HTTPfy

Port 505 (mailbox-lm)

IANA assigns port 505 to mailbox-lm.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
mailbox-lm TCP mailbox-lm Beverly Moody -
mailbox-lm UDP mailbox-lm Beverly Moody -

Check what is listening on port 505

Linux: is anything listening on TCP 505?
sudo ss -tlnp 'sport = :505'
Linux: UDP 505
sudo ss -ulnp 'sport = :505'
Linux / macOS: which process owns the port
sudo lsof -nP -i :505
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':505 '
Windows (Command Prompt)
netstat -ano | findstr :505
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 505 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 505
From Windows
Test-NetConnection HOST -Port 505
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 505

Block port 505 in the firewall

ufw
sudo ufw deny 505/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 505 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 505 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 505' -Direction Inbound -Protocol TCP -LocalPort 505 -Action Block
ufw
sudo ufw deny 505/udp
iptables
sudo iptables -A INPUT -p udp --dport 505 -j DROP
nftables
sudo nft add rule inet filter input udp dport 505 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 505' -Direction Inbound -Protocol UDP -LocalPort 505 -Action Block

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Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.