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Port 4353 (f5-iquery)

IANA assigns port 4353 to f5-iquery: F5 iQuery.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
f5-iquery TCP F5 iQuery Tom Kee -
f5-iquery UDP F5 iQuery Tom Kee -

Check what is listening on port 4353

Linux: is anything listening on TCP 4353?
sudo ss -tlnp 'sport = :4353'
Linux: UDP 4353
sudo ss -ulnp 'sport = :4353'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4353
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4353 '
Windows (Command Prompt)
netstat -ano | findstr :4353
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4353 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4353
From Windows
Test-NetConnection HOST -Port 4353
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4353

Block port 4353 in the firewall

ufw
sudo ufw deny 4353/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4353 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4353 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4353' -Direction Inbound -Protocol TCP -LocalPort 4353 -Action Block
ufw
sudo ufw deny 4353/udp
iptables
sudo iptables -A INPUT -p udp --dport 4353 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4353 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4353' -Direction Inbound -Protocol UDP -LocalPort 4353 -Action Block

Related ports

4351plcy-net-svcs4352pjlink4354qsnet-trans4355qsnet-workst

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