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Port 169 (send)

IANA assigns port 169 to send: SEND.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
send TCP SEND William Oldwin -
send UDP SEND William Oldwin -

Registry dates for this port: last modified 2019-04-22.

Check what is listening on port 169

Linux: is anything listening on TCP 169?
sudo ss -tlnp 'sport = :169'
Linux: UDP 169
sudo ss -ulnp 'sport = :169'
Linux / macOS: which process owns the port
sudo lsof -nP -i :169
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':169 '
Windows (Command Prompt)
netstat -ano | findstr :169
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 169 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 169
From Windows
Test-NetConnection HOST -Port 169
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 169

Block port 169 in the firewall

ufw
sudo ufw deny 169/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 169 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 169 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 169' -Direction Inbound -Protocol TCP -LocalPort 169 -Action Block
ufw
sudo ufw deny 169/udp
iptables
sudo iptables -A INPUT -p udp --dport 169 -j DROP
nftables
sudo nft add rule inet filter input udp dport 169 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 169' -Direction Inbound -Protocol UDP -LocalPort 169 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.