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Port 2221 (ethernet-ip-s)

IANA assigns port 2221 to ethernet-ip-s: EtherNet/IP over TLS.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ethernet-ip-s TCP EtherNet/IP over TLS ODVA Inc -
ethernet-ip-s UDP EtherNet/IP over DTLS ODVA Inc -

Registry dates for this port: last modified 2015-05-28.

Check what is listening on port 2221

Linux: is anything listening on TCP 2221?
sudo ss -tlnp 'sport = :2221'
Linux: UDP 2221
sudo ss -ulnp 'sport = :2221'
Linux / macOS: which process owns the port
sudo lsof -nP -i :2221
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':2221 '
Windows (Command Prompt)
netstat -ano | findstr :2221
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 2221 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 2221
From Windows
Test-NetConnection HOST -Port 2221
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 2221

Block port 2221 in the firewall

ufw
sudo ufw deny 2221/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 2221 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 2221 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 2221' -Direction Inbound -Protocol TCP -LocalPort 2221 -Action Block
ufw
sudo ufw deny 2221/udp
iptables
sudo iptables -A INPUT -p udp --dport 2221 -j DROP
nftables
sudo nft add rule inet filter input udp dport 2221 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 2221' -Direction Inbound -Protocol UDP -LocalPort 2221 -Action Block

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