Spam Botnet on my LAN - How can I use the Sonicwall to identify the culprit?
I have a Sonicwall TZ100 configured as a network edge device, and I was just blacklisted because my Firewall IP is shown sending SPAM messages. I have setup a rule blocking all SMTP out with the copiers and Servers as exceptions and we have not been re-listed.
The infection persists on the network, however, and I am unable to track down where it is coming from.
How can I use the Sonicwall to see which host(s) are sending email now that the rule is blocking? I cannot figure out how to see this with the log settings, it's pretty awful.
Thanks!
The infection persists on the network, however, and I am unable to track down where it is coming from.
How can I use the Sonicwall to see which host(s) are sending email now that the rule is blocking? I cannot figure out how to see this with the log settings, it's pretty awful.
Thanks!
ASKER
What should I look at in the log to see the BLOCK rule? The new Sonicwall log is broken up into sections and it's not very friendly....to say the least!
ASKER
(ALSO Wireshark is not really an option since it's TCP, not a broadcast protocol, and we do not have a managed switch to port mirror the inside firewall interface. We just wouldn't get the SMTP traffic showing up).
If you filter wireshark using: tcp.port == 25 then it will show SMTP traffic on your network (I just tested on mine with no port mirroring)
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Good answer by DiverseIT ^^ sorry I dont have a tz100 available to me.
Glad I could help...thanks for the points!
Downloading wireshark network analyser and then filtering the protocol by SMTP may help locate the PC
Alternatively if the reporting on that device isnt great and you cant find it with wireshark then add an "allow" rule above the deny rule for a small selection of IP addresses on your network.
e.g. if you have 100 devices on your network then allow 1-25 and see if it still spams. Then 26-50 etc. That will narrow it down to one section.
Edit: On my Sonicwall (larger version), I go to Dashboard then Connection Monitor. I can filter by destination port (25 for SMTP) and it shows a list of hosts using that.