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Port 4341 (lisp-data)

IANA assigns port 4341 to lisp-data: LISP Data Packets.

Registered (user) port, 1024-49151 UDP

Port 4341 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
lisp-data UDP LISP Data Packets IESG RFC 9300

Registry dates for this port: registered 2007-11-12, last modified 2021-02-17.

Check what is listening on port 4341

Linux: UDP 4341
sudo ss -ulnp 'sport = :4341'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4341
Windows (Command Prompt)
netstat -ano | findstr :4341
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4341

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4341

Block port 4341 in the firewall

ufw
sudo ufw deny 4341/udp
iptables
sudo iptables -A INPUT -p udp --dport 4341 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4341 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4341' -Direction Inbound -Protocol UDP -LocalPort 4341 -Action Block

Related ports

4336restconf-ch-tls4340gaia4342lisp-control4343unicall

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.