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// Network services

Port 8503: MPLS LSP Self-Ping

Port 8503 is assigned by IANA to lsp-self-ping (MPLS LSP Self-Ping).

8503

How lsp-self-ping works

Network services
client:8503lsp-self-pingresponse client:8503lsp-self-pingresponse

The client sends a request to port 8503 and the lsp-self-ping 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
Network services
01 Security

Is port 8503 dangerous?

We have no specific security note for port 8503. Its risk depends on the program actually listening on it. General advice for network services services:

  • Answer only the networks that need the service (no open resolvers, relays or reflectors).
  • UDP services can be abused for DDoS amplification: rate-limit or block them at the edge.
  • Disable legacy test services that have no use in production.
02 Registry

IANA registry entries for port 8503

ServicePortTransportDescriptionReferenceUpdated
lsp-self-ping 8503 UDP MPLS LSP Self-Ping RFC 7746 2016-02-01
-8503-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 8503, and is it reachable?

Linux

sudo ss -ltnup 'sport = :8503'      # process listening on 8503
sudo lsof -nP -i :8503

macOS

sudo lsof -nP -i :8503

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 8503 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 8503
netstat -ano | findstr :8503

From another machine

nmap -p 8503 -sV <host>
sudo nmap -sU -p 8503 <host>
nc -zv <host> 8503

Block it in the firewall

sudo ufw deny 8503/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 8503" -Direction Inbound -LocalPort 8503 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 8503 used for?

Port 8503 is assigned by IANA to lsp-self-ping (MPLS LSP Self-Ping).

Is port 8503 TCP or UDP?

Port 8503 is registered for UDP.

Is it safe to open port 8503?

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. Answer only the networks that need the service (no open resolvers, relays or reflectors).

How do I check if port 8503 is open?

On Linux run "ss -ltnup 'sport = :8503'", on macOS "lsof -nP -i :8503", and on Windows "netstat -ano | findstr :8503" to see the local process. From another machine, "nmap -p 8503 <host>" shows whether it is reachable.

05 Related
:53 DNS tcp · udp · moderate risk :135 MS RPC tcp · udp · high risk :123 NTP udp · tcp · moderate risk :67 DHCP server udp · tcp · moderate risk :111 rpcbind tcp · udp · high risk :9100 Raw printing (JetDirect) tcp · udp · high risk :631 IPP / CUPS tcp · udp · high risk :5353 mDNS udp · tcp · moderate risk

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