- 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 517: like tenex link, but across machine - unfortunately, doesn't use link protocol (this is actually just a rendezvous port from which a tcp connection is established)
Port 517 is assigned by IANA to talk (like tenex link, but across machine - unfortunately, doesn't use link protocol (this is actually just a rendezvous port from which a tcp connection is established)).
517
How talk works
Other servicesThe client sends a request to port 517 and the talk 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 517 dangerous?
We have no specific security note for port 517. Its risk depends on the program actually listening on it. General advice for other services services:
IANA registry entries for port 517
| Service | Port | Transport | Description | Reference | Updated |
|---|---|---|---|---|---|
| talk | 517 | TCP, UDP | like tenex link, but across machine - unfortunately, doesn't use link protocol (this is actually just a rendezvous port from which a tcp connection is established) | - | - |
// source: IANA service name and port number registry
Which program uses port 517, and is it reachable?
Linux
sudo ss -ltnup 'sport = :517' # process listening on 517
sudo lsof -nP -i :517macOS
sudo lsof -nP -i :517
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 517 -State Listen | Select LocalAddress, OwningProcess Get-NetUDPEndpoint -LocalPort 517 netstat -ano | findstr :517
From another machine
nmap -p 517 -sV <host> sudo nmap -sU -p 517 <host> nc -zv <host> 517
Block it in the firewall
sudo ufw deny 517/tcp # Linux (ufw) New-NetFirewallRule -DisplayName "Block 517" -Direction Inbound -LocalPort 517 -Protocol TCP -Action Block # Windows
What is port 517 used for?
Port 517 is assigned by IANA to talk (like tenex link, but across machine - unfortunately, doesn't use link protocol (this is actually just a rendezvous port from which a tcp connection is established)).
Is port 517 TCP or UDP?
Port 517 is registered for TCP and UDP.
Is it safe to open port 517?
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 517 is open?
On Linux run "ss -ltnup 'sport = :517'", on macOS "lsof -nP -i :517", and on Windows "netstat -ano | findstr :517" to see the local process. From another machine, "nmap -p 517 <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