Port 6704 (frc-hp)

IANA assigns port 6704 to frc-hp: ForCES HP (High Priority) channel.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

frc-hp SCTP ForCES HP (High Priority) channel - RFC 5811

Linux: is anything listening on TCP 6704?

sudo ss -tlnp 'sport = :6704'

Linux / macOS: which process owns the port

sudo lsof -nP -i :6704

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':6704 '

Windows (Command Prompt)

netstat -ano | findstr :6704

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 6704 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 6704

From Windows

Test-NetConnection HOST -Port 6704

ufw

sudo ufw deny 6704/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 6704 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 6704 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 6704' -Direction Inbound -Protocol TCP -LocalPort 6704 -Action Block

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