We block several outbound ports for network security.
Blocked by default
You may request these blocks be removed by opening a support ticket.
- TCP port 25 (SMTP)
- TCP & UDP port 137 (NetBIOS Name Service)
- TCP & UDP port 138 (NetBIOS Datagram)
- TCP & UDP port 139 (NetBIOS Session)
- TCP & UDP port 445 (SMB over TCP)
- TCP port 1688 (Microsoft Key Management Server, inbound only)
These ports are commonly abused for DDOS attacks. These blocks are permanent and cannot be removed.
- TCP & UDP port 17
- TCP & UDP port 19
- TCP & UDP port 1900
- UDP port 53413
- UDP port 11211
We also filter RFC1918 address ranges on public network interfaces.
- 10.0.0.0 through 10.255.255.255 (10/8 prefix)
- 172.16.0.0 through 172.31.255.255 (172.16/12 prefix)
- 192.168.0.0 through 192.168.255.255 (192.168/16 prefix)