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Port 8125 (StatsD)

StatsD metrics (Datadog agent DogStatsD, Telegraf, statsd_exporter).

Registered (user) port, 1024-49151 UDP Monitoring and logging Localhost or LAN only

Port 8125 is normally used over UDP; the checker tests TCP only, so a "filtered" result does not mean the UDP service is down.

What port 8125 is used for

StatsD metrics (Datadog agent DogStatsD, Telegraf, statsd_exporter).

Security: should port 8125 be open?

Localhost or LAN only. UDP and unauthenticated; listen on localhost or the pod network only.

IANA assignment

Port 8125 is in the registered range and has no IANA assignment. The usage above is unofficial but widespread.

Check what is listening on port 8125

Linux: UDP 8125
sudo ss -ulnp 'sport = :8125'
Linux / macOS: which process owns the port
sudo lsof -nP -i :8125
Windows (Command Prompt)
netstat -ano | findstr :8125
Windows (PowerShell)
Get-NetUDPEndpoint -LocalPort 8125

Test it from outside

UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 8125

Block port 8125 in the firewall

ufw
sudo ufw deny 8125/udp
iptables
sudo iptables -A INPUT -p udp --dport 8125 -j DROP
nftables
sudo nft add rule inet filter input udp dport 8125 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 8125' -Direction Inbound -Protocol UDP -LocalPort 8125 -Action Block

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