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Port 4342 (lisp-control)

IANA assigns port 4342 to lisp-control: LISP Control Packets.

Registered (user) port, 1024-49151 UDP

Port 4342 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-control UDP LISP Control Packets IETF RFC 9301

Registry dates for this port: registered 2007-05, last modified 2021-02-25.

Check what is listening on port 4342

Linux: UDP 4342
sudo ss -ulnp 'sport = :4342'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4342
Windows (Command Prompt)
netstat -ano | findstr :4342
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 4342

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4342

Block port 4342 in the firewall

ufw
sudo ufw deny 4342/udp
iptables
sudo iptables -A INPUT -p udp --dport 4342 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4342 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4342' -Direction Inbound -Protocol UDP -LocalPort 4342 -Action Block

Related ports

4340gaia4341lisp-data4343unicall4344vinainstall

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