Azure Service bus - queue connectivity error

Question

I am trying to connect and send a message to azure service bus queue using the following code

var connectionString = "<Your connection string>";

var queueName = "<Your queue name>";

var client = QueueClient.CreateFromConnectionString(connectionString, queueName);
var message = new BrokeredMessage("This is a test message!");
client.Send(message);

This is the same code they have on their site as an example.

But while connecting, it gives an SSPI ERROR with an inner exception of 'The client and server do not possess a common algorithm'.

Also, I have disabled TLS 1.0 and SSL 3.0 in my system. Is it because of that.

Can someone help me understand what is wrong here?

Where is your application running (what host)? Do you have a firewall in place? Default connectivity mode is TCP, so perhaps the ports are getting blocked. More on connectivity mode here: msdn.microsoft.com/en-us/library/… There's also another thread with a similar question: stackoverflow.com/questions/35469739/… — Sean Feldman
@Sean Feldman my application is running on azure web apps, but this issue is when I am trying it locally on my IIS host..on my machine..I haven't tried after deploying it. I have also tried changing service bus environments, but with no luck. — Tom

evilSnobu evilSnobu · Accepted Answer · 2016-10-06T10:31:45

The client and server do not possess a common algorithm

That's not a TCP layer problem. That's higher up in the TLS handshake and it means just that. The two parties (client and server) could not agree on a common cipher suite and the handshake failed.

Run your client's host through SSLLab's browser test (even if it's not a browser): https://www.ssllabs.com/ssltest/viewMyClient.html

Then run the Service Bus endpoint through the server test page:
https://www.ssllabs.com/ssltest/

Compare results and enable at least one cipher suite in your client that matches what the TLS stack on the Service Bus endpoint accepts.

You should also simply try doing:

System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

..since you've disabled TLS 1.0 and i'm no longer sure what your .NET now defaults to, so explicitly setting the protocol version is the natural way to go.

TLS 1.2 was released back in 2008. You can be sure Azure supports it for all services, globally - check your own Service Bus namespace here! (same story for 935x/TCP).

It's not enough to support TLS 1.2, your host must have at least one common cipher suite with the server -- use this to check your host:

https://github.com/snobu/get-schannel-ciphers (.exe under /Release/)

Azure Service bus - queue connectivity error

2 Answers