/asm file exists but contains basically nothing of interest. I suppose there is some super-fancy and complicated MySQL command you could run to view the logs, but that would take a long time to figure out.
So for me the simplest route was to enable remote syslog on a Linux server and send the ASM logging to it. This seems to be working, by the way.
The minimal steps
Again, this was for Suse Enterprise Linux running syslog-ng.
- modify /etc/sysconfig/syslog as per the next step
- modify /etc/syslog-ng/syslog-ng.conf as per the next step
- uncomment this line: udp(ip(“0.0.0.0”) port(514));
- launch yast (I use curses-based yast [no X-Windows] which is really cantankerous)
- go to Security and Users -> Firewall -> Allowed services -> Internal Zone -> Advanced
- add udp port 514 as additional allowed Ports in internal zone and save it
- service syslog stop
- service syslog start
- You should start seeing entries in /var/log/localmessages as in this suitably anonymized example (I added a couple line breaks for clarity:
Jul 27 14:42:22 f5-drj-mgmt ASM:"7653503868885627313","18.104.22.168","/Common/drjohnstechtalk.com_profile","blocked","/drjcrm/bi/tjhmore345","0","Illegal URL,Attack signature detected","200021075","Automated client access ""curl""","US","<?xml version='1.0' encoding='UTF-8'?><BAD_MSG><violation_masks><block>44e7f1ffebff2dfb-8000000000000000</block><alarm>44f7f1ffebff2dfb-8000000000000000</alarm><learn>44e7f1ffe3ff2dfb-8000000000000000</learn><staging>0000000000000000-0000000000000000</staging></violation_masks><request-violations><violation><viol_index>42</viol_index><viol_name>VIOL_ATTACK_SIGNATURE</viol_name><context>request</context><sig_data><sig_id>200021075</sig_id> <blocking_mask>7</blocking_mask><kw_data><buffer>VXNlci1BZ2VudDogY3VybC83LjE5LjcgKHg4Nl82NC1yZWRoYXQtbGludXgtZ251KSBsaWJjdXJsLzcuMTkuNyBOU1MvMy4yNy4xIHpsaWIvMS4yLjMgbGliaWRuLzEuMTggbGlic3NoMi8xLjQuMg0KSG9zdDogYWctaW50ZWw=</buffer> <offset>0</offset><length>16</length></kw_data></sig_data></violation><violation><viol_index>38</viol_index> <viol_name>VIOL_URL</viol_name></violation></request-violations></BAD_MSG>","GET /drjcrm/bi/tjhmore345 HTTP/1.1\r\nUser-Agent: curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.27.1 zlib/1.2.3 libidn/1.18 libssh2/1.4.2\r\nHost: drjohnstechtalk.com\r\nAccept: */*\r\n\r\n"
Interestingly, there is no syslogd on this particular system, and yet the “-r” flag is designed for syslogd – it’s what turns it into a remote syslogging daemon. And yet it works.
It’s easy enough to log these messages to their own file, I just don’t know how to do it yet because I don’t need to. I learn as I need to. just as I learned enough to publish this tip.
We have demonstrated activating the simplest possible remote syslogger on Suse Linux Enterprise Server.