Date: Thu, 30 May 1996 22:17:51 +0100 (BST) From: Nik Clayton <nik@blueberry.co.uk> To: questions@freebsd.org Cc: nik@guava.blueberry.co.uk (Nik Clayton) Subject: NIS and usage of /etc/hosts Message-ID: <199605302117.WAA01200@guava.blueberry.co.uk>
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How do,
Short question:
With NIS running on a local network, a name service running, but no
reverse DNS, telnet'ing to another machine on the local network pauses for
2 minutes will the in-addr.arpa lookups time out. Why isn't the
hosts.byaddr map used?
Long question (as above, but more depth, for those with time):
I've got two machines, A and B.
I'm in the process of installing NIS on the two of them. A is the master,
B is the client.
Up until I started doing this, both machines had identical /etc/passwd,
/etc/hosts and /etc/host.conf files.
I think I've got NIS running successfully. Certainly the passwd maps are
going across successfully, because I can login to B as one of the users on
A, when that user only exists in the NIS map, and definitely not on B's
/etc/passwd file.
I'm in the final throes of finishing this configuration. After reducing
the password file on B, I figured it was time to reduce the /etc/hosts
file as well.
So I pulled it down to it's bare essentials, namely an entry for 'localhost'
and an entry for 'B' itself.
Then I edited /etc/host.conf, and set the lookup order to
hosts
nis
bind
My reasoning being 'use /etc/hosts for yourself and localhost, nis for
anything on the local network, and the DNS for everything else' which
seems sensible.
And now, telnetting from A to B takes 2 minutes longer than normal. If I
put a line for A into B's /etc/hosts file then I can telnet in straight
away. So far, this smells like a name resolution problem.
After theorising with a friend, we decided that telnetd (and others,
because this behaviour is exhibited with rlogin) is doing a reverse lookup
on A's IP address to get the name, to put it into things like {w,u}tmp and
the like. Because we don't have any reverse DNS (it's a long story)
Acting on this, I commented out the 'bind' entry in /etc/host.conf and
tried again. Our theory seems to be correct, as now A's IP address is put
into the {w,u}tmp records, and the connection starts at the usual speed.
Of course, now B can't do name lookups, which isn't very useful.
This feels like telnetd (and friends) aren't using the host.byaddr NIS map
to turn the IP address into a name. Why?
Or am I barking up completely the wrong tree?
N
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