Port 113: Ident
Port 113 is the Ident protocol, which some servers, notably IRC networks and older mail servers, query to associate a TCP connection with a username. Most home networks and firewalls can safely reject it.
| Port number | 113 |
|---|---|
| Service | Identification Protocol |
| Protocol | TCP |
| Category | Legacy protocols |
| Default encryption | No |
How do I check whether port 113 is open?
Port 113 carries TCP, so a connection either completes its handshake or it does not, which makes the check definitive.
| Question | Command | What to know |
|---|---|---|
| Is it open on a remote host? | nc -vz example.com 113 | A TCP handshake either completes or it does not, so netcat gives a definitive answer in one line. |
| Same check on Windows | Test-NetConnection example.com -Port 113 | Built into PowerShell. TcpTestSucceeded in the output is the answer; telnet is not installed by default on modern Windows. |
| What is listening locally? | ss -tlnp | grep ':113 ' | Lists the process bound to port 113 on Linux. On macOS use lsof -nP -iTCP:113 -sTCP:LISTEN, on Windows netstat -ano | findstr :113 |
Replace example.com with the host you are testing. A blocked port and a port with nothing listening on it look identical from the outside, so if a service should be running, check locally before blaming the firewall.
Frequently asked questions
What is port 113 used for?
Port 113 is the Ident protocol, which some servers, notably IRC networks and older mail servers, query to associate a TCP connection with a username. Most home networks and firewalls can safely reject it.
Is port 113 TCP or UDP?
Port 113 (Ident) uses TCP.
Is port 113 secure?
Port 113 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 113 on my firewall?
Only if you specifically need Ident. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.