HTTPfy

Port 15998 (2ping)

IANA assigns port 15998 to 2ping: 2ping Bi-Directional Ping Service.

Registered (user) port, 1024-49151 UDP

Port 15998 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
2ping UDP 2ping Bi-Directional Ping Service Ryan Finnie -

Registry dates for this port: registered 2010-10-06.

Check what is listening on port 15998

Linux: UDP 15998
sudo ss -ulnp 'sport = :15998'
Linux / macOS: which process owns the port
sudo lsof -nP -i :15998
Windows (Command Prompt)
netstat -ano | findstr :15998
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 15998

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 15998

Block port 15998 in the firewall

ufw
sudo ufw deny 15998/udp
iptables
sudo iptables -A INPUT -p udp --dport 15998 -j DROP
nftables
sudo nft add rule inet filter input udp dport 15998 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 15998' -Direction Inbound -Protocol UDP -LocalPort 15998 -Action Block

Related ports

15660bex-xr15740ptp15999programmar16000fmsas

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