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Hi, I have a PC which was running Ubuntu 6 and I use PuTTY on a Windows box to ssh telnet into the linux machine. This has worked fine.
Now, I upgraded to Ubuntu 7, and now when I ssh in via Putty, the login takes about 5-6 seconds before I get the password prompt. I have PuTTY configured to specify the username, so I see:
Using username "xyz"
immediately (I don't know if that ssh or putty printing that...)
and then about 5-6 seconds later, I get the password prompt.
This is annoying to me because I routinely open/use/close these telnet sessions on a rapid basis.
How can I log the ssh login process to see what's causing the delay?
Any help would be appreciated.
Note: I did not change my PuTTY configuration, so it must be something related to the new Ubuntu that's causing the delay. Also, if I just type "ssh localhost" from the linuxpc itself, I don't see the delay. Also, from my windows pc, I can ping the linux pc with a turn around time of 0.02 seconds, so the basic connection is fine.
I installed wireshark on the linux pc and did a capture of this time period.
I see some ssh init, key exchange, diffie-hellman somethingorother, and encryped response packet all within .15 seconds.
Then there is: (time proto info) [time ref is first ssh message]
0.15 DNS "Standard query PTR <windows_ip>.in-addr.arpa"
0.15 DNS "Standard query response, No such name"
0.25 MDNS "Standard query PTR <windows_ip>.in-addr.arpa"
1.26 MDNS "Standard query PTR <windows_ip>.in-addr.arpa"
3.26 MDNS "Standard query PTR <windows_ip>.in-addr.arpa"
5.15 SSHv2 Encrypted response packet
I'm not terribly familiar with reverse DNS - is that what this is? It seems after the first DNS failed, then it tried multicast DNS whatever that is - apparently with no response.
he shoots... he scores! right so either look at setting up a local dns server (very very easy with dnsmasq), add details to /etc/hosts on the server machine so they know who the client is, or set UseDNS=NO in your sshd_config file