Set SSH connection timeout

Question

I'm trying to cut down the time ssh is trying to open a connection to a host. If I put for example ssh www.google.com it takes very long until the prompt comes back.

I read about using ssh -o ConnectTimeout=10 www.google.com instead, but even this takes very long. Is there maybe a number of attemps I can modify to decrease the blocking time?

Answer 1

The problem may be that ssh is trying to connect to all the different IPs that www.google.com resolves to. For example on my machine:

# ssh -v -o ConnectTimeout=1 -o ConnectionAttempts=1 www.google.com OpenSSH_5.9p1, OpenSSL 0.9.8t 18 Jan 2012 debug1: Connecting to www.google.com [173.194.43.20] port 22. debug1: connect to address 173.194.43.20 port 22: Connection timed out debug1: Connecting to www.google.com [173.194.43.19] port 22. debug1: connect to address 173.194.43.19 port 22: Connection timed out debug1: Connecting to www.google.com [173.194.43.18] port 22. debug1: connect to address 173.194.43.18 port 22: Connection timed out debug1: Connecting to www.google.com [173.194.43.17] port 22. debug1: connect to address 173.194.43.17 port 22: Connection timed out debug1: Connecting to www.google.com [173.194.43.16] port 22. debug1: connect to address 173.194.43.16 port 22: Connection timed out ssh: connect to host www.google.com port 22: Connection timed out 

If I run it with a specific IP, it returns much faster.

EDIT: I've timed it (with time) and the results are:

• www.google.com - 5.086 seconds
• 173.94.43.16 - 1.054 seconds