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Port 1421 (gandalf-lm)

IANA assigns port 1421 to gandalf-lm: Gandalf License Manager.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
gandalf-lm TCP Gandalf License Manager gilmer -
gandalf-lm UDP Gandalf License Manager gilmer -

Check what is listening on port 1421

Linux: is anything listening on TCP 1421?
sudo ss -tlnp 'sport = :1421'
Linux: UDP 1421
sudo ss -ulnp 'sport = :1421'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1421
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1421 '
Windows (Command Prompt)
netstat -ano | findstr :1421
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1421 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1421
From Windows
Test-NetConnection HOST -Port 1421
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1421

Block port 1421 in the firewall

ufw
sudo ufw deny 1421/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1421 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1421 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1421' -Direction Inbound -Protocol TCP -LocalPort 1421 -Action Block
ufw
sudo ufw deny 1421/udp
iptables
sudo iptables -A INPUT -p udp --dport 1421 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1421 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1421' -Direction Inbound -Protocol UDP -LocalPort 1421 -Action Block

Related ports

1419timbuktu-srv31420timbuktu-srv41422autodesk-lm1423essbase

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