Port 31620 (lm-mon)

IANA assigns port 31620 to lm-mon: lm mon.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference

lm-mon TCP lm mon System Administrator -

lm-mon UDP lm mon System Administrator -

Registry dates for this port: registered 2003-06.

Linux: is anything listening on TCP 31620?

sudo ss -tlnp 'sport = :31620'

Linux: UDP 31620

sudo ss -ulnp 'sport = :31620'

Linux / macOS: which process owns the port

sudo lsof -nP -i :31620

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':31620 '

Windows (Command Prompt)

netstat -ano | findstr :31620

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 31620 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 31620

From Windows

Test-NetConnection HOST -Port 31620

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

nc -vzu -w 5 HOST 31620

ufw

sudo ufw deny 31620/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 31620 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 31620 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 31620' -Direction Inbound -Protocol TCP -LocalPort 31620 -Action Block

ufw

sudo ufw deny 31620/udp

iptables

sudo iptables -A INPUT -p udp --dport 31620 -j DROP

nftables

sudo nft add rule inet filter input udp dport 31620 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 31620' -Direction Inbound -Protocol UDP -LocalPort 31620 -Action Block

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