HTTPfy

Port 3100 (Grafana Loki)

Loki log aggregation HTTP API (push and query).

Registered (user) port, 1024-49151 TCP Monitoring and logging Do not expose to the internet

What port 3100 is used for

Loki log aggregation HTTP API (push and query).

Security: should port 3100 be open?

Do not expose to the internet. Loki has no auth of its own; put it behind a gateway with authentication.

IANA assignment

Service nameProtoDescriptionAssigneeReference
opcon-xps TCP OpCon/xps David Bourland -
opcon-xps UDP OpCon/xps David Bourland -

Check what is listening on port 3100

Linux: is anything listening on TCP 3100?
sudo ss -tlnp 'sport = :3100'
Linux / macOS: which process owns the port
sudo lsof -nP -i :3100
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':3100 '
Windows (Command Prompt)
netstat -ano | findstr :3100
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 3100 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 3100
From Windows
Test-NetConnection HOST -Port 3100

Block port 3100 in the firewall

ufw
sudo ufw deny 3100/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 3100 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 3100 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 3100' -Direction Inbound -Protocol TCP -LocalPort 3100 -Action Block

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