CentOS Linux 5/6: Change OpenSSH Port Number

I

am a new CentOS Linux user. How do I change default sshd tcp port # 22 to 2022 on CentOS Linux version 5/6?

 

You can set or specifies the port number that sshd server listens on. The default is TCP port # 22.

Syntax: Change SSH port on a CentOS Linux

You can use any one of the following option in /etc/ssh/sshd_config file:

Port PortNumberHere

OR

ListenAddress IPv4Address:Port

ListenAddress IPv6Address:Port

ListenAddress Hostname:Port

If Port is not specified, sshd will listen on the address and all prior Port options specified. The default is to listen on all local IP addresses. Multiple ListenAddress options are aloowed in sshd_config.

Run ssh on a non-standard port # 2022 using Port option

Edit /etc/ssh/sshd_config, enter:

# vi /etc/ssh/sshd_config

 

Edit/Append as follows to set Port to 2022:

Port 2022

 

Save and close the file.

CentOS run ssh on a non-standard port # 2022 using ListenAddress option

Note: If you have multiple IP address on the server, try ListenAddress as follows :

bind sshd to two ip address on a non-standard port ##

ListenAddress 192.168.1.5:2022

ListenAddress 203.1.2.3:2022

Save and close the file.

Reload SSHD service

Before you restart or reload sshd server. You need to update:

SELinux configuration

Firewall settings

fail2ban settings

A note about OpenSSH SELinux user

If you are using SELinux, add tcp port # 2022 to port contexts for OpenSSH server:

# semanage port -a -t ssh_port_t -p tcp 2022

Update firewall settings

You also need to update firewall settings so that users can login using TCP # 2022. Edit, /etc/sysconfig/iptables and open sshd port 2022:

# vi /etc/sysconfig/iptables

 

Edit/append as follows:

delete or comment out port 22 line ##

-A INPUT -m state –state NEW -m tcp -p tcp –dport 22 -j ACCEPT

open port 2022

-A INPUT -m state –state NEW -m tcp -p tcp –dport 2022 -j ACCEPT

Save and close the file. If you are using IPv6, edit /etc/sysconfig/ip6tables file too. Temporally, stop the firewall so that you will not loos the connectivity to the server:

# service iptables stop

# service ip6tables stop

Fail2ban settings

Fail2ban scans log files and bans IPs that show the malicious signs — too many password failures, seeking for exploits, ssh login etc. See this comment below on how to change your port number and you use fail2ban you have to update the rules.

Restart sshd on a CentOS

Type the following command to restart / reload SSHD service:

# service sshd reload

Verify new port settings with the following netstat command:

# netstat -tulpn | grep sshd

Finally, star the firewall on a CentOS Linux:

# service iptables start

IPv6 ##

# service ip6tables start

How do I connect to ssh server on port # 2022 using ssh command?

The syntax is:

ssh -p PortNumberHere user@server-name-here

ssh -p PortNumberHere user@server-name-here commandNameHere

ssh -p 2022 nixcraft@192.168.1.5

ssh -p 2022 nixcraft@192.168.1.5 df

How do I connect to ssh server on port # 2022 using scp command?

The syntax is:

scp -P PortNumberHere source user@server-name-here:/path/to/dest

scp -P 2022 resume.pdf nixcraft@nas01:/backups/personal/nixcraft/files/

How do I connect to ssh server on port # 2022 using sftp command?

The syntax is:

sftp -P PortNumberHere user@server-name-here

sftp -P 2022 nixcraft@192.168.1.5

How do I connect to ssh server on port # 2022 using rsync command?

The syntax is as follows to change SSH port number with rsync command:

sync -av -e  ssh -p PORT-NUMBER-HERE  source user@server-name

So to backup /home/vivek to server1.nixcraft.net.in at port number 2022, enter:

rsync -av -e  ssh -p 2022  /home/vivek/ backupop@server1.nixcraft.net.in

I also suggest that you can update your /.ssh/config ($HOME/.ssh/config) fileto overrides the Port settings. This will save you some time whenever you use ssh/scp/sftp command.

See also

RHEL/Red Hat Change SSH Port

Man pages: sshd(8),sshd_config(5)

 

 

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