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Port 284 (corerjd)

IANA assigns port 284 to corerjd.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
corerjd TCP corerjd Chris Thornhill -
corerjd UDP corerjd Chris Thornhill -

Check what is listening on port 284

Linux: is anything listening on TCP 284?
sudo ss -tlnp 'sport = :284'
Linux: UDP 284
sudo ss -ulnp 'sport = :284'
Linux / macOS: which process owns the port
sudo lsof -nP -i :284
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':284 '
Windows (Command Prompt)
netstat -ano | findstr :284
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 284 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 284
From Windows
Test-NetConnection HOST -Port 284
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 284

Block port 284 in the firewall

ufw
sudo ufw deny 284/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 284 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 284 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 284' -Direction Inbound -Protocol TCP -LocalPort 284 -Action Block
ufw
sudo ufw deny 284/udp
iptables
sudo iptables -A INPUT -p udp --dport 284 -j DROP
nftables
sudo nft add rule inet filter input udp dport 284 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 284' -Direction Inbound -Protocol UDP -LocalPort 284 -Action Block

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All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.