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Port 4066 (pmas)

IANA assigns port 4066 to pmas: Performance Measurement and Analysis.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
pmas TCP Performance Measurement and Analysis Zenon Fortuna -
pmas UDP Performance Measurement and Analysis Zenon Fortuna -

Registry dates for this port: registered 2007-02.

Check what is listening on port 4066

Linux: is anything listening on TCP 4066?
sudo ss -tlnp 'sport = :4066'
Linux: UDP 4066
sudo ss -ulnp 'sport = :4066'
Linux / macOS: which process owns the port
sudo lsof -nP -i :4066
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':4066 '
Windows (Command Prompt)
netstat -ano | findstr :4066
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 4066 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 4066
From Windows
Test-NetConnection HOST -Port 4066
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 4066

Block port 4066 in the firewall

ufw
sudo ufw deny 4066/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 4066 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 4066 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 4066' -Direction Inbound -Protocol TCP -LocalPort 4066 -Action Block
ufw
sudo ufw deny 4066/udp
iptables
sudo iptables -A INPUT -p udp --dport 4066 -j DROP
nftables
sudo nft add rule inet filter input udp dport 4066 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 4066' -Direction Inbound -Protocol UDP -LocalPort 4066 -Action Block

Related ports

4064ice-srouter4065avanti-cdp, avanti_cdp4067idp4068ipfltbcst

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