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Port 4333 (ahsp)

IANA assigns port 4333 to ahsp: ArrowHead Service Protocol (AHSP).

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ahsp TCP ArrowHead Service Protocol (AHSP) QuantuMatriX Technologies -
ahsp UDP ArrowHead Service Protocol (AHSP) QuantuMatriX Technologies -
ahsp SCTP ArrowHead Service Protocol (AHSP) QuantuMatriX Technologies -

Registry dates for this port: registered 2014-04-10.

Check what is listening on port 4333

Linux: is anything listening on TCP 4333?
sudo ss -tlnp 'sport = :4333'
Linux: UDP 4333
sudo ss -ulnp 'sport = :4333'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4333
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4333 '
Windows (Command Prompt)
netstat -ano | findstr :4333
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4333 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4333
From Windows
Test-NetConnection HOST -Port 4333
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4333

Block port 4333 in the firewall

ufw
sudo ufw deny 4333/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4333 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4333 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4333' -Direction Inbound -Protocol TCP -LocalPort 4333 -Action Block
ufw
sudo ufw deny 4333/udp
iptables
sudo iptables -A INPUT -p udp --dport 4333 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4333 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4333' -Direction Inbound -Protocol UDP -LocalPort 4333 -Action Block

Related ports

4331ktickets-rest4332getty-focus4334netconf-ch-ssh4335netconf-ch-tls

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