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// Other services

Port 6635: Encapsulate MPLS packets in UDP tunnels.

Port 6635 is assigned by IANA to mpls-udp (Encapsulate MPLS packets in UDP tunnels.).

6635

How mpls-udp works

Other services
client:6635mpls-udpresponse client:6635mpls-udpresponse

The client sends a request to port 6635 and the mpls-udp service answers.

Transport
UDP
Exposure risk
not rated depends on the program listening
Encryption
Unknownnot stated by the registry
IANA status
Assigned1 registered service
Range
Registered (1024-49151)
Category
Other services
01 Security

Is port 6635 dangerous?

We have no specific security note for port 6635. Its risk depends on the program actually listening on it. General advice for other services services:

  • 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.
02 Registry

IANA registry entries for port 6635

ServicePortTransportDescriptionReferenceUpdated
mpls-udp 6635 UDP Encapsulate MPLS packets in UDP tunnels. RFC 7510 2015-02-10
-6635-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 6635, and is it reachable?

Linux

sudo ss -ltnup 'sport = :6635'      # process listening on 6635
sudo lsof -nP -i :6635

macOS

sudo lsof -nP -i :6635

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6635 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 6635
netstat -ano | findstr :6635

From another machine

nmap -p 6635 -sV <host>
sudo nmap -sU -p 6635 <host>
nc -zv <host> 6635

Block it in the firewall

sudo ufw deny 6635/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 6635" -Direction Inbound -LocalPort 6635 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 6635 used for?

Port 6635 is assigned by IANA to mpls-udp (Encapsulate MPLS packets in UDP tunnels.).

Is port 6635 TCP or UDP?

Port 6635 is registered for UDP.

Is it safe to open port 6635?

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 6635 is open?

On Linux run "ss -ltnup 'sport = :6635'", on macOS "lsof -nP -i :6635", and on Windows "netstat -ano | findstr :6635" to see the local process. From another machine, "nmap -p 6635 <host>" shows whether it is reachable.

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