What Ports Are Blocked?

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
TCP & UDP port 138
TCP & UDP port 139
TCP & UDP port 445
TCP port 1688 (KMS, inbound only)

Permanently blocked

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 addresses on public NICs.

10.0.0.0        -   10.255.255.255  (10/8 prefix)
172.16.0.0      -   172.31.255.255  (172.16/12 prefix)
192.168.0.0     -   192.168.255.255 (192.168/16 prefix)