How to limit the number of SSH logins in Centos

Centos how to limit the number of SSH login, I believe that many inexperienced people do not know what to do, so this article summarizes the causes of the problem and solutions, through this article I hope you can solve this problem.

The first method: verified.

1.ssh timeout setting

# cd / etc/profile.d/ # create two blank files autologout.csh and autologout.sh to save the TMOUT configuration

# touch autologout.csh

# touch autologout.sh

# vi autologout.sh # Editing autologout.sh

# auto out in 5 minutes

TMOUT=300 # timeout in s

Readonly TMOUT # set the TMOUT variable read-only

Export TMOUT # set environment TMOUT

# vi autologout.csh # Editing autologout.csh

Set-r autologout 2

# chmod + x autologout.* # executable permissions, in fact, just give Ubunx.

Disconnect Client, log in to the terminal again for 5 minutes without using ssh will automatically disconnect.

2. Limit the number of ssh authentication:

/ etc/ssh/sshd_config

MaxAuthTries=3 this is only more than 3 validation errors disconnecting.

The second method: (there are still problems in the experiment)

Principle: realized through the pam authentication of the system.

1. Backup / etc/pam.d/system_auth file, change:

#% PAM-1.0

# This file is auto-generated.

# User changes will be destroyed the next time authconfig is run.

Auth required pam_env.so

Auth required pam_unix.so nullok try_first_pass changed the original sufficient to required

# auth requisite pam_succeed_if.so uid > = 500quiet comment out this line

Add one line to auth required pam_tally.so deny=3unlock_time=300 and log in after 5 minutes after 3 failures.

# auth required pam_deny.so comment out this line

Account required pam_unix.so

Account sufficient pam_succeed_if.so uid