HTTPfy

Port 507 (crs)

IANA assigns port 507 to crs.

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

IANA assignment

Service nameProtoDescriptionAssigneeReference
crs TCP crs Brad Wright -
crs UDP crs Brad Wright -

Check what is listening on port 507

Linux: is anything listening on TCP 507?
sudo ss -tlnp 'sport = :507'
Linux: UDP 507
sudo ss -ulnp 'sport = :507'
Linux / macOS: which process owns the port
sudo lsof -nP -i :507
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':507 '
Windows (Command Prompt)
netstat -ano | findstr :507
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 507 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 507
From Windows
Test-NetConnection HOST -Port 507
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 507

Block port 507 in the firewall

ufw
sudo ufw deny 507/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 507 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 507 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 507' -Direction Inbound -Protocol TCP -LocalPort 507 -Action Block
ufw
sudo ufw deny 507/udp
iptables
sudo iptables -A INPUT -p udp --dport 507 -j DROP
nftables
sudo nft add rule inet filter input udp dport 507 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 507' -Direction Inbound -Protocol UDP -LocalPort 507 -Action Block

Related ports

505mailbox-lm506ohimsrv508xvttp509snare

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