javascript - WebSocket on IE10 giving a SecurityError

Question

I am currently developing a website under IE10 (on Windows 8), using WebSockets in JavaScript. It runs fine under Firefox 18 and Chrome 25, but on IE10 I get a SecurityError when I establish the connection.

What I am doing seems pretty straghtforward :

websocket = new WebSocket('wss://hello.dev.mydomain.net');

But IE doesn't like it :

SCRIPT5022: SecurityError 

The script is on "https://test.dev.mydomain.net" (not the real address obviously).

What bothers me is that if I just double-click the file on my local computer (e.g. file://...) it just works. Even worse: if I use fiddler to monitor HTTP traffic... it also works. Whereas there seems to be no connection at all without fiddler, as detailed in the API's specs. (See below.)

Judging by websocket spec, the exception should also appear on Chrome/Firefox... but it does not. So I doubt it has anything related to HTTP/HTTPS. In any case, I am using a wsS socket on a httpS page... Moreover: when I replace the wss address by another valid server found on an online example, it works.

I don't know if this is relevant, but the IP from test.dev.mydomain.net is 10.14.x.x where hello.dev.mydomain.net is 194.247.x.x. I don't know if it could trigger some kind of security on IE only...

One more thing: I have a certificate for *.dev.mydomain.net, IE does not seems to have problems with it. The script originally resides on a server called my.name.dev.mydomain.net, but since I am accessing it from another URL (I got a redirect since we first thought it could have been some kind of Same Origin Policy issue), I don't see how it could matter. At least I hope it does not...

Any idea is welcomed.

EDIT: adding the sites to the trusted zone does not work either.

Answer 1

It looks like IE throws a SecurityError if you're trying to open a websocket on a local (intranet) domain. To overcome this, you may disable IE's automatic algorithm for recognizing local sites. This can be done in Tools > Internet Options > Security > Local Intranet > Sites.

Uncheck all checkboxes (or only a particular one, if you know how exactly your domain did end up in intranet ones).

Note that IE uses (among other things) its proxy settings to determine local sites: if your domain is listed as excluded from proxying in proxy settings, then it will probably be treated as intranet one. This is why WebSockets work if you enable Fiddler: it modifies IE proxy settings and thus the list of intranet sites changes.