topic Re: telnet problem in Operating System - HP-UX

telnet problem

Fadia Almarei — Tue, 02 May 2006 10:40:39 GMT

Dear All
I have HP-UX 11.11 Os on rp5430 server,first I have no problem in my network, I try to telnet to the server it takes long time until I get any response,I try to ftp to it ,it does not responed, I then restart it nothing happened , where the problem may be and how could I solve it.
BR;

Re: telnet problem

Steven E. Protter — Tue, 02 May 2006 10:47:33 GMT

Shalom fadia,

Most usual problem here is DNS response./

Look up the ip address of the system and use that instead of hostname

telnet hostname
becomes
telnet 192.168.0.10

if indeed the response to a numeric connect if faster, its a Name resolution issue.

check /etc/nsswitch.conf host resolution and see if files or dns is first

if files is first, install support for the hostnames you connect to in /etc/hosts

You may wish to do this anyway as a backup.

If you prefer dns resolution, then check the zone records and see that there is a record for the server.

DNS involves these files:

/etc/resolv.conf # what servers resolve names, this may require change.
/etc/named.conf # runs bind/named daemon if running
/etc/nsswitch.conf
/etc/hosts # if refferred to in nsswitch.conf

If nsswitch.conf does not exist there are several copies after install. nsswitch.nis nisswitch.files etcetera.

Pick the one you think works best with your networking and make it via cp or mv /etc/nsswitch.conf

SEP

Re: telnet problem

Fadia Almarei — Tue, 02 May 2006 10:53:03 GMT

hi Steven , no dns problem i try it using IP address and hostname but i have the same problem

Re: telnet problem

Procnus — Tue, 02 May 2006 21:27:58 GMT

We had similar problems where I work. It turned out that it wasn't the resolution of the server name that was a problem, the delay was caused by the server trying to resolve the IP address of the PC we were telnetting from.

I would suggest trying to resolve the IP address of your PC on the rp5430. Our workaround until the DNS was sorted out was to modify /etc/nsswitch.conf to read:
hosts: files [NOTFOUND=return UNAVAIL=continue] dns [NOTFOUND=return UNAVAIL=continue TRYAGAIN=return]

Once the DNS was sorted the return in files was changed to continue.

Cheers
Steven

Re: telnet problem

Bill Hassell — Tue, 02 May 2006 22:04:46 GMT

Steven has defined the problem correctly. Your HP-UX server is trying to prevent intrusion from spoofed IP addresses by consulting DNS as to the validity of the telnet client. Most PCs are assigned a DHCP address but the DNS administrator did not implement dynmaic DNS or otherwise assign names to the DHCP pool of addresses. Therefore, the telnet daemon looks up the address of the PC and the DNS server says "I never heard of this address". By putting all the addresses in the DNS pool into /etc/hosts (with names), the delay will disappear. Otherwise, have the DNS admin cover the DHCP pool addresses.