How to limit the number of port forwarding connections - ssh

mhn2

12/20/23, 1:07 PM

I have a user on my linux server which is used for proxy. Currently the shell access and a lot of other features are disabled and the following command will be used on it:

ssh proxy-user@server -D 1080 -N

However recently I decided to put a limit on the number of simultaneous connections.

I've tried limits.conf and MaxSessions, but none of them can deal with the ssh -N argument. They won't count these types of connections for the limit.

Is there anyway for me to limit the number of connections that are only using port forwarding (using the -N argument)?

Notes:

No I can't use a socks server such as dante
I can't limit the total number of connections for all the users because I don't want to apply the limit for other users
Here is the current limitations for the proxy user:

Match User proxy-user
   AllowTcpForwarding yes
   X11Forwarding no
   PermitTunnel no
   GatewayPorts no
   AllowAgentForwarding no
   PasswordAuthentication yes
   ForceCommand echo 'This account can only be used for socks proxy'

441

0 + 2

ssh

diya

12/20/23, 1:19 PM

AFAIK the only native control the openssh server gives you is to either completely allow/prohibit port forwarding with the `AllowTcpForwarding` directive but there is nothing to control the number of connections when that is allowed.

Erfan Bahramali

3/27/24, 6:30 PM

https://superuser.com/questions/1764623/limiting-ssh-tunnel-users-maxlogins

Elon Musk

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