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Port 146 (iso-tp0)

IANA assigns port 146 to iso-tp0: ISO-IP0.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
iso-tp0 TCP ISO-IP0 - -
iso-tp0 UDP ISO-IP0 - -

Check what is listening on port 146

Linux: is anything listening on TCP 146?
sudo ss -tlnp 'sport = :146'
Linux: UDP 146
sudo ss -ulnp 'sport = :146'
Linux / macOS: which process owns the port
sudo lsof -nP -i :146
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':146 '
Windows (Command Prompt)
netstat -ano | findstr :146
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 146 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 146
From Windows
Test-NetConnection HOST -Port 146
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 146

Block port 146 in the firewall

ufw
sudo ufw deny 146/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 146 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 146 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 146' -Direction Inbound -Protocol TCP -LocalPort 146 -Action Block
ufw
sudo ufw deny 146/udp
iptables
sudo iptables -A INPUT -p udp --dport 146 -j DROP
nftables
sudo nft add rule inet filter input udp dport 146 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 146' -Direction Inbound -Protocol UDP -LocalPort 146 -Action Block

Related ports

144uma145uaac147iso-ip148jargon

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