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Port 7784 (s-bfd)

IANA assigns port 7784 to s-bfd: Seamless Bidirectional Forwarding Detection (S-BFD).

Registered (user) port, 1024-49151 UDP

Port 7784 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

IANA assignment

Service nameProtoDescriptionAssigneeReference
s-bfd UDP Seamless Bidirectional Forwarding Detection (S-BFD) IESG RFC 7881

Registry dates for this port: registered 2014-12-24, last modified 2016-07-14.

Check what is listening on port 7784

Linux: UDP 7784
sudo ss -ulnp 'sport = :7784'
Linux / macOS: which process owns the port
sudo lsof -nP -i :7784
Windows (Command Prompt)
netstat -ano | findstr :7784
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 7784

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 7784

Block port 7784 in the firewall

ufw
sudo ufw deny 7784/udp
iptables
sudo iptables -A INPUT -p udp --dport 7784 -j DROP
nftables
sudo nft add rule inet filter input udp dport 7784 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 7784' -Direction Inbound -Protocol UDP -LocalPort 7784 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.