Hi Edison, Arul (GE Healthcare)!

 On 2014.05.27 at 10:06:10 +0000, Edison, Arul (GE Healthcare) wrote next:

> Hi All,
> 	In my system, I want to provide telnet feature and hence I installed the telnet rpms . however I found that , when connected from another system with telnet command, it takes 30 mins to show the telnet login prompt.
> 	Is there any configuration needed to be performed to make the telnet fast?
> Many Thanks,

I really hope you are using telnet for testing connectivity or text
protocols or similar tasks, not as remote shell, because it's extremely
insecure..

First, check if you have krb5-appl-clients package installed. If you
have and you aren't using kerberos, remove it (actually, it's safe to
remove even if you are using kerberos for some common tasks like nfs
auth).

If you don't have it installed but telnet still is very slow, then
problem lies elsewhere. First of all, check if DNS is working correctly;
check resolver configuration (/etc/resolv.conf, /etc/nsswitch.conf) for
something strange; try using "telnet" with IP address (AFAIK telnet
shouldn't try to do reverse DNS resolving).

If DNS and resolver configuration are correct, there might be problem
with network or firewall. Check if telnet work with other host, e.g.

$ telnet google.com 80
Trying 2a00:1450:4010:c03::66...
Connected to google.com.
Escape character is '^]'.
GET / HTTP/1.0 

HTTP/1.0 302 Found
...

(here, you type "GET / HTTP/1.0" and press "enter" twice after getting
"Escape character is" message - and you should get a reply right away).

If it works but telnet to your host still gives you a problem, there
might be something else, like problem at remote side. Like, for example,
remote host is trying to resolve your IP again and again until it
finally gives up, or there is some other strange logic at play. Best way
to solve these problem is to analyze tcp stream (with tcpdump or
wireshark), best if you can gather it both at client and server. Either
way, these kinds of problems fall into "remote side gives you 30 min
delay" category, it's not really a problem with "telnet" application per se.

-- 

Vladimir