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sungiant
Asked: 2014-07-03 01:45:40 +0800 CST

SSH remote commands very slow after migrating from 12.10 to 14.04 on EC2

  • 772

I had a number of 12.10 machines running on EC2 and provisioned them using scripts built around:

  • ssh
  • scp
  • rsync

Now I have replaced most of my 12.10 machines with 14.04 machine and am finding that my provisioning scripts now run prohibitively slowly whilst executing the same remote commands.

An example of a remote command being used is:

ssh -o StrictHostKeyChecking=no -o BatchMode=yes -p22 -i /Users/.ssh/ec2_key.pem [email protected] "sudo /etc/init.d/redis-server status"

This will execute very quickly on my 12.10 machines, maximum 3 seconds delay, however the same command on the 14.04 machines can take upwards of 60 seconds.

Does anyone know what the problem is?

Watching the machine through htop whilst running a remote command indicates that the problem is somehow related to the message of the day:

enter image description here

12.10

1 Answers

  1. Best Answer

    Um, I think you'll find that your server is triggering a message of the day update upon an established ssh connection.

    You can run the scripts in /etc/update-motd.d and see which is running slowly and deal with the slow script however you wish.

    Or you can disable this automatic updating by commenting out the following lines in the /etc/pam.d/sshd file

    session    optional     pam_motd.so  motd=/run/motd.dynamic noupdate
session    optional     pam_motd.so # [1]
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