Port 11877 (x2e-disc)

IANA assigns port 11877 to x2e-disc: X2E service discovery protocol.

Registered (user) port, 1024-49151 UDP

Port 11877 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference

x2e-disc UDP X2E service discovery protocol Hannes K -

Registry dates for this port: registered 2010-09-13.

Linux: UDP 11877

sudo ss -ulnp 'sport = :11877'

Linux / macOS: which process owns the port

sudo lsof -nP -i :11877

Windows (Command Prompt)

netstat -ano | findstr :11877

Windows (PowerShell)

Get-NetUDPEndpoint -LocalPort 11877

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 11877

ufw

sudo ufw deny 11877/udp

iptables

sudo iptables -A INPUT -p udp --dport 11877 -j DROP

nftables

sudo nft add rule inet filter input udp dport 11877 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 11877' -Direction Inbound -Protocol UDP -LocalPort 11877 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.