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Port 4739 (ipfix)

IANA assigns port 4739 to ipfix: IP Flow Info Export.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
ipfix TCP IP Flow Info Export Nevil Brownlee -
ipfix UDP IP Flow Info Export Nevil Brownlee -
ipfix SCTP IP Flow Info Export Nevil Brownlee -

Registry dates for this port: registered 2005-08.

Check what is listening on port 4739

Linux: is anything listening on TCP 4739?
sudo ss -tlnp 'sport = :4739'
Linux: UDP 4739
sudo ss -ulnp 'sport = :4739'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4739
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4739 '
Windows (Command Prompt)
netstat -ano | findstr :4739
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4739 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4739
From Windows
Test-NetConnection HOST -Port 4739
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4739

Block port 4739 in the firewall

ufw
sudo ufw deny 4739/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4739 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4739 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4739' -Direction Inbound -Protocol TCP -LocalPort 4739 -Action Block
ufw
sudo ufw deny 4739/udp
iptables
sudo iptables -A INPUT -p udp --dport 4739 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4739 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4739' -Direction Inbound -Protocol UDP -LocalPort 4739 -Action Block

Related ports

4737ipdr-sp4738solera-lpn4740ipfixs4741lumimgrd

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