HTTPfy

Port 3599 (quasar-server)

IANA assigns port 3599 to quasar-server: Quasar Accounting Server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
quasar-server TCP Quasar Accounting Server Brad Pepers -
quasar-server UDP Quasar Accounting Server Brad Pepers -

Registry dates for this port: registered 2002-09.

Check what is listening on port 3599

Linux: is anything listening on TCP 3599?
sudo ss -tlnp 'sport = :3599'
Linux: UDP 3599
sudo ss -ulnp 'sport = :3599'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3599
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3599 '
Windows (Command Prompt)
netstat -ano | findstr :3599
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3599 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3599
From Windows
Test-NetConnection HOST -Port 3599
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3599

Block port 3599 in the firewall

ufw
sudo ufw deny 3599/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3599 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3599 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3599' -Direction Inbound -Protocol TCP -LocalPort 3599 -Action Block
ufw
sudo ufw deny 3599/udp
iptables
sudo iptables -A INPUT -p udp --dport 3599 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3599 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3599' -Direction Inbound -Protocol UDP -LocalPort 3599 -Action Block

Related ports

3597a143598a153600trap-daemon3601visinet-gui

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