[ale] Connection From 192.168.1.x Requires Host Name

[Ben Coleman]

On Sun, 19 Jan 2003 14:49:24 -0500, Mike Millson wrote:

>Given:
>Linux server: 192.168.1.1
>Windbloze machine: 192.168.1.10
>
>When I try to ssh or send mail to my Linux server from my windbloze machine,
>it takes about a minute to connect unless I add an entry for 192.168.1.10 to
>the Linux server hosts file. With the hosts name entry, the connection
>happens right away.
>
>Evidently ssh and sendmail do a reverse DNS lookup or something that causes
>a big delay if there is no entry in the hosts file? Can someone explain what
>is happening and why this is so?

The reverse lookup is the most likely explanation.  Sendmail typically
*does* do a reverse lookup on the client for the 'Received:' line, and
I wouldn't be surprised if thessh server does it for logging purposes. 
Since 192.168.*.* is 'reserved', there is no server out there to handle
the reverse lookup, and the program waits until the lookup times out. 
Your Linux server is probably configured to check the hosts file first
before doing a DNS query, so putting the hosts file entry in gets rid
of the timeout.

>Also, if the Windbloze address is assigned via DHCP, do I have to put a host
>name for every possible IP address in the assignment block I'm using? This
>seems too hard. Any suggestions?

Ask Fletch whip up a quick Perl one-liner to generate all of the hosts
entries you'd need :-)

For real overkill, run BIND 9 on your Linux server, make it think it's
authoritative for the reverse DNS domain that covers the block of
addresses that DHCP hands out, and use $GENERATE to populate the DNS
entries for the block.  You'd end up with a local caching DNS server,
to boot.  But this is probably more than you'd want to do just to solve
this problem.

Ben
-- 
Ben Coleman oloryn at benshome.net      | The attempt to legislatively
http://oloryn.home.mindspring.com/   | micromanage equality results, at
Amateur Radio NJ8J                   | best, in equal misery for all.


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