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Port 4372 (l2c-data)

IANA assigns port 4372 to l2c-data: LAN2CAN Data.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
l2c-data TCP LAN2CAN Data
Modified: 21 January 2010 Phil Tolson -
l2c-data UDP LAN2CAN Data Phil Tolson -

Registry dates for this port: registered 2008-07-07.

Check what is listening on port 4372

Linux: is anything listening on TCP 4372?
sudo ss -tlnp 'sport = :4372'
Linux: UDP 4372
sudo ss -ulnp 'sport = :4372'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4372
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4372 '
Windows (Command Prompt)
netstat -ano | findstr :4372
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4372 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4372
From Windows
Test-NetConnection HOST -Port 4372
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4372

Block port 4372 in the firewall

ufw
sudo ufw deny 4372/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4372 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4372 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4372' -Direction Inbound -Protocol TCP -LocalPort 4372 -Action Block
ufw
sudo ufw deny 4372/udp
iptables
sudo iptables -A INPUT -p udp --dport 4372 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4372 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4372' -Direction Inbound -Protocol UDP -LocalPort 4372 -Action Block

Related ports

4370elpro-tunnel, elpro_tunnel4371l2c-control, l2c-disc4373remctl4374psi-ptt

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