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// Network services

Port 11877: X2E service discovery protocol

Port 11877 is assigned by IANA to x2e-disc (X2E service discovery protocol).

11877

How x2e-disc works

Network services
client:11877x2e-discresponse client:11877x2e-discresponse

The client sends a request to port 11877 and the x2e-disc 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 11877 dangerous?

We have no specific security note for port 11877. 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 11877

ServicePortTransportDescriptionReferenceUpdated
x2e-disc 11877 UDP X2E service discovery protocol - 2010-09-13
-11877-Reserved--

// source: IANA service name and port number registry

03 Check it

Which program uses port 11877, and is it reachable?

Linux

sudo ss -ltnup 'sport = :11877'      # process listening on 11877
sudo lsof -nP -i :11877

macOS

sudo lsof -nP -i :11877

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 11877 -State Listen | Select LocalAddress, OwningProcess
Get-NetUDPEndpoint -LocalPort 11877
netstat -ano | findstr :11877

From another machine

nmap -p 11877 -sV <host>
sudo nmap -sU -p 11877 <host>
nc -zv <host> 11877

Block it in the firewall

sudo ufw deny 11877/udp                                         # Linux (ufw)
New-NetFirewallRule -DisplayName "Block 11877" -Direction Inbound -LocalPort 11877 -Protocol UDP -Action Block  # Windows
04 FAQ
What is port 11877 used for?

Port 11877 is assigned by IANA to x2e-disc (X2E service discovery protocol).

Is port 11877 TCP or UDP?

Port 11877 is registered for UDP.

Is it safe to open port 11877?

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 11877 is open?

On Linux run "ss -ltnup 'sport = :11877'", on macOS "lsof -nP -i :11877", and on Windows "netstat -ano | findstr :11877" to see the local process. From another machine, "nmap -p 11877 <host>" shows whether it is reachable.

05 Related
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