Port 22 SSH
Port 22 is the IANA-assigned ssh port for The Secure Shell (SSH) Protocol (TCP / UDP / SCTP).
What is port 22 used for?
Port 22 is assigned to ssh and uses TCP / UDP / SCTP. The IANA registry describes the service as “The Secure Shell (SSH) Protocol”. It sits in the well-known range, which operating systems reserve for core network services, so software expects it at this number by default.
Ports are the transport-layer address a service listens on. A client that wants to reach ssh connects to port 22. A TCP connection is refused when nothing is listening, while a UDP request simply goes unanswered. That is why a port conflict appears whenever two processes try to bind the same number.
Use the commands below to confirm whether port 22 is actually in use before you change firewall rules. Blocking the port stops new inbound traffic at the firewall, but it does not stop a local process from listening, and it does not remove the service from the machine.
Browse all Remote access ports
Source: IANA Service Name and Transport Protocol Port Number Registry. Registered assignee: [Randall_Stewart]. Reference: [RFC 4251].
Check and block port 22
Copy-ready commands for the protocols assigned to this port. Run the check first, then block only what should not be reachable.
Check on Linux
sudo ss -tlpn 'sport = :22'
sudo ss -ulpn 'sport = :22'
sudo ss -Slpn 'sport = :22'Check on Windows
Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue
Get-NetUDPEndpoint -LocalPort 22 -ErrorAction SilentlyContinueBlock with UFW
sudo ufw deny 22/tcp
sudo ufw deny 22/udpBlock with iptables
sudo iptables -A INPUT -p tcp --dport 22 -j DROP
sudo iptables -A INPUT -p udp --dport 22 -j DROP
sudo iptables -A INPUT -p sctp --dport 22 -j DROPThese commands are examples for a typical host. Check the listener before you change firewall rules, and persist iptables rules with iptables-save or netfilter-persistent. On Windows, use Windows Defender Firewall or New-NetFirewallRule for persistent blocks. The iptables rules here cover IPv4; mirror them with ip6tables if IPv6 is enabled. UFW and the built-in Windows cmdlets cover TCP and UDP only; this port also lists SCTP, so use nftables, iptables or the vendor's diagnostic tool for those protocols. SCTP and DCCP handling also depends on kernel support, including their diagnostic modules, so a missing result may mean the module is not loaded rather than that nothing is listening.
Is port 22 safe to expose?
SSH is encrypted but constantly targeted by credential-stuffing bots; use keys, disable password login and consider fail2ban. Expose this port only when the service is actually needed. Keep it patched, prefer an encrypted alternative, and limit source addresses with a firewall allowlist.
Where port 22 is usually used
Most traffic on port 22 falls into these scenarios. The demo below is a safe way to confirm the listener before you change anything.
- Administrators connecting through a bastion host or VPN to manage a machine.
- Automation and CI jobs opening short-lived sessions to run commands.
- Port forwarding that keeps an internal service off the public network.
Open an SSH session
Use a key-based login where possible. Replace the user and host with your own bastion target.
ssh -p 22 user@server.example.comCommon problems with port 22
Connection refused or timed out
Refused usually means the host is reachable but nothing is listening on port 22. A timeout more often means a firewall drop, a wrong host or a service bound to a different interface.
Port already in use
Find the process holding the port with sudo ss -tlpn 'sport = :22' or sudo lsof -i :22. Stop that process or configure it to bind another port; killing it without identifying it can take down a production service.
Firewall rule did not survive a reboot
UFW and Windows Firewall keep rules across restarts. Raw iptables rules do not: save them with iptables-save or the netfilter-persistent package, and re-apply after upgrades that reset the ruleset.
The port is blocked but still reachable
A firewall rule filters inbound traffic; it does not close the listener. Confirm with the check command above and bind the service to 127.0.0.1 when only local clients need it.
Port 22 at a glance
| Port number | 22 |
|---|---|
| Service name | ssh |
| Transport protocol | TCP / UDP / SCTP |
| Category | Remote access |
| Range | Well-known port (0–1023) |
| Risk level | Medium |
| Registered assignee | [Randall_Stewart] |
| Reference | [RFC 4251] |
| Registry description | The Secure Shell (SSH) Protocol |
| Source | IANA Service Name and Transport Protocol Port Number Registry |
Frequently asked questions
What is port 22 used for?
Port 22 (SSH) uses TCP / UDP / SCTP. The Secure Shell (SSH) Protocol.
How do I check if port 22 is open?
On Linux run `sudo ss -tlpn 'sport = :22'` and `sudo ss -ulpn 'sport = :22'` and `sudo ss -Slpn 'sport = :22'`. On Windows run `Get-NetTCPConnection -LocalPort 22 -State Listen -ErrorAction SilentlyContinue` and `Get-NetUDPEndpoint -LocalPort 22 -ErrorAction SilentlyContinue` in PowerShell. If the port is open, the output shows a process listening on port 22; empty output usually means nothing is bound to it. UFW and the built-in Windows cmdlets cover TCP and UDP only; SCTP needs nftables, iptables or the vendor's diagnostic tool.
How do I block port 22?
With UFW run `sudo ufw deny 22/tcp` and `sudo ufw deny 22/udp`. With iptables run `sudo iptables -A INPUT -p tcp --dport 22 -j DROP` and `sudo iptables -A INPUT -p udp --dport 22 -j DROP` and `sudo iptables -A INPUT -p sctp --dport 22 -j DROP`. Persist the iptables rules with your distribution's netfilter-persistent or iptables-save tooling so they survive a reboot. UFW covers TCP and UDP only; use iptables or nftables for SCTP.
Is port 22 safe to expose?
SSH is encrypted but constantly targeted by credential-stuffing bots; use keys, disable password login and consider fail2ban. Nevertheless, expose this port only when the service is actually needed. Keep it patched, prefer an encrypted alternative, and limit source addresses with a firewall allowlist.
Related ports
Primary data: IANA Service Name and Transport Protocol Port Number Registry.
Last reviewed 2026-10-30 · Methodology · About · Privacy