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SSH and Telnet question

 
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Chris Fadrowski
Super Advisor

SSH and Telnet question

I have multiple rx4640 Itanium systems running HPUX 11.23v2. On one particular system, when telneting or shh'g to or from the system it takes up to 20 seconds for the username prompt to appear.

All the other systems are instantaneous with the prompt. Each system is relatively the same. I am wondering why this one system is perfroming like this.

it is causing timeouts with applications that log in to the system. Any ideas?
11 REPLIES 11
DCE
Honored Contributor
Solution

Re: SSH and Telnet question


most likely cause - DNS

check nsswitch.conf
check name lookup
check reveres name lookup

Highlighted
Reshma Malusare
Trusted Contributor

Re: SSH and Telnet question

Hi chris,

Its a hostname resolution problem.. system is taking time to resolve the host name from cache.When a program on a client host needs to obtain information about a domain, it will send a message to the local DNS server host. If the local server has this information, it will send back a reply immediately. If the local server does not have this information, it will research by sending queries to other servers, following the Domain Name System structure. Once the local server has found an answer for the client, it will then reply, but will also cache what it has learned in order to respond more speedily to subsequent queries.
Check ur /etc/hosts..

Check for --->

nslookup â query Internet name servers interactively

dig â Domain Information Groper

host â look up host names using domain server

addr â get address of host

dnsquery â give all the DNS details and Mail exchange records

As suggested above check /etc/nsswitch.conf
--> configuration file for the name-service switch

Thanks & Regards
Reshma
Sandman!
Honored Contributor

Re: SSH and Telnet question

If you suspect DNS then try telnet'ing to the server with the numeric IP address instead of the symbolic name. If this gives you an "instantaneous" prompt then DNS is the culprit otherwise rummage thru the network to isolate the problem.
Chris Fadrowski
Super Advisor

Re: SSH and Telnet question

that's just it. it does this to and from. Even if i use the IP address its still delayed. that's why i didn't look at DNS.

here is my nsswitch.conf

hosts: dns [NOTFOUND=continue UNAVAIL=continue TRYAGAIN=continue] files [NOTFOUND=return UNAVAIL=continue TRYAGAI
N=return]

its participating on the network just fine. No one is complaining of poor performance.
Ivan Krastev
Honored Contributor

Re: SSH and Telnet question

Chris Fadrowski
Super Advisor

Re: SSH and Telnet question

UseDNS is commented out in the sshd_config file already.


#UseDNS = yes
Ivan Krastev
Honored Contributor

Re: SSH and Telnet question

It's commented, but default value is Yes.

regards,
ivan
Sandman!
Honored Contributor

Re: SSH and Telnet question

You could try tracing the telnet/ssh login process thru tusc and see where it hangs viz.,

# tusc hostname
Chris Fadrowski
Super Advisor

Re: SSH and Telnet question

what is "tusc"