Port 3693 (easl)

IANA assigns port 3693 to easl: Emergency Automatic Structure Lockdown System.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

easl TCP Emergency Automatic Structure Lockdown System
This port was previously removed on 2007-04-05. Mele Associates -

Registry dates for this port: registered 2014-11-26.

Linux: is anything listening on TCP 3693?

sudo ss -tlnp 'sport = :3693'

Linux / macOS: which process owns the port

sudo lsof -nP -i :3693

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':3693 '

Windows (Command Prompt)

netstat -ano | findstr :3693

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 3693 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 3693

From Windows

Test-NetConnection HOST -Port 3693

ufw

sudo ufw deny 3693/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 3693 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 3693 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 3693' -Direction Inbound -Protocol TCP -LocalPort 3693 -Action Block

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