does anyone know much about Gnat Box?

[PalmStrike]

Hi, we have a small network here, 2 nt4 servers, and a bunch of 98 and 95 pc's, and we have a Gnat box fire wall which is like a box of it's own. I have been told that it is very good, and I am under the impression that it could be very flexible too,but know nothing of firewalls at the moment, I have just been going through the threads here to learn a bit while our email server defrags.

Plus, I am quite concerned that even if it is a fine firewall, I could bet that it is not confgured even slightly sensibly, are there specific ports that I should be aware of that act like a big old welcome mat?

 

[PcLinuxGuru]

I think you mean NAT (Network Address Translation) not gnat which could be almost any OS acting solely as a firewall/router....

Please let me know if I am wrong in my assumption

 

[SgtB]

Guru-
No GNAT is a vendor. They make hardware firewalls I think.

PalmStrike -
Little lesson on firewall configuration. You do not just block ports that are 'dangerous'. You block everything, then just open the ports your company needs. For generic internet access you'd open outbound ports 80(http),443(https),21(ftp), and maybe 53 (dns queries; depends how your DNS is set up).
That's just best practice.



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[PcLinuxGuru]

Thanks SGTB I learn something every day

 

[Psychoid]

Hi there.
GNAT is a good firewall.
It's especially nice because it boots from a floppy & can really run on any old piece of junk box.

I have to admit that I haven't touched GNAT for a couple of years, but I think that I can answer your question.

General practice with firewalls is:
Open what's necessary and deny all else

This means that you should set up rules to open the necessary ports and then to deny all other incoming traffic.

Your firewall rules should be in accordance with the corporate security policy. In very general terms, though, many companies have the following ports open for incoming traffic:
80 for access to the web server
443 for secure access to the web server
21 for access to the FTP server
25 for incoming email

Of course, these are common and are not indicative of all businesses. The ports that you open should be dictated by your corporate security policy.

Here is a hypertext link to the official document of all the common port numbers:

http://www.iana.org/assignments/port-numbers

Hope that helps


------------
Bill
Consultant / Network Engineer
CNE, CCNA

 

[PalmStrike]

Yes, thanks for your responce, I think that is what we have here, but to be brutally honest, I am our corporate security policy. and I am trying to secure the network as the boss set it up about 3 years ago, but is unaware of how it actually works, hence, i have found huge holes internally, and just wanted to get an idea if there are any externally. thanks for your help.

Kind regards
Rob