Port22/TCP

ssh

Port

Protocol

TCP

What is port 22?

Port 22/TCP is a Well-Known port, assigned by IANA for widely recognized services. It is associated with the ssh service.

The Secure Shell (SSH) Protocol

Useful commands

nmapnmap -p 22 -sV example.com

netcatnc -zv example.com 22

curlcurl -v http://example.com:22/

telnettelnet example.com 22

bash(echo > /dev/tcp/example.com/22) 2>/dev/null

Firewall commands

UFWAllow

sudo ufw allow 22/tcp

Deny

sudo ufw deny 22/tcp

iptablesAllow

sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT

Deny

sudo iptables -D INPUT -p tcp --dport 22 -j ACCEPT

firewalldAllow

sudo firewall-cmd --permanent --add-port=22/tcp

WindowsAllow

netsh advfirewall firewall add rule name="Open Port 22" dir=in action=allow protocol=TCP localport=22

Security Risks

Unauthorized remote access to the server
Brute force attacks against SSH credentials
Exposure of private keys or misconfigurations
Outdated versions with known vulnerabilities

Frequently Asked Questions

What service runs on port 22/TCP?

Port 22/TCP is associated with the ssh service. The Secure Shell (SSH) Protocol

Is it safe to expose port 22 to the Internet?

It depends on the service and configuration. Port 22 (ssh) is a Well-Known port. If you need to expose it, keep the service updated, use strong authentication, and configure a firewall. It's always recommended to restrict access by IP when possible.

How do I check if port 22 is open?

You can use nmap: `nmap -p 22 -sV example.com`, netcat: `nc -zv example.com 22`, or the bash command: `(echo > /dev/tcp/example.com/22) 2>/dev/null && echo "Open" || echo "Closed"`.

How do I open or close port 22 on my firewall?

On Linux with UFW: `sudo ufw allow 22/tcp` (open) or `sudo ufw deny 22/tcp` (close). With iptables: `sudo iptables -A INPUT -p tcp --dport 22 -j ACCEPT`. On Windows: `netsh advfirewall firewall add rule name="Open Port 22" dir=in action=allow protocol=TCP localport=22`.