Port 206 (at-zis)

IANA assigns port 206 to at-zis: AppleTalk Zone Information.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference

at-zis TCP AppleTalk Zone Information - -

at-zis UDP AppleTalk Zone Information - -

Linux: is anything listening on TCP 206?

sudo ss -tlnp 'sport = :206'

Linux: UDP 206

sudo ss -ulnp 'sport = :206'

Linux / macOS: which process owns the port

sudo lsof -nP -i :206

Older Linux / BSD (net-tools)

sudo netstat -tlnp | grep ':206 '

Windows (Command Prompt)

netstat -ano | findstr :206

Windows (PowerShell)

Get-NetTCPConnection -LocalPort 206 -State Listen | Select LocalAddress,OwningProcess

From another machine

nc -vz -w 5 HOST 206

From Windows

Test-NetConnection HOST -Port 206

UDP probe (no reply does not prove it is closed)

nc -vzu -w 5 HOST 206

ufw

sudo ufw deny 206/tcp

iptables

sudo iptables -A INPUT -p tcp --dport 206 -j DROP

nftables

sudo nft add rule inet filter input tcp dport 206 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block TCP 206' -Direction Inbound -Protocol TCP -LocalPort 206 -Action Block

ufw

sudo ufw deny 206/udp

iptables

sudo iptables -A INPUT -p udp --dport 206 -j DROP

nftables

sudo nft add rule inet filter input udp dport 206 drop

Windows Firewall

New-NetFirewallRule -DisplayName 'Block UDP 206' -Direction Inbound -Protocol UDP -LocalPort 206 -Action Block

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