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Port 5604 (a3-sdunode)

IANA assigns port 5604 to a3-sdunode: A3-SDUNode.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
a3-sdunode TCP A3-SDUNode Mike Dolan -
a3-sdunode UDP A3-SDUNode Mike Dolan -

Check what is listening on port 5604

Linux: is anything listening on TCP 5604?
sudo ss -tlnp 'sport = :5604'
Linux: UDP 5604
sudo ss -ulnp 'sport = :5604'
Linux / macOS: which process owns the port
sudo lsof -nP -i :5604
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':5604 '
Windows (Command Prompt)
netstat -ano | findstr :5604
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 5604 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 5604
From Windows
Test-NetConnection HOST -Port 5604
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 5604

Block port 5604 in the firewall

ufw
sudo ufw deny 5604/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 5604 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 5604 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 5604' -Direction Inbound -Protocol TCP -LocalPort 5604 -Action Block
ufw
sudo ufw deny 5604/udp
iptables
sudo iptables -A INPUT -p udp --dport 5604 -j DROP
nftables
sudo nft add rule inet filter input udp dport 5604 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 5604' -Direction Inbound -Protocol UDP -LocalPort 5604 -Action Block

Related ports

5602a1-msc5603a1-bs5605a4-sdunode5618efr

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