HTTPfy

Port 3909 (surfcontrolcpa)

IANA assigns port 3909 to surfcontrolcpa: SurfControl CPA.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
surfcontrolcpa TCP SurfControl CPA Hywel Morgan -
surfcontrolcpa UDP SurfControl CPA Hywel Morgan -

Registry dates for this port: registered 2003-11.

Check what is listening on port 3909

Linux: is anything listening on TCP 3909?
sudo ss -tlnp 'sport = :3909'
Linux: UDP 3909
sudo ss -ulnp 'sport = :3909'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3909
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3909 '
Windows (Command Prompt)
netstat -ano | findstr :3909
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3909 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3909
From Windows
Test-NetConnection HOST -Port 3909
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3909

Block port 3909 in the firewall

ufw
sudo ufw deny 3909/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3909 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3909 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3909' -Direction Inbound -Protocol TCP -LocalPort 3909 -Action Block
ufw
sudo ufw deny 3909/udp
iptables
sudo iptables -A INPUT -p udp --dport 3909 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3909 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3909' -Direction Inbound -Protocol UDP -LocalPort 3909 -Action Block

Related ports

3907imoguia-port3908hppronetman3910prnrequest3911prnstatus

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