HTTPfy

Port 3951 (pwgippfax)

IANA assigns port 3951 to pwgippfax: PWG IPP Facsimile.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
pwgippfax TCP PWG IPP Facsimile Ira McDonald -
pwgippfax UDP PWG IPP Facsimile Ira McDonald -

Registry dates for this port: registered 2004-08.

Check what is listening on port 3951

Linux: is anything listening on TCP 3951?
sudo ss -tlnp 'sport = :3951'
Linux: UDP 3951
sudo ss -ulnp 'sport = :3951'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3951
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3951 '
Windows (Command Prompt)
netstat -ano | findstr :3951
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3951 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3951
From Windows
Test-NetConnection HOST -Port 3951
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 3951

Block port 3951 in the firewall

ufw
sudo ufw deny 3951/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3951 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3951 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3951' -Direction Inbound -Protocol TCP -LocalPort 3951 -Action Block
ufw
sudo ufw deny 3951/udp
iptables
sudo iptables -A INPUT -p udp --dport 3951 -j DROP
nftables
sudo nft add rule inet filter input udp dport 3951 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 3951' -Direction Inbound -Protocol UDP -LocalPort 3951 -Action Block

Related ports

3949drip3950namemunge3952i3-sessionmgr3953xmlink-connect

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