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Port 9899 (sctp-tunneling)

IANA assigns port 9899 to sctp-tunneling: SCTP TUNNELING.

Registered (user) port, 1024-49151 UDP

Port 9899 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
sctp-tunneling UDP SCTP TUNNELING IESG RFC 6951

Registry dates for this port: last modified 2013-04-10.

Check what is listening on port 9899

Linux: UDP 9899
sudo ss -ulnp 'sport = :9899'
Linux / macOS: which process owns the port
sudo lsof -nP -i :9899
Windows (Command Prompt)
netstat -ano | findstr :9899
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 9899

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 9899

Block port 9899 in the firewall

ufw
sudo ufw deny 9899/udp
iptables
sudo iptables -A INPUT -p udp --dport 9899 -j DROP
nftables
sudo nft add rule inet filter input udp dport 9899 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 9899' -Direction Inbound -Protocol UDP -LocalPort 9899 -Action Block

Related ports

9889gt-proxy9898monkeycom9900iua9901enrp, enrp-sctp

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