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Port 1659 (sg-lm)

IANA assigns port 1659 to sg-lm: Silicon Grail License Manager.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
sg-lm TCP Silicon Grail License Manager William R Bishop -
sg-lm UDP Silicon Grail License Manager William R Bishop -

Check what is listening on port 1659

Linux: is anything listening on TCP 1659?
sudo ss -tlnp 'sport = :1659'
Linux: UDP 1659
sudo ss -ulnp 'sport = :1659'
Linux / macOS: which process owns the port
sudo lsof -nP -i :1659
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':1659 '
Windows (Command Prompt)
netstat -ano | findstr :1659
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 1659 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 1659
From Windows
Test-NetConnection HOST -Port 1659
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 1659

Block port 1659 in the firewall

ufw
sudo ufw deny 1659/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 1659 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 1659 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 1659' -Direction Inbound -Protocol TCP -LocalPort 1659 -Action Block
ufw
sudo ufw deny 1659/udp
iptables
sudo iptables -A INPUT -p udp --dport 1659 -j DROP
nftables
sudo nft add rule inet filter input udp dport 1659 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 1659' -Direction Inbound -Protocol UDP -LocalPort 1659 -Action Block

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