Re: telnetd slow to respond

[Andrea Vettorello <molotov@dei.unipd.it>]

Patrick Colbeck wrote:

> Yup
>
> I think the telnetd tries to do a reverse lookup on the incoming telnet
> session. Adding your ip address and machine name to the hosts file of the
> machine you are telneting to will speed it up a lot. Same thing applies to
> proftpd so maybe its a function of the inetd super server ?
>

I'm not sure, but i think it's related to the default setting of
/etc/hosts.deny, where you will find the line ALL:PARANOID.

The PARANOID option will try to do a reverse lookup of the incoming connection
to check if the name and address are matching.

The thing that puzzles me is: why the connection is not refused if the DNS
doesn't return the name?

This could happen, for example, in a local network when the lazy admin don't
configure the DNS with the proper local zone and contacts another box only with
the numeric IP, and yes, this was my lame behavior some time ago: painly slow
remote login every time!  =)   (now, with the DNS properly configured no more
slowdown)


Andrea