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NTBugtraq And NTSecurity Archives: DNS and TCP/IP security

DNS and TCP/IP security

Subject: DNS and TCP/IP security
From: Matthew Spool (matthewsLOGICALCONSULTING.COM)
Date: Tue Dec 14 1999 - 14:19:30 CST

I'm having some problems getting DNS to work correctly when configuring NT
TCP/IP security. I'm restricting TCP ports to 80 and 443, UDP ports to 53,
and IP Protocols to 6 and 17. For some reason, my machine will no longer
resolve host names. I have no problems connecting with IP addresses, but
when I try to connect with host names, it always times out. For example, I
cannot get to any web page using the URL (the browser times out trying to
find the site), but as soon use the IP address of the site, the browser
connects immediately. As soon as I switch TCP and UDP ports back to "Permit
All", name resolution occurs without a problem. I have also tried it
allowing TCP port 53 as sometimes DNS will use TCP instead of UDP. This is
on an NT server (not the DNS server) running NT 4.0 SP6a. The DNS server is
a NT DNS server (unknown SP level) and there are no port restrictions set on
it. I haven't run Netmon yet, but that's my next step. I have been able to
reproduce this problem on several systems but have not been able to find a
fix besides enabling all ports. Can anyone help?

Thanks,
Matt Spool

This archive was generated by hypermail 2b27 : Tue Dec 14 1999 - 20:11:19 CST