ssh + along delay after typing the password between win to linux

Question

I installed two Linux machines with Linux version - 5.5.1.0-01

Something is very strange if I perform ssh between Linux to Linux after I type the password I get the prompt of the second Linux machine without any delay

But if I perform ssh from window VIA (putty/reflection) to the Linux machines , after I type the password I have a long delay like 6 seconds

so please advice why I get delay when I connect to linux machine from windows

and I not get any delay when I perform ssh between Linux machines

Remark I have two Linux machine – 5.5 version + PC with windows XP all machines connected to the switch with 1G speed

Answer 1

The main cause of that sort of delay in ssh is DNS resolution of the client. On the ssh server, can you not do a reverse lookup of the Windows client machine's IP address? Does the same lookup work for the Linux clients?

If that's the case, add the following line to the /etc/ssh/sshd_config of the server to disable the DNS lookup of the IP address:

UseDNS no

You can also take a look at the OpenSSH FAQ entry for this sort of problem: http://www.openssh.org/faq.html#3.3

Answer 2

Usually this problem arises due to the 'Reverse DNS Lookup' the SSH daemon performs on the connection client ip. To disable this reverse dns lookup add to your sshd-configfile the following line:

UseDNS no

disabeling the reverse DNS shouldn't impact your standard security parameters at all.