HTTPfy

Port 444 (snpp)

IANA assigns port 444 to snpp: Simple Network Paging Protocol.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
snpp TCP Simple Network Paging Protocol - RFC 1568
snpp UDP Simple Network Paging Protocol - RFC 1568

Check what is listening on port 444

Linux: is anything listening on TCP 444?
sudo ss -tlnp 'sport = :444'
Linux: UDP 444
sudo ss -ulnp 'sport = :444'
Linux / macOS: which process owns the port
sudo lsof -nP -i :444
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':444 '
Windows (Command Prompt)
netstat -ano | findstr :444
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 444 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 444
From Windows
Test-NetConnection HOST -Port 444
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 444

Block port 444 in the firewall

ufw
sudo ufw deny 444/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 444 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 444 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 444' -Direction Inbound -Protocol TCP -LocalPort 444 -Action Block
ufw
sudo ufw deny 444/udp
iptables
sudo iptables -A INPUT -p udp --dport 444 -j DROP
nftables
sudo nft add rule inet filter input udp dport 444 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 444' -Direction Inbound -Protocol UDP -LocalPort 444 -Action Block

Related ports

442cvc-hostd, cvc_hostd443HTTPS445SMB (Microsoft-DS)446ddm-rdb

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