While I don't know about Compuserve, I've done some research on AOL.
When using it through TCPIP, you will need to allow outgoing TCP
connections to port 5190, to the host aol.americaonline.com. (even AOL
email will go through this port, and be converted to SMTP on the remote
end if need be).
Of course, this hostname has multiple IP addresses assoiciated with it,
so Jens' suggestions would apply. However, I wouldn't suggest letting
your firewall trust untrusted name servers out on the net for purposes
of figuring out which external hosts should be connected to - this is a
security risk. I would always use the "nslookup" method, and hardcode
these ip addresses into your firewall security policy.
Jens Andersen wrote:
> It is not clear whether AOL and CompuServe use unique ports for all
> traffic: For instance, sending AOL e-mail is likely to use SMTP port
> which you may not want to disable.
> A sure way would be to test for destination.
> For instance, it's known that CompuServe users accessing it via
> Internet connect to gateway.compuserve.com. Similarly, AOL users will
> probably make connections to certain computers in aol.com domain.
> If a filter was intelligent enough to recognize domain names vs. IP
> ports or IP numbers, you could program "aol.com" into it. In your
> case, you can do NSLOOKUP on gateway.compuserve.com and enter all IP
> resolutions for that address (possibly only one) into your filter.
> I just tried it:
> C:\>nslookup gateway.compuserve.com
> Name: arl-gw06.compuserve.com
> Addresses: 126.96.36.199, 188.8.131.52, 184.108.40.206,
> 220.127.116.11, 18.104.22.168, 22.214.171.124,
> 126.96.36.199, 188.8.131.52, 184.108.40.206,
> 220.127.116.11, 18.104.22.168
> Aliases: gateway.compuserve.com
> Alternatively, you could use software designed to recognize domains by
> name and block traffic on this criteria. LittleBrother
> http://www.littlebrother.com is one such product.
> Good luck with your task,
> Jens Andersen.
> On 10 Apr 97 at 15:28, Dennis Fanshaw wrote:
> > Date: Thu, 10 Apr 1997 15:28:07 -0400
> > From: Dennis Fanshaw <dfanshaw @
> > To: firewalls @
> > Subject: questions about AOLand Compuserve software port use.
> > Can anyone tell me what port numbers the AOL and compuserve software
> > uses when accessing thier services over the internet???
> > I'm working on some packet filters for a client and I know they have a
> > few users making use of the AOL and compuserve software.
> > Thanks,
> > Dennis Fanshaw
> > dfanshaw @
> Jens Andersen/Sales Manager
> Kansmen Corporation
> Tel: 408.263.9881 ext 107 Fax: 408.263.9883
> http://www.kansmen.com E-mail: jens @
> 546 Valley Way, Milpitas California 95035, USA
> See CNN's and c/net's review of LittleBrother:
> Hot Seat interview about LittleBrother:
> Go make it a great day!
Brian Connolly brian @
Business Development Engineer 415.562.0400, ext 252
Check Point Software Technologies fax 415.562.0410