- Close the port if nothing on the host needs it.
- Identify the process that listens on it (commands below) before opening it in a firewall.
- Expose a service only to the networks that use it.
Port 501: STMF
Port 501 is assigned by IANA to stmf (STMF).
501
How stmf works
Other servicesThe client sends a request to port 501 and the stmf service answers.
- Transport
- TCP · UDP
- Exposure risk
- not rated depends on the program listening
- Encryption
- Unknownnot stated by the registry
- IANA status
- Assigned1 registered service
- Range
- Well-known (0-1023)
- Category
- Other services
Is port 501 dangerous?
We have no specific security note for port 501. Its risk depends on the program actually listening on it. General advice for other services services:
IANA registry entries for port 501
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| stmf | 501 | TCP, UDP | STMF | - | - |
// source: IANA service name and port number registry
Which program uses port 501, and is it reachable?
Linux
sudo ss -ltnup 'sport = :501' # process listening on 501
sudo lsof -nP -i :501macOS
sudo lsof -nP -i :501
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 501 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 501 netstat -ano | findstr :501
From another machine
nmap -p 501 -sV <host> sudo nmap -sU -p 501 <host> nc -zv <host> 501
Block it in the firewall
sudo ufw deny 501/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 501" -Direction Inbound -LocalPort 501 -Protocol TCP -Action Block # Windows
What is port 501 used for?
Port 501 is assigned by IANA to stmf (STMF).
Is port 501 TCP or UDP?
Port 501 is registered for TCP and UDP.
Is it safe to open port 501?
It depends on the program that listens on it. Open it only for a service you know and only to the networks that need it. Close the port if nothing on the host needs it.
How do I check if port 501 is open?
On Linux run "ss -ltnup 'sport = :501'", on macOS "lsof -nP -i :501", and on Windows "netstat -ano | findstr :501" to see the local process. From another machine, "nmap -p 501 <host>" shows whether it is reachable.
Other other services ports
:4444 Metasploit default / krb524 tcp · udp · high risk :31337 Back Orifice / elite tcp · udp · high risk :1 TCP Port Service Multiplexer tcp · udp :5 Remote Job Entry tcp · udp :9 Discard tcp · udp · sctp · dccp :11 Active Users tcp · udp :17 Quote of the Day tcp · udp :18 Message Send Protocol (historic) tcp · udp