HTTPfy

Port 4546 (sf-lm)

IANA assigns port 4546 to sf-lm: SF License Manager (Sentinel).

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
sf-lm TCP SF License Manager (Sentinel) Thomas Koell -
sf-lm UDP SF License Manager (Sentinel) Thomas Koell -

Check what is listening on port 4546

Linux: is anything listening on TCP 4546?
sudo ss -tlnp 'sport = :4546'
Linux: UDP 4546
sudo ss -ulnp 'sport = :4546'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4546
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4546 '
Windows (Command Prompt)
netstat -ano | findstr :4546
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4546 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4546
From Windows
Test-NetConnection HOST -Port 4546
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4546

Block port 4546 in the firewall

ufw
sudo ufw deny 4546/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4546 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4546 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4546' -Direction Inbound -Protocol TCP -LocalPort 4546 -Action Block
ufw
sudo ufw deny 4546/udp
iptables
sudo iptables -A INPUT -p udp --dport 4546 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4546 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4546' -Direction Inbound -Protocol UDP -LocalPort 4546 -Action Block

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