DNS and port filtering

[Phil]

I am port filtering and I can't acces internet with Alpha
names. IF I use IP address, all is well. I have
added "permit only" port 53 and 80 to UDP and TCP. Is
there another port I am missing? Is the network stack
damaged?

 

[Guest]

Need more information. what is your firewall? What is
the service you are trying to permit?

 

[Karl Levinson [x y] mvp]

Check your logs. If there are no logs [like you're using native Windows
2000 tools to do the filtering], use a real third party filtering solution
like a firewall that has logging [or a free sniffer like Ethereal].

 

[Steven L Umbach]

Ip filtering is used to control inbound traffic only, so unless you are
hosting a website or dns server, you are not using it for the right purpose.
My experience is that ip filtering will allow inbound tcp return traffic to
initiated outbound traffic, but not for udp which means that your dns server
responses from your dns name resolution requests are being blocked. I
suggest you use a firewall instead, such as the free ones availabe foe
personal use from Sygate, Kerio, or Zone Alarm. --- Steve

http://www.webattack.com/Freeware/security/fwfirewall.shtml

 

[Phil]

All I want to do is browse the internet. Also, this is a
test box which I am trying different mail server apps. Of
course I would add port 110 and port 25. I was hoping to
keep the configuration as simple as possible, ie...no
firewall or router, thus the reason for port filtering.
Somehow, I can't get get results for my DNS queries. Is
port 53 all that is needed for DNS? I will also look into
the sniffer. BTW I am using win2k adv server. Thanks all
for the replies.