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Port 603 (idxp)

IANA assigns port 603 to idxp: IDXP.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
idxp TCP IDXP - RFC 4767
idxp UDP IDXP - RFC 4767

Check what is listening on port 603

Linux: is anything listening on TCP 603?
sudo ss -tlnp 'sport = :603'
Linux: UDP 603
sudo ss -ulnp 'sport = :603'
Linux / macOS: which process owns the port
sudo lsof -nP -i :603
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':603 '
Windows (Command Prompt)
netstat -ano | findstr :603
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 603 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 603
From Windows
Test-NetConnection HOST -Port 603
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 603

Block port 603 in the firewall

ufw
sudo ufw deny 603/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 603 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 603 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 603' -Direction Inbound -Protocol TCP -LocalPort 603 -Action Block
ufw
sudo ufw deny 603/udp
iptables
sudo iptables -A INPUT -p udp --dport 603 -j DROP
nftables
sudo nft add rule inet filter input udp dport 603 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 603' -Direction Inbound -Protocol UDP -LocalPort 603 -Action Block

Related ports

601Syslog (reliable, TCP)602xmlrpc-beep604tunnel605soap-beep

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