Port 7700 (em7-secom)

IANA assigns port 7700 to em7-secom: EM7 Secure Communications.

Registered (user) port, 1024-49151 TCP

IANA assignment

Service nameProtoDescriptionAssigneeReference

em7-secom TCP EM7 Secure Communications Christopher Cordray -

Registry dates for this port: registered 2008-06-05.

Linux: is anything listening on TCP 7700?

sudo ss -tlnp 'sport = :7700'

Linux / macOS: which process owns the port

sudo lsof -nP -i :7700

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':7700 '

Windows (Command Prompt)

netstat -ano | findstr :7700

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 7700 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 7700

From Windows

Test-NetConnection HOST -Port 7700

ufw

sudo ufw deny 7700/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 7700 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 7700 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 7700' -Direction Inbound -Protocol TCP -LocalPort 7700 -Action Block

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