Port 742 (netrcs)

IANA assigns port 742 to netrcs: Network based Rev. Cont. Sys..

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

IANA assignment

Service nameProtoDescriptionAssigneeReference

netrcs TCP Network based Rev. Cont. Sys. Gordon C Galligher -

netrcs UDP Network based Rev. Cont. Sys. Gordon C Galligher -

Linux: is anything listening on TCP 742?

sudo ss -tlnp 'sport = :742'

Linux: UDP 742

sudo ss -ulnp 'sport = :742'

Linux / macOS: which process owns the port

sudo lsof -nP -i :742

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':742 '

Windows (Command Prompt)

netstat -ano | findstr :742

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 742 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 742

From Windows

Test-NetConnection HOST -Port 742

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

nc -vzu -w 5 HOST 742

ufw

sudo ufw deny 742/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 742 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 742 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 742' -Direction Inbound -Protocol TCP -LocalPort 742 -Action Block

ufw

sudo ufw deny 742/udp

iptables

sudo iptables -A INPUT -p udp --dport 742 -j DROP

nftables

sudo nft add rule inet filter input udp dport 742 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 742' -Direction Inbound -Protocol UDP -LocalPort 742 -Action Block

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