topic Re: Telnet become slower in Operating System - Linux

Telnet become slower

george_114 — Fri, 19 Dec 2003 22:15:21 GMT

At the beginning, if i telnet to my linux server, it prompt to linux login very fast but after 3 months, it becomes slower to prompt to linux login.Why does this happen??

Re: Telnet become slower

Martin P.J. Zinser — Fri, 19 Dec 2003 22:50:19 GMT

Hello George,

does a reboot 'fix' the problem? If so you might have a resource leaking on the system. The most obvious being memory, does top show
different memory usage before and after a reboot?

Greetings, Martin

(P.S. Testing this might be difficult if it always takes 3 months to show up. OTOH the problem in that case is not that bad :-)

Re: Telnet become slower

Huc_1 — Sat, 20 Dec 2003 06:44:35 GMT

Yes it could be a memory leak .. or a network issue .

try traceroute and ping from linux to other
and
traceroute and ping from other to linux
then compare.

Martin what does OTHO mean ?

J-P

Re: Telnet become slower

Martin P.J. Zinser — Sat, 20 Dec 2003 10:28:58 GMT

Hello Huc,

IIRC (If I remember correctly) OTOH = on the other hand, i.e. looking at an issue from another angle. Obviously YYMV (Your mileage might vary) concerning acronyms. I am certainly not ROTFL (Rolling on the floor laughing) since I use ESL (English as a second language) too.

HTH (Hope that helps) ;-)

Martin

Re: Telnet become slower

Steven E. Protter — Sat, 20 Dec 2003 21:02:28 GMT

Most common cause here is actually the DNS server.

If there has been a change to it with regards to the Linux server or the client you are using to log on isn't pointing to a current DNS server, this could cause the problem.

Also DNS servers running on Windows NT are notorious for this kind of problem. The fix there is Windows 2000 or Linux as the DNS server.

SEP

Re: Telnet become slower

Vitaly Karasik_1 — Sun, 21 Dec 2003 05:02:11 GMT

Agree with Steven - it's DNS problem.

You should check if "telnet server" has regular/reverse DNS for clients.

Rgds,
Vitaly

Re: Telnet become slower

Martin P.J. Zinser — Mon, 22 Dec 2003 10:39:36 GMT

Hello,

if DNS/name lookup is the problem the change should have happened at one particular point in time, not gradually over three months.Which of this is the case the original poster should know ;-)

Greetings, Martin

Re: Telnet become slower

K.C. Chan — Tue, 23 Dec 2003 09:27:47 GMT

We can determine if is a dns issue just by telneting to it via ip address. If this is still slow, then the problem may not be DNS related.

have you considered at the time you telnet to the server, that either server may be under haevy load? Have you checked that both end of the server have proper dns resolution entries in /etc/resolve.conf file? Is the problem on related to this target host or telnet is just slow everywhere you telnet to?

Re: Telnet become slower

Martin P.J. Zinser — Tue, 23 Dec 2003 10:47:58 GMT

Hello K.C.,

sorry no, the test you suggested will not show if DNS is the problem or not. Since the server most probably tries to resolve the clients address it does not matter if you use a name or ip address in the client.

Greetings, Martin

Re: Telnet become slower

K.C. Chan — Tue, 23 Dec 2003 13:30:08 GMT

OK, forgotten about how the server will react, just trying to isolate where the cause of the problem, one of the things I try to determine is if it is the server or the client. Let say the server is 192.168.100.1, on the client and the server can you do an nslookup on it. Can you make sure in your nsswitch.conf file that dns is the first to be use to resolve name lookup. Can you also make sure that your entry in /etc/resolv.conf file is correct.