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Port 545 (appleqtcsrvr)

IANA assigns port 545 to appleqtcsrvr.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
appleqtcsrvr TCP appleqtcsrvr Murali Ranganathan -
appleqtcsrvr UDP appleqtcsrvr Murali Ranganathan -

Check what is listening on port 545

Linux: is anything listening on TCP 545?
sudo ss -tlnp 'sport = :545'
Linux: UDP 545
sudo ss -ulnp 'sport = :545'
Linux / macOS: which process owns the port
sudo lsof -nP -i :545
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':545 '
Windows (Command Prompt)
netstat -ano | findstr :545
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 545 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 545
From Windows
Test-NetConnection HOST -Port 545
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 545

Block port 545 in the firewall

ufw
sudo ufw deny 545/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 545 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 545 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 545' -Direction Inbound -Protocol TCP -LocalPort 545 -Action Block
ufw
sudo ufw deny 545/udp
iptables
sudo iptables -A INPUT -p udp --dport 545 -j DROP
nftables
sudo nft add rule inet filter input udp dport 545 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 545' -Direction Inbound -Protocol UDP -LocalPort 545 -Action Block

Related ports

542commerce544kshell546DHCPv6 client547DHCPv6 server

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