[SOLVED] Different SSHs

Jason.nix · 01-20-2024, 01:53 AM

Hello,
Is the SSH configuration file different for each user?
I want to have two SSH users. One of them can have two sessions at the same time and one can have only one session. Is this possible?

Thank you.

lvm_ · 01-20-2024, 02:35 AM

It can be done but not via sshd configuration. man limits.conf, man pam_limits

pan64 · 01-20-2024, 02:56 AM

you might even start 2 different ssh servers with different configs.

Turbocapitalist · 01-20-2024, 03:29 AM

Quote:

Originally Posted by Jason.nix

Is the SSH configuration file different for each user?
I want to have two SSH users. One of them can have two sessions at the same time and one can have only one session. Is this possible?

Yes, it can be different for each user if you set that with the Match directive. When combined with the MaxSessions directive you can limit the number of concurrent remote logins. However, keep in mind that there are a great many ways to circumvent that once they are logged in. For example, with shell access they could log in and run tmux or screen and thus have multiple interactive sessions via a single SSH session.

What problem are you trying to solve?

replica9000 · 01-20-2024, 09:47 AM

You can add this to the user's ~/.ssh/config if you want to limit them to one connection if they open more than one session

Code:

Host *
   ControlMaster auto
   ControlPath ~/.ssh/sockets/%r@%h-%p
   ControlPersist 600

ControlPath can by anything, but the directory has to exist before hand. SSH won't create it on its own.

Jason.nix · 01-21-2024, 12:53 AM

Quote:

Originally Posted by lvm_

It can be done but not via sshd configuration. man limits.conf, man pam_limits

Hello,
Thank you so much for your reply.
The syntax is:

Code:

<Username> <type> <item> <value>

I found some interesting fields for <item>:

Code:

     core
         limits the core file size (KB)

     data
         maximum data size (KB)

     fsize
         maximum filesize (KB)

     memlock
         maximum locked-in-memory address space (KB)

     stack
        maximum stack size (KB)

     cpu
        maximum CPU time (minutes)

Can I limit the amount of RAM and CPU usage for the user?

lvm_ · 01-21-2024, 01:43 AM

Quote:

Originally Posted by Jason.nix

Can I limit the amount of RAM and CPU usage for the user?

As far as CPU and RAM usage are concerned pam_limits controls per process usage, not a per user one. You should use cgroups for that.

Jason.nix · 01-21-2024, 04:47 AM

Quote:

Originally Posted by lvm_

As far as CPU and RAM usage are concerned pam_limits controls per process usage, not a per user one. You should use cgroups for that.

Hello,
Thank you so much.