Chrome External Protocol Handler Not Working. Apps Not Launching Automatically, Instead it Downloads ICA Files

Chrome External Protocol handler not working. Apps not launching automatically, instead it downloads ICA files.

Issue happens to every machine going to the same NetScaler Gateway.

NetScaler was not able to resolve the StoreFront FQDN. The Name Server was replying, however the response was truncated because it was too large for UDP. To resolve this issue change the Name server to TCP_UDP. NetScaler will now be able to validate the STA ticket with StoreFront server. This is necessary for External Protocol handler and webhelper to work properly.

With Google chrome NPAPI protocol disabled, StoreFront 3.0+ now supports External Protocol handler with latest Receiver 4.3.100.10+.

How external Protocol Handler Works?

From Client to StoreFront or StoreFront LB:
1.- User browses to Storefront URL (Site Needs to be trusted)
2.- Storefront WebSite comes up with Welcome to Receiver Page
3.- User Clicks Install
?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 3.1.- Last Receiver Client needs to be installed on the Client Machine
4.- User gets prompt with External Protocol Handler Request Window.
6.- Google Chrome sends a GetDetectionTicket request to the Storefront Server.
7.- User Clicks Launch Application. “Remember my choice”. (Meanwhile “GetDetectionStatus” requests are sent from the client)
8.- The Ticket from StoreFront is received, with information of URL to send the information from next step.
?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? clientDetectionTicket: "CDT_NYW4PYYWhdS34wu4yjMcNLowSWx2K_pbwueJGdy0Onxe5!Yv05CrivjkG0PavyID",…}
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& clientDetectionTicket: "CDT_NYW4PYYWhdS34wu4yjMcNLowSWx2K_pbwueJGdy0Onxe5!Yv05CrivjkG0PavyID"
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& postbackUrl: "https://SFFQDN/Citrix/Store/clientAssistant/reportDetectionStatus"
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& serverProtocolVersion: "1"
9.- Citrix Webhelper Collects Local Receiver client information and submits the information to PostBackURL: https://SFFQDN/Citrix/Store/clientAssistant/reportDetectionStatus
10.- As soon as the local receiver information gets back to the StoreFront Server, then the logon screen should load on Google Chrome.
??&
From Client > NetScaler > Storefront:
1.- User browses to NetScaler Gateway URL (Site Needs to be trusted)
2.- NetScaler Logon Screen is presented for user to login.
3.- Once user logs in, the Install Window is presented.
4.- User Clicks Install
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& 3.1.- Last Receiver Client needs to be installed on the Client Machine
5.- User gets prompt with External Protocol Handler Request Window.
6.- Google Chrome sends a GetDetectionTicket request to the StoreFront Server.
7.- User Clicks “Launch Application”, and if desired “Remember my choice”
8.- StoreFront Sends a Ticket Request to the STA Server and ticket ID from STA is added to the Response to the Client. (Meanwhile “GetDetectionStatus” requests are sent from the client)
9.- The ticket from StoreFront is received, with information of URL to send the information from next step.
?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? {clientDetectionStaTicket: ";10;STA405053580;5274A302239B7013B77B705DB42502",…}
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& clientDetectionStaTicket: ";10;STA405053580;5274A302239B7013B77B705DB42502"
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& clientDetectionTicket: "CDT_tJTGy6lL60out9JfZFtrcLowSWx2K_pbwueJGdy0Onxe5!Yv05CrivjkG0PavyID"
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& postbackUrl: "https://NSGFQDN/Citrix/Store/clientAssistant/reportDetectionStatus"
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& serverProtocolVersion: "1"
10.- Citrix Webhelper Collects local Receiver client information and submits the information to "https://NSGFQDN/Citrix/Store/clientAssistant/reportDetectionStatus" using HTTP SOCKS5 connection.
??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& ??& 9.1.- the Data Collected includes STA ID and Ticket ID as shown in Step 8.
11.- Once the NetScaler receives this request, The NetScaler Sends a "RequestData" POST request to STA “POST /Scripts/ctxsta.dll” Server to validate the ticket ID submitted from the Webhelper.
12.- The STA Responds with ticket information and Requester Server information (in this case the Storefront Server FQDN sf.vflab.com:443) within the "ResponseData"
13.- NetScaler contacts sf.vflab.com (SF FQDN) to validate the ticket as well. (Make sure SF FQDN resolves properly from NS CLI/Shell)
14.- NetScaler Expects the WebHelper Collected information from client to submit it to the Storefront Server.