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Port 426 (smartsdp)

IANA assigns port 426 to smartsdp.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
smartsdp TCP smartsdp Marie Pierre Belange -
smartsdp UDP smartsdp Marie Pierre Belange -

Check what is listening on port 426

Linux: is anything listening on TCP 426?
sudo ss -tlnp 'sport = :426'
Linux: UDP 426
sudo ss -ulnp 'sport = :426'
Linux / macOS: which process owns the port
sudo lsof -nP -i :426
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':426 '
Windows (Command Prompt)
netstat -ano | findstr :426
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 426 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 426
From Windows
Test-NetConnection HOST -Port 426
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 426

Block port 426 in the firewall

ufw
sudo ufw deny 426/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 426 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 426 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 426' -Direction Inbound -Protocol TCP -LocalPort 426 -Action Block
ufw
sudo ufw deny 426/udp
iptables
sudo iptables -A INPUT -p udp --dport 426 -j DROP
nftables
sudo nft add rule inet filter input udp dport 426 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 426' -Direction Inbound -Protocol UDP -LocalPort 426 -Action Block

Related ports

424opc-job-track425icad-el427SLP (Service Location Protocol)428ocs-cmu, ocs_cmu

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