Alternative SSH port

Some Possible Gotchas

sshd Considerations

• sshd needs to be restarted after edits are made in order to take effect:

# Restart sshd
systemctl restart sshd.service

# Verify that sshd is listening on the port you want
ss -tulpn | grep sshd

• The line in /etc/ssh/sshd_config where the port is configured, is commented out by default. There may also be a ListenAddress directive that is conflicting with your Port directive in /etc/ssh/ssd_config.

# Show relevant lines from your /etc/ssh/sshd_config file
cat /etc/ssh/sshd_config | grep -E '^#?(Port|ListenAddress)' /etc/ssh/sshd_config

Firewall Considerations

• iptables rules are not persistent by default

  • https://www.linode.com/docs/guides/control-network-traffic-with-iptables/#introduction-to-iptables-persistent

• You may be using Cloud Firewalls and are blocking it there

  • https://www.linode.com/docs/guides/getting-started-with-cloud-firewall/

• There may be another rule in your iptables that is overriding the one that you mention:

# Check IP Tables
iptables -L

• There may be a firewall on your local network or computer that is blocking port 47378.

SELinux Considerations

• If you are using SELinux (some RedHat Distributions), you will need to add tcp port 47378 to your port contexts[1][2]:

# Install the tools
dnf update
dnf install policycoreutils-python-utils

# Show current port contexts
semanage port -l | grep ssh

# Update port context
semanage port -a -t ssh_port_t -p tcp 47378

# Verify Changes
semanage port -l | grep ssh

# Open Port on Firewall
firewall-cmd --add-port=47378/tcp --permanent
firewall-cmd --reload

# Restart sshd
systemctl restart sshd

See also

• https://www.linode.com/docs/guides/troubleshooting-ssh/

References:
[1] https://www.cyberciti.biz/faq/howto-change-ssh-port-on-linux-or-unix-server/
[2] https://www.techrepublic.com/article/how-to-configure-ssh-to-use-a-non-standard-port-with-selinux-set-to-enforcing/

I configured SSH to use port 47378 (example).

Did you restart sshd:

sudo systemctl restart sshd

— sw

@stevewi

Yes, I did restart sshd

Thank you for the reply! I'll post an update here after I try everything you mentioned.