![]() ![]() # journalctl _SYSTEMD_UNIT=rvice | grep "Failed"Īfter you’ve identified the IP addresses that frequently hit your SSH server in order to log in to the system with suspicious user accounts or invalid user accounts, you should update your system firewall rules to block the failed SSH attempts IP addresses or use a specialized software, such as fail2ban to manage these attacks. # journalctl _SYSTEMD_UNIT=rvice | grep "failure" In CentOS or RHEL, replace the SSH daemon unit with rvice, as shown in the below command examples. # journalctl _SYSTEMD_UNIT=rvice | egrep "Failed|Failure" #In RHEL, CentOS # journalctl _SYSTEMD_UNIT=ssh.service | egrep "Failed|Failure" In order to display all failed SSH login attempts you should pipe the result via grep filter, as illustrated in the below command examples. On newer Linux distributions you can query the runtime log file maintained by Systemd daemon via journalctl command. # grep "Failed password" /var/log/auth.log | awk ‘’ | uniq -c | sort -nr To display a list of all IP addresses that tried and failed to log in to the SSH server alongside the number of failed attempts of each IP address, issue the below command. # grep "authentication failure" /var/log/secure # egrep "Failed|Failure" /var/log/secureĪ slightly modified version of the above command to display failed SSH logins in CentOS or RHEL is as follows. Issue the above command against this log file to identify failed SSH logins. To display all unsuccessful login attempts, type the lastb command on the terminal without any arguments. ![]() In CentOS or RHEL, the failed SSH sessions are recorded in /var/log/secure file.
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