Re: Slow telnet/pop3 connection

On Sat, 26 Apr 2008, in the Usenet newsgroup comp.os.linux.networking, in
article <1q1814l1ckc6igc6tqct2eojej8thchesn@xxxxxxx>, Mark Olbert wrote:

I'm transitioning to a new linux server (based on linuxfromscratch) and
have noticed a significant deterioration in connection time for telnet
and pop3 connections, but not ssh connections (all using the same
"telnet" client on some Windows Vista boxes).

Are "all" of the connections slow, or just the initial one (takes a LONG
time to get a login prompt, but once you get that, things are at normal
speed)?

What's weird is that similar connections made to the old linux server
-- which is plugged into the same switch -- are still quite fast.

So, what is the difference in the configurations? If the "new" box
is using xinetd to run the effected services, and the "old" box is
running the old inetd, you may be causing the problem by the "Log"
lines in the individual service files (something lacking in inetd).
This could also be caused by the new server attempting to use 'auth'
(RFC1413 using tcp/114) if your clients are "DROP"ing such requests
rather than answering or "REJECT"ing those requests. A packet sniffer
would show this instantly.

I've read that this typically involves problems with reverse DNS
lookups, but I tried using IP adddresses on the telnet client, rather
than names, and it's just as slow.

The DNS lookup occurs on the _server_ not the client. The server wants
to know the name of the system connecting. It does this by attempting a
reverse (PTR) lookup. If your DNS can not resolve the PTR query, you
need to have the individual names/addresses of ALL clients in the
/etc/hosts file on the server.

Old guy
.

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