Port 515: LPD
Port 515 is the Line Printer Daemon protocol, the classic Unix printing system that queues and forwards print jobs to a printer or print server. It has mostly been replaced by IPP on port 631, but many printers still accept LPD for compatibility.
| Port number | 515 |
|---|---|
| Service | Line Printer Daemon |
| Protocol | TCP |
| Category | Printing |
| Default encryption | No |
How do I check whether port 515 is open?
Port 515 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 515 | 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 515 | 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 ':515 ' | Lists the process bound to port 515 on Linux. On macOS use lsof -nP -iTCP:515 -sTCP:LISTEN, on Windows netstat -ano | findstr :515 |
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 515 used for?
Port 515 is the Line Printer Daemon protocol, the classic Unix printing system that queues and forwards print jobs to a printer or print server. It has mostly been replaced by IPP on port 631, but many printers still accept LPD for compatibility.
Is port 515 TCP or UDP?
Port 515 (LPD) uses TCP.
Is port 515 secure?
Port 515 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 515 on my firewall?
Only if you specifically need LPD. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.