I'm working on building a Silverlight application whereas we want to be able to have a client hit a url like:
http://{client}.domain.com/
and login, where the {client} part is their business name. so for example, google's would be:
http://google.domain.com/
What I was wondering was if anyone has been able, in silverlight, to be able to use this subdomain model to make decisions on the call to the web server so that you can switch to a specific database to run a query? Unfortunately, it's something that is quite necessary for the project, as we are trying to make it easy for their employees to get their company specific information for our software.
Wouldn't it work to put the service on a specific subdomain itself, such as wcf.example.com, and then setup a cross domain policy file on the service to allow it to access it?
As long as this would work you could just load the silverlight in the proper subdomain and then pass that subdomain to your service and let it do its thing.
Some examples of this below:
Silverlight Cross Domain Services
Silverlight Cross Domain Policy Helpers
On the server side you can check the HTTP 1.1 Host header to see how the user came to your server and do the necessary customization based on that.
I think you cannot do this with Silverlight alone, I know you cannot do this without problems with Javascript, Ajax etc. . That is because a sub domain is - for security reasons - treated otherwise than a sub-page by the browsers.
What about the following idea: Insert a rewrite rule to your web server software. So if http://google.domain.com is called, the web server itself rewrites the URL to something like http://www.domain.com/google/ (or better: http://www.domain.com/customers/google/). Would that help?
Georgi:
That would help if it would be static, but alas, it's going to all be dynamic. My hope was to have 1x deployment for the application, and to use the http://google.domain.com/ idea to switch to the correct database for the user. I recall doing this once when we built an asp.net website, using the domain context to figure out what skin to use, etc.
Ates: Can you explain more about what you are saying... sounds like you are close to what I am trying to come up with. Have you seen such a tutorial for this?
The only other way I have come up with to make this work is to have a metabase that when the user logs in, it will switch them to the appropriate database as required... was just thinking as well that telling Client x to hit:
http://ClientX.domain.com/ would have been sweeter than saying to hit http://www.domain.com/ and login. It seemed as if they were to hit their name, and to show it personalized for them right from the login screen would have been much more appealing for the client base.
#Richard B: No, I can't think of any such tutorial that I've seen before. I'll try to be more verbose.
The server-side approach in more detail:
Direct *.example.com to the same IP in your DNS settings.
The backend app that handles login checks the Host HTTP header (e.g. the "HTTP_HOST" server variable in some platforms). That would contain the exact subdomain.example.com that the client used for reaching your server. Extract the subdomain part and continue...
There can also be a client-side-only approach. I don't know much about Silverlight but I'm assuming that you should be able to interface Silverlight with JavaScript. You could read document.location with JavaScript and pass it to your Silverlight applet, whereon further data fetching etc. logic would rely on the subdomain that was passed in by JavaScript.
#Ates:
That is what we did when we wrote the ASP.Net system... we pushed a slew of *.example.com hosts against the web server, and handled using the HTTP headers. The hold-up comes when dealing with WCF pushing the info between the client and the server... it can only exist in one domain...
So, for example, when you have {client}.example.com and {sandbox}.example.com, the WCF service can't be registered to both. It also cannot be registered to just *.example.com or example.com, so that's where the catch 22 is coming in at. everything else I have the prior knowledge of handling.
I recall a method by which an application can "spoof" another domain name in certain instances. I take it in this case, I would need to do such a configuration? Much to research yet I believe.
Related
I run Google Ads on my Google-App-Engine-hosted website (www.bigriddles.com), and they tell me I need to have an "ads.txt" file served from the root domain (i.e. http://bigriddles.com/ads.txt, as opposed to http://www.bigriddles.com/ads.txt).
My DNS is hosted on Gandi, and I created their "ALIAS" record (which I think just does CNAME flattening or something similar) to alias "bigriddles.com" to "ghs.googlehosted.com." I chose "ghs.googlehosted.com" because that's what I CNAMEd "www.bigriddles.com" to (many years back), and that CNAME has been working fine.
However, now when I visit "bigriddles.com", I get an "HTTP 301 Moved" to "www.bigriddles.com", and as far as I can tell, this response isn't coming from any code I wrote (I've looked through my code and don't see anything that would redirect this). Furthermore, there is a "Server: ghs" header in the response from "bigriddles.com", whereas if I visit "www.bigriddles.com", which works fine, the response includes the header "Server: Google Frontend". I'm not sure if there is some hint of my problem in the difference between those two Server headers.
Anyway, I'm not sure exactly what's going wrong. It could be a DNS issue. I say this because "dig www.bigriddles.com" comes back with the IP 172.217.14.115, whereas "dig bigriddles.com" comes back with "172.217.168.211", so maybe one of these really is a "ghs" server and the other is a "Google Frontend" server (I'm not sure the difference) and this "ALIAS" DNS solution just isn't going to work.
More likely though I feel like maybe there is just some settings problem with my App itself where it's not set up to allow the apex domain "bigriddles.com", and if I change that setting it will start working?
I have gone through the steps on https://cloud.google.com/appengine/docs/standard/python/mapping-custom-domains. When I view the "Custom Domains" for my project, I see "www.bigriddles.com" and "m.bigriddles.com", but I don't see the naked domain "bigriddles.com". However, when I try to add it on that page, it tells me that "bigriddles.com" is already mapped to a project, so I'm not sure what to make of that.
Any help would be appreciated, thank you!
This seems like an issue with your domain provider.
You can use this tool that might help you contact the domain provider with detailed info.
If they insist it's not an issue on their side (I strongly believe it is), then you should contact Google Cloud Platform Support so a deeper inspection can be made on your project.
If you're also using G Suites for your domain, the criminal is G Suites' Domain -> Redirect. If it is, it's a pity that Google does not let us turn off the so-called feature.
Since G Suites use as the same entry point as App Engine, you have no chance to solve this other than moving your site outside Google services or stop using G Suite.
I'm doing https web requests in silverlight using "WebRequest"/"WebResponse" framework classes.
Problem is: I do a request to an url like: https://12.34.56.78
I receive back a versign signed certificate which has as subject a domain name like: www.mydomain.com.
Hence this results in a remote certificate mismatch error.
First question: Can I somehow accept the invalid certificate, and get the WebBresponse content ? (even if it involves using other libraries, I'm open to it)
Additional details: (for those interested on why I need this scenario)
I'm trying to give a client access to a silverlight app deployed on a test server.
Client accesses the silverlight app at: www.mydomain.com/app
Then I do some rest requests to: https://xx.mydomain.com
Problem is I don't want to do requests on https://xx.mydomain.com, since that is on our productive server. For this reason I use https://12.34.56.78 instead of https://xx.mydomain.com.
Client has some firewalls/proxies and if I simply change his hosts file and map https://xx.mydomain.com to 12.34.56.78, web requests don't resolve to the mapped IP.
I say this because on his network webrequests fail if I try that, on my network I can use the hosts changing without problems.
UPDATE: Fixed the problem by deploying test releases to an alternative: https://yy.domain.com and allowing the user to configure for test purposes, the base url to which I do requests to be: https://yy.domain.com.
Using an certificate that contained the IP in the subject or an alternative subject would've probably worked too, but would have cost some money to be issued by a certified provider and would not be so good because IP's might change.
After doing more research looks like Microsoft won't add this feature too soon, unless there's a scenario for non-testing/debugging uses.
See: http://connect.microsoft.com/VisualStudio/feedback/details/368047/add-system-net-servicepointmanager-servercertificatevalidationcallback-property
I'm working on a Windows Phone 7 application that makes a REST service call. The third party that hosts the web services has an invalid certificate in the current environment. When I hit the URL in Firefox, I get a warning about the cert and I am asked if I want to continue. I'm also using the Poster FF extension to test the call. It works with Poster if I first accept the invalid cert in Firefox. If I don't, then POSTER wont make the request.
In my WP7 Emulator, I can't make the request at all. I get a 404 at the EndGetResponse method. I making the same request as in Poster, so I know there is nothing wrong with the request. I have successfully hit another web service using the same code (no certs involved), so I don't think it's the code. The only thing I can think of is that WP7 doesn't allow requests to an invalid cert. Has anyone had experience with this situation? Is there any way around it?
Is there a way I can tell my app to accept all communication, even if there is an invalid cert?
There is sadly no way to do this on the phone. Ordinarily, i.e. on the desktop this simple line of code will disable certificate checking.
System.Net.ServicePointManager.ServerCertificateValidationCallback = (se, cert, chain, sslError) => { return true; };
If you look at the ServicePointManager on the phone, there's no callback to hook into. It's a massive pain in the arrrrse.
Have you considered writing to the service owner and asking why they're being bad internet citizens? (essentially, what you're seeing here is web security in action, for better or worse)
As Matt says, you might be able to code a simple relay on a web server. It doesn't have to be a special service, but maybe just a web page that does the call for you and spits out RAW text or XML. Your phone client just GETs this page and picks through the response manually.
Where there's a will there's a way.
Luke
You need to install the root CA cert of the issuing party on the phone.
You can do this by emailing the RootCA to the user of the phone. They click on the attachement and it will prompt them to ask if they want to install the certificate on the phone.
Once you have done that your requests should go through.
I dont believe there is a way to do this programatically in your app however.
I'm not aware of a way to install additional certificates on the phone.
In this situation I'd create a proxy service between your app and the 3rd party site and have your app call that. If you need to, you could put the proxy behind a valid cert.
Ok,
I have developed this WinForms client, which interacts with a server (ASPX Application) by means of WCF calls. I would now like to deploy the server to my shared webhost, but I'm kinda new to WCF and especially the security possibilities behind it.
The goal is to kind of secure the WCF service, so that not everybody that knows or finds out the endpoint address can call it. Rather, only my WinForms client must be able to call the WCF service.
I do not need authentication on a user basis, so no authentication is required from the user of the client. But I want only instances of this WinForms client to be able to interact with the service. The information passed between server and client is not very sensitive, so it's not really required to secure it, but it's a plus if it can easily be done.
Is this possible with a Shared Host (IIS) environment (no HTTPS at disposal) ? What bindings and options should I use ? I suppose wsHttpBinding, but how would I setup the security options ?
Using .NET 4.0
Thanks
From what I understand, you have an internet-facing service which you want to limit to only your client app to be able to call - correct? Or do you envision other clients (like PHP, Ruby etc.) also wanting to call into your service at some point?
To secure your message, you have two options in WCF - message or transport security. Over the internet, with an unknown number of hops between your client and your service, transport security doesn't work - you're left with message security (encrypting the message as it travels across the 'net). For this to work, you typically add a digital certificate to your service (only server-side) that the client can discover and use to encrypt the messages with. Only your service will be able to decrypt them - so you're safe on that end.
The next point is: who can call your service? If you want to be totally open to anyone, then yes, you need wsHttpBinding (or the RESTful variant - webHttpBinding). If you want to allow non-.NET clients, you're typically limited to no authentication (anyone can call), or username/password schemes which you will validate on the server side against a database of valid users.
If you only want to allow your own .NET client in, then you can do several things:
disable metadata on your service; with this, you would "hide" your endpoints and the services they provide - someone using a "metadata scanner" (if that exists) wouldn't be able to just stumble across your service and find out what methods it provides etc. This however also makes it impossible for another developer outside your organization to do an Add Service Reference to your service.
you could define and use a custom binary http binding - only other clients with this setup could even call your service. The binary http binding would bring some speed improvements, too. See this blog post on how to do this.
you need to somehow identify those callers that are allowed in - one possible method would be to put an extra header into your WCF messages that you then check for on the server side. This would simply make sure that a casual hacker who discovers your service and figures out the binary http binding would still be rejected (at least for some time). See this blog post here on how to implement such a message inspector extension for WCF.
the ultimate step would be to install a digital certificate on the client machine along with your service. You would then set up your client side proxy to authenticate with the service using that certificate. Only client machine that have that certificate could then call into your service.
It really depends on how far you want to go - WCF gives you a lot of options, but you need to decide how much effort you want to put into that .
The first thing you need to ask your self is: "What can someone do to your WCF service if they connected their own customized client?" Look at all of the functionality that is being exposed via WCF and assume that it could be accessed at will. You have absolutely no control over the client, and you will never have this ability.
HTTPS is beautiful, its a damn shame that your forced to be vulnerable to OWASP A9: Insufficient Transport Layer Protection. If it where up to me, I would move to a different host that cared about security. If you are throwing usernames and passwords over the network, then your putting your users in danger.
One of the biggest problems I have seen with a WCF service is that they had a "executeQuery()" function that was exposed. The developer allowing the client to build queries to be executed by the server. This approach is fundamentally flawed as you are just handing your database over to an attacker. This type of vulnerability isn't SQL Injection, it falls under CWE-602: Client-Side Enforcement of Server-Side Security.
Along the same lines as CWE-602 is OWASP A4: Insecure Direct Object References. Could an attacker fool your WCF service into thinking its another user by providing a different user id? Are you trusting the client to tell the truth?
The next classification of vulnerabilities that you must take into consideration is OWASP A1: Injection, other wise known as "Taint and Sink". For instance if you are exposing a function where one of its parameters is being used in a CreateProcess() which is invoking cmd.exe. This parameter could be controlled by the attacker, and there for this variable is "tainted", the call to CreateProcess() is a "sink". There are many types of vulnerabilities along these lines, including but not limited to; SQL Injection, LDAP Injection, XPATH Injection. These types of vulnerabilities affect all web applications.
In ASP.NET, I usually log exceptions at server-side, In windows forms I can either log exceptions server-side or write to a log file on the client. Silverlight seems to fit somewhere in between.
I wanted to know what everyone else is doing to handle their Silverlight exceptions and I was curious if any best practices have emerged for this yet.
For real logging that you could store & track, you will need to do it on the server, since you can't be guaranteed anything on the client will be persisted.
I would suggest exposing a "LogEvent(..)" method on a server side web service (maybe you already have one) which would then do the same kind of logging you do in ASP.net
Here's a video about basic web service calls in Silverlight if you haven't done that yet
http://silverlight.net/learn/learnvideo.aspx?video=66723
I'm not sure about any logging best practices though, my first guess would be to do the best practicies for logging in a web sevice on the server and expose that to the client.
Hope this helps!
I would say that Silverlight fits much better to ASP.NET side of the model. You have server which serves web page. An object (Silverlight app) on the page pings data service to fetch data and display it.
All data access happens on the server side and it does not matter if data is used to create ASP.NET pages on the server or sent raw to the RIA for display. I do log any failures in data service on server side (event log works fine) and do not allow any exception to pass to WCF. When client does not receive expected data (it gets null collection or something similar), it display generic data access error to the user. We may need to extend that soon to pass a bit more information (distinguishing between access denied/missing database/infrastructure failure/internal error/etc), but we do not plan to pass exception error messages to the client.
As for client side, sometimes we may get in situation where async call times out -- it is just another message. For general exceptions from client code (typically, bugs in our code), I just pass exception to the browser to display in same manner as any script exception.
Also take a look at the new Silverlight Integration Pack for Enterprise Library from Microsoft patterns & practices. It provides support for logging exceptions to isolated storage or remote services and is configurable via policies in external config or programmatically. Batch logging and automatic retry (in case of occasionally connected scenarios) are also supported.
Use the Isolated Storage available for Silverlight application. You should store here your log.
Then you can develop a mecanism to send the user log to a webservice like the Windows bug report service.
It very much depends on the type of application that youre developing.
if its an mvc / mvp based architecture then your model, or most of it at least, will be on the server, and this is where most of your exceptions will be thrown i would imagine, so you can log them there and choose to display a message to the user or not.
for exceptions from the client you may want to know the details so just send them back.