Add a prefix
To add a prefix to Advanced TCP Protection:
Log in to the Cloudflare dashboard and select your account.
Go to Account Home > L3/4 DDoS > Advanced TCP Protection.
Under General settings > Prefixes, select Edit.
Expand the Add existing prefix section and select Add next to the prefix you wish to add.
Alternatively, enter a prefix and (optionally) a description in Prefix and Description, respectively, and select Add.