What does the options `ServerAliveInterval` and `ClientAliveInterval` in sshd_config do, precisely?

Question

I found this question, but I'm sorry I don't quite understand the settings on the two variables ServerAliveInterval and ClientAliveInterval mentioned in the accepted response. If my local server is timing out, should I set this value to zero? Will it then never time out? Should I instead set it to 300 seconds or something?

My question is simply, some of my connections time out when I suspend & then unsuspend my laptop with the response Write failed: Broken pipe and some don't. How can I correctly configure a local sshd so that they don't fail with a broken pipe?

Answer 1

ServerAliveInterval: number of seconds that the client will wait before sending a null packet to the server (to keep the connection alive).

ClientAliveInternal: number of seconds that the server will wait before sending a null packet to the client (to keep the connection alive).

Setting a value of 0 (the default) will disable these features so your connection could drop if it is idle for too long.

ServerAliveInterval seems to be the most common strategy to keep a connection alive. To prevent the broken pipe problem, here is the ssh config I use in my .ssh/config file:

Host myhostshortcut
     HostName myhost.com
     User barthelemy
     ServerAliveInterval 60

Answer 2

You could also run commands with nohup if you want them to run regardless of your SSH connection.

e.g.

$ nohup tar -xzf some_huge.tar.gz &

The & is, I think, not necessary, but it is convenient since it makes the process run in the background so you can do other stuff.

I always use nohup for any process that takes awhile, so that I don't have to start over if I lose the connection for whatever reason - power outage, network outage, whatever.