Splunk Search

How do I Search for IP address hitting a specific port + any other ports?

lucamarc
Path Finder

I think this should be within my grasp, but I don't seem to be able to create a search that returns what I'm looking for.

I'm trying to return from syslog any IP address that hits a specific port (say 12345), but also attempts connecting to any other ports other than 12345. In my scenario, a well-behaved host should exclusively connect to port 12345 and nothing else.

What I'm coming up with either returns no results or only results matching DPT=12345; it does not return anything in between.

Thanks

0 Karma

horsefez
Motivator

Hi @lucamarc,

how about something along those lines.
As you didn't provide any example log data, I'm not sure how your logs look like. --> This is pseudo-code.

index=whatever DPT=* | eval port_type=if(DPT=="12345", "Normal", "Other") | stats values(DPT) by IP, port_type

0 Karma

lucamarc
Path Finder

Thanks @pyro_wood, I probably didn't explain this very well. I think that what you suggested is returning every host that ever attempted a connection, no matter if it never attempted connecting to port 12345.

I'm only interested in (the very few) IPs that both:
1. connect (or attempt to connect) to port 12345 AND
2. attempted connecting to a different port (any other port)

I'm collecting logs from Ubuntu 18.04 LST servers. This is the query I tried, based on your suggestion:

index="syslog" DPT=* | eval port_type=if(DPT=="12345", "Normal", "Abuser") | stats values(DPT) by SRC, port_type
0 Karma
Get Updates on the Splunk Community!

.conf24 | Day 0

Hello Splunk Community! My name is Chris, and I'm based in Canberra, Australia's capital, and I travelled for ...

Enhance Security Visibility with Splunk Enterprise Security 7.1 through Threat ...

(view in My Videos)Struggling with alert fatigue, lack of context, and prioritization around security ...

Troubleshooting the OpenTelemetry Collector

  In this tech talk, you’ll learn how to troubleshoot the OpenTelemetry collector - from checking the ...