slow telnet connections

Mike Roest bind at blahz.ab.ca
Tue Aug 27 13:11:44 UTC 2002


I'm guessing that your linux server is attempting to perform a reverse 
lookup on the windows's machine IP, and to do this it is going through 
your resolver list in /etc/resolv.conf.  Usually when your connection is 
up it can run through your names server list quickly and then give the 
login prompt when it can't find a reverse entry. The easiest fix is just 
add an entry for your windows box to /etc/hosts since the telnetd will 
lookup reverse in the hosts file as well as through DNS. The better way 
around this is to install a local nameserver that has a proper reverse 
zone for 192.168.0/24 and modify your resolv.conf to

nameserver 127.0.0.1
....rest of nameservers

This will allow the linux server to get the reverse entry quickly 
whether your internet connection is up or down.

If you dont want the local nameserver looking up all queries, just set 
it so it forwards all non local requests to your ISP's name servers.

--Mike
Kostis Mentzelos wrote:
> Hi all,
> 
> 
> My problem is that after I configure /etc/resolv.conf file I experienced
> very slow telnet connections.
> 
> 
> (some times it is impossible to connect or it takes more than 30 minutes to
> prompt login
> 
> although I am using IP addresses not names. When I am trying to telnet from
> linux box to
> 
> my linux server there is no problem)
> 
> 
> The problem occurs when the internet connection is down therefore the name
> server
> 
> cannot be accessed and I am running telnet from a window pc.
> 
> 
> linux server IP: 192.168.0.1
> 
> windows pc IP: 192.168.0.101
> 
> 
> from windows command prompt: telnet 192.168.0.1
> 
> 
> My question is why while I am using LOCAL IP addresses linux server needs to
> query the dns server?
> 
> 
> Do you have any idea?
> 
> 
> Thanks in advance,
> 
> Kostis Mentzelos
> 
> 
> 
> 
> 
> 
> 
> 



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