Port 802 (mbap-s)

IANA assigns port 802 to mbap-s: Modbus Application Protocol Secure.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference

mbap-s TCP Modbus Application Protocol Secure modbus.org -

mbap-s UDP Modbus Application Protocol Secure modbus.org -

Registry dates for this port: registered 2014-06-10.

Linux: is anything listening on TCP 802?

sudo ss -tlnp 'sport = :802'

Linux: UDP 802

sudo ss -ulnp 'sport = :802'

Linux / macOS: which process owns the port

sudo lsof -nP -i :802

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':802 '

Windows (Command Prompt)

netstat -ano | findstr :802

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 802 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 802

From Windows

Test-NetConnection HOST -Port 802

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 802

ufw

sudo ufw deny 802/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 802 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 802 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 802' -Direction Inbound -Protocol TCP -LocalPort 802 -Action Block

ufw

sudo ufw deny 802/udp

iptables

sudo iptables -A INPUT -p udp --dport 802 -j DROP

nftables

sudo nft add rule inet filter input udp dport 802 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 802' -Direction Inbound -Protocol UDP -LocalPort 802 -Action Block

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