Live visualizing Mikrotik firewall traffic with Logstalgia

Posted at 9:54 pm in Uncategorized

Previously I’ve written about visualizing firewall activity. Revitalizing a fireplot graphing tool gives a nice day-to-day overview, but after being reminded of Logstalgia in this Imgur post I wanted to give live visualization a shot.

Logstalgia is a neat tool for visualizing activity, by feeding it log files or live feeds. It’s originally designed for parsing web server logs, but it also accepts a generic format that allows for other purposes as well. By writing a short Perl script that acts like a syslog server (receiver) and converting the input to a format that Logstalgia accepts, my Mikrotik router is now live reporting any connection attempt to or through the firewall. For the visualization below I triggered a portscan to create some activity, or the video would be rather boring.

To make this work, the firewall must somehow identify traffic that’s being denied (unless you only log blocked traffic). The script will then pass only these log records to Logstalgia. I’ve been testing this with a Mikrotik device, but any firewall able to log to or through syslog will work fine.

Original syslog input

Feb 6 21:42:36 BLOCK: in:ether1 out:(none), src-mac 00:00:00:6a:f3:9c,
proto ICMP (type 8, code 0),>, len 28


Logstalgia formatted output:



I’m starting the perl script and Logstalgia like this:

./syslog2logstalgia | logstalgia -800x640 --disable-progress -x \
--no-bounce --hide-response-code --sync \
-g "TCP,URI=TCP,45" -g "UDP,URI=UDP,45" -g "ICMP,URI=ICMP,10" \


Note that visualizing firewall logs with Logstalgia has been done by a lot of other people. Howtos for other firewall products may be available via your favourite search engine.

Written by bjorn on February 6th, 2016

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