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Port 9400 (sec-t4net-srv)

IANA assigns port 9400 to sec-t4net-srv: Samsung Twain for Network Server.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
sec-t4net-srv TCP Samsung Twain for Network Server Dongkeun Kim -
sec-t4net-srv UDP Samsung Twain for Network Server Dongkeun Kim -

Registry dates for this port: registered 2007-02.

Check what is listening on port 9400

Linux: is anything listening on TCP 9400?
sudo ss -tlnp 'sport = :9400'
Linux: UDP 9400
sudo ss -ulnp 'sport = :9400'
Linux / macOS: which process owns the port
sudo lsof -nP -i :9400
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':9400 '
Windows (Command Prompt)
netstat -ano | findstr :9400
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 9400 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 9400
From Windows
Test-NetConnection HOST -Port 9400
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 9400

Block port 9400 in the firewall

ufw
sudo ufw deny 9400/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 9400 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 9400 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 9400' -Direction Inbound -Protocol TCP -LocalPort 9400 -Action Block
ufw
sudo ufw deny 9400/udp
iptables
sudo iptables -A INPUT -p udp --dport 9400 -j DROP
nftables
sudo nft add rule inet filter input udp dport 9400 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 9400' -Direction Inbound -Protocol UDP -LocalPort 9400 -Action Block

Related ports

9396fjinvmgr9397mpidcagt9401sec-t4net-clt9402sec-pc2fax-srv

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