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Asked: 2020-04-25 03:31:07 +0800 CST

Is it possible to limit OpenSSH maximum number of clients?

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I am trying to limit the number of total OpenSSH connections to our Unix systems.

At first, I have tried modifying OpenSSH configuration with MaxSessions and MaxStartups options but with no success. They are ignored (maybe I don't really understand what this options are intended to).

Using PAM limits in /etc/security/limits.conf I have succeed with maxsyslogins directive:

# limit connections to the system to 10
*    -    maxsyslogins    10

It works, but we are limiting all kind of logins to the system, and using a third party solution to apply limitations to OpenSSH. By example, we have different kind of Unix (HP-UX, Solaris, Linux, AIX) and in not every server we are using PAM for authentication.

I mean, does it exists a simpler and more direct way to do it? Something similar to Apache MaxClients directive?

I don't find it and it's very strange for me that OpenSSH does not have this possibility :-|.

ssh limits

1 Answers

  1. Suppose you want maximum 20 connections, you could remove all pty[c-z]? files from /dev, leaving only ptya[0-9] and ptyb[0-9].

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