• If CoovaChilli is compiled with JSON support it exposes a JSON interface on the controller.
• This document will discuss the technical workings of the JSON interface.
• In order to have access to the JSON interface you have to be on the same network served by CoovaChilli, this means you have to be connected to the hotspot in plain english.

• The JSON interface is served from the UAMLISTEN IP Address which is typically 10.1.0.1
• It has a standard interface (HTTP) on UAMPORT which is typicallly 3990
• If Coova is configured to also support HTTPS in the UAM, the HTTPS access will be on the UAMUIPORT which is typically port 4990.
• Each of the endpoints can then be reached by appending /json/ and the end point name .
• For HTTP a typical URL will look like this
  • status http://10.1.0.1:3990/json/status
  • logon http://10.1.0.1:3990/json/logon
  • logoff http://10.1.0.1:3990/json/logoff
• For HTTPS a typical URL will look like this
  • status https://10.1.0.1:4990/json/status
  • logon https://10.1.0.1:4990/json/logon
  • logoff https://10.1.0.1:4990/json/logoff

• In order to allow cross site functionality the JSON interface also allows for you to include a value for the callback
• Simply include callback and the required value for it in the query string of the endpoint call.
• http://10.1.0.1:3990/json/status?callback=jQuery33105641008201093548_1612410177983
• The reply will then be wrapped inside the value of callback

jQuery33105641008201093548_1612410177983({"versio......28-D2-44-20-04-8D"}})

• The JSON interface has three endpoints exposed. They are
  • status Report on the current status of the client from which you are making the call
  • logon Used to log a user onto the captive portal. Needs a valid RADIUS username and encrypted password.
  • logoff Used to disconnect a user that has an active session on the captive portal.

We will now unpack each of these endpoints in their own dedicated session

• The reply of a status call will indicate the current connection status of a client / user from where the call was made.
• Here is a typical reply when the user is not connected

{
   "version":"1.0",
   "clientState":0,
   "nasid":"ZA-VM1",
   "challenge":"0caeb2c0240fca8f430ea54e6423151e",
   "location":{"name":"My HotSpot"},
   "redir":{
      "originalURL":"http://detectportal.firefox.com/success.txt",
      "redirectionURL":"",
      "logoutURL":"http://10.1.0.1:3990/logoff",
      "ipAddress":"10.1.0.2",
      "macAddress":"28-D2-44-70-04-00"
    }
}

• Here is a typical reply when the user is connected

{
   "version":"1.0",
   "clientState":1,
   "nasid":"ZA-VM1",
   "redir": {
      "originalURL":"http://detectportal.firefox.com/success.txt",
      "redirectionURL":"",
      "logoutURL":"http://10.1.0.1:3990/logoff",
      "ipAddress":"10.1.0.2",
      "macAddress":"28-D2-44-70-04-00"
   },
   "session":{
      "sessionId":"161241022400000001",
      "userName":"click_to_connect@demo1",
      "startTime":1612410289,
      "sessionTimeout":0,"terminateTime":0,
      "idleTimeout":0,
      "maxTotalOctets":249823541
   },
   "accounting":{
      "sessionTime":15,
      "idleTime":0,
      "inputOctets":144606,
      "outputOctets":85859,
      "inputGigawords":0,
      "outputGigawords":0,
      "viewPoint":"client"
   }
}

• The item that indicates if there is an active session is the value of ClientState
  • 0 No active session
  • 1 Active session

• The logon process consists of three calls
  • Doing a status call to get the latest challenge from the status reply
  • Doing a call the the UAM encryption service on the RADIUSdesk back-end by calling the uam.php script.
  • Using the returned hash value together with the username to to a call to the JSON login end-point.

• Each time we do a call to the status end point we get a new challenge in the reply.
• CoovaChilli remembers the last challenge it generated for a client (when they are not logged in) and uses that during the login process.
• This is why its good practice to do a statuscall as step one of the login process to get a fresh challenge from CoovaChilli. (There is an expiry on the challenge which is why we go this route to ensure we have a current value that hane not expired)
• The call to the status end point was already covered earlier in the document. From it you can see there is a challenge item.