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Port 242 (direct)

IANA assigns port 242 to direct: Direct.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
direct TCP Direct Herb Sutter -
direct UDP Direct Herb Sutter -

Check what is listening on port 242

Linux: is anything listening on TCP 242?
sudo ss -tlnp 'sport = :242'
Linux: UDP 242
sudo ss -ulnp 'sport = :242'
Linux / macOS: which process owns the port
sudo lsof -nP -i :242
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':242 '
Windows (Command Prompt)
netstat -ano | findstr :242
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 242 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 242
From Windows
Test-NetConnection HOST -Port 242
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 242

Block port 242 in the firewall

ufw
sudo ufw deny 242/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 242 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 242 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 242' -Direction Inbound -Protocol TCP -LocalPort 242 -Action Block
ufw
sudo ufw deny 242/udp
iptables
sudo iptables -A INPUT -p udp --dport 242 -j DROP
nftables
sudo nft add rule inet filter input udp dport 242 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 242' -Direction Inbound -Protocol UDP -LocalPort 242 -Action Block

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