Date: Thu, 24 Sep 1998 13:52:54 -0500 (CDT) From: Mark Murdock <fee@tetrahome.tetranet.net> To: Mike Tancsa <mike@sentex.net> Cc: stable@FreeBSD.ORG Subject: Re: resolving ips? Message-ID: <Pine.BSD/.3.91.980924133354.7245A-100000@tetrahome.tetranet.net> In-Reply-To: <3.0.5.32.19980924022527.00d10bb0@sentex.net>
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On Thu, 24 Sep 1998, Mike Tancsa wrote: > At 09:04 PM 9/23/98 -0500, Mark Murdock wrote: > >Yet another question for freebsd-stable network experts: > > > >When I try to telnet to an ip address, my system attempts to contact my > >name servers in my /etc/resolv.conf file. I was actually unable to telnet > >to an ip due to this when my ipfw configuration was blocking udp on 53. > > Just give it time... It will work eventually. The system you are trying to > telnet to is trying to lookup the name of the host you are coming from so > it can log it. I have to disagree here. My name server is fully functional (as it remains outside of my local network) and could respond to reverse lookups without problem. I was watching the packets on my ppp interface, and what I was seeing was MY machine making DNS requests to MY DNS server. I was blocking these requests of course, so it was hanging, but it was the fact that it even consulted a domain name server that was interesting me. > > > >Why consult the resolver? Why not just make your connection based on the > >kernel routing tables? > > I am not sure what you mean by the routing table in this case.. What you > are describing is a DNS timeout...If you want it to work faster in this > situation, then change /etc/host.conf to list hosts first, then bind and > add the necessary information in your /etc/hosts file. > To clarify the routing table issue, I'll explain what I meant by that. If I type "telnet 10.1.1.1", I would not expect telnet to consult a DNS server to do a reverse lookup on that IP. I would expect it to consult the routing table, decide that 10.1.1.1 was either on a local subnet, through a remote gateway, or through the default route, and route my TCP SYN packet accordingly. By mentioning routing, I only meant that to ME, that was the logical step after receiving an IP address. Had I give it a host name, I would have EXPECTED it to consult DNS, and then route to the resulting IP accordingly. I hope this sheds some light on what I meant. I just think it's odd that an application like telnet does a reverse lookup on an IP. I would rather see those applications work independant of DNS when given an IP, but perhaps that's not going to happen. Mark > ---Mike > ********************************************************************** > Mike Tancsa, Network Admin * mike@sentex.net > Sentex Communications Corp, * http://www.sentex.net/mike > Cambridge, Ontario * 01.519.651.3400 > Canada * > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-stable" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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