softether VPN client is an open source and free, need to modify :
the application ask for user name and password, must check a WP database if they are valid. ( with API )
then if yes, it download the client vpn files and save it in the local disc, so the user can use to connect to any VPN exist in the list.
the application must download the VPN client files depend on package that the user is subscribed in,
i have 3 packages , every one have specified vpn client files. ( you let me define the server and the directory where the files are located.)
if the user not exist or expired, it ask to login to the site , and renew or register.
the app check in my site if have any updates.
send the user-pass to API in POST or JSON format.
with Basic Auth for security
if ok, valid, not expired, receive full information with expire time.
else receive error message in detail: invalid username or pass, expired....
server error... if could not receive anything
also when valid, the API return link of config file or whole config text in message
so dont need to download... then use this text, save to config file..
app client should have permission for overwritten old config file
( the source code is located here: [url removed, login to view] )