Which software to use for bot detection over Lan

[Gertjan]

@OpenWifi said in Which software to use for bot detection over Lan:

I believe this means clients on the lan would not be able to send mail!!

Again, you admin a firewall. There is no such thing as "Wondering" and "Believing". Things happens because you let them happen. And things that you do not want, you stop. You are the boss.
A boss doesn't "trust" or "believe".

Maybe this is new to you :
Mail clients like Outlook Express, Outlook (Office) or Thunderbird should not use port 25 to send mail.
They are set up to use (as stated) above : port 587 or port 465. These two port permit some one to send mails, if they can authenticity themselves first == have an account at that mail server.

Like : you can not send mail using mail.gmail.com on port 25 : gmail does not allow this. gmail is not an open relay. You should use 587, no, better : port 465.

For historical reasons, ISP's allow that you use their mail servers so you can send your (not your unkown visitors !!) send mail to some one. This is an exception. Do understand that the ISP knows who you are : you are using their "land line" to connect to their services.