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Port 133 (statsrv)

IANA assigns port 133 to statsrv: Statistics Service.

Well-known (system) port, 0-1023 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
statsrv TCP Statistics Service Dave Mills 2 -
statsrv UDP Statistics Service Dave Mills 2 -

Check what is listening on port 133

Linux: is anything listening on TCP 133?
sudo ss -tlnp 'sport = :133'
Linux: UDP 133
sudo ss -ulnp 'sport = :133'
Linux / macOS: which process owns the port
sudo lsof -nP -i :133
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':133 '
Windows (Command Prompt)
netstat -ano | findstr :133
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 133 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 133
From Windows
Test-NetConnection HOST -Port 133
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 133

Block port 133 in the firewall

ufw
sudo ufw deny 133/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 133 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 133 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 133' -Direction Inbound -Protocol TCP -LocalPort 133 -Action Block
ufw
sudo ufw deny 133/udp
iptables
sudo iptables -A INPUT -p udp --dport 133 -j DROP
nftables
sudo nft add rule inet filter input udp dport 133 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 133' -Direction Inbound -Protocol UDP -LocalPort 133 -Action Block

Related ports

131cisco-tna132cisco-sys134ingres-net135Microsoft RPC endpoint mapper

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