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Port 4047 (ctp-state)

IANA assigns port 4047 to ctp-state: Context Transfer Protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ctp-state TCP Context Transfer Protocol Hesham Soliman -
ctp-state UDP Context Transfer Protocol Hesham Soliman -

Registry dates for this port: registered 2005-11.

Check what is listening on port 4047

Linux: is anything listening on TCP 4047?
sudo ss -tlnp 'sport = :4047'
Linux: UDP 4047
sudo ss -ulnp 'sport = :4047'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4047
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4047 '
Windows (Command Prompt)
netstat -ano | findstr :4047
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4047 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4047
From Windows
Test-NetConnection HOST -Port 4047
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4047

Block port 4047 in the firewall

ufw
sudo ufw deny 4047/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4047 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4047 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4047' -Direction Inbound -Protocol TCP -LocalPort 4047 -Action Block
ufw
sudo ufw deny 4047/udp
iptables
sudo iptables -A INPUT -p udp --dport 4047 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4047 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4047' -Direction Inbound -Protocol UDP -LocalPort 4047 -Action Block

Related ports

4045npp4046acp-proto4049wafs4050cisco-wafs

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