Port 4444: krb524
Port 4444 is officially registered for krb524, a legacy service that translated Kerberos 5 tickets into the older Kerberos 4 format. In practice the number is far better known today as a common default listener port in penetration-testing tools, which is worth knowing if you spot unexpected traffic on it.
| Port number | 4444 |
|---|---|
| Service | Kerberos 5 to 4 ticket translator |
| Protocol | TCP |
| Category | Proxy & tunneling |
| Default encryption | No |
How do I check whether port 4444 is open?
Port 4444 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 4444 | 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 4444 | 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 ':4444 ' | Lists the process bound to port 4444 on Linux. On macOS use lsof -nP -iTCP:4444 -sTCP:LISTEN, on Windows netstat -ano | findstr :4444 |
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 4444 used for?
Port 4444 is officially registered for krb524, a legacy service that translated Kerberos 5 tickets into the older Kerberos 4 format. In practice the number is far better known today as a common default listener port in penetration-testing tools, which is worth knowing if you spot unexpected traffic on it.
Is port 4444 TCP or UDP?
Port 4444 (krb524) uses TCP.
Is port 4444 secure?
Port 4444 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 4444 on my firewall?
Only if you specifically need krb524. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.