I have a simple Asp.Net Core Azure Web App that needs to make a http get request to an on-premise Rest service. This Rest service is hosted on IIS with bindings set only for port 443. I've setup a new Hybrid Connection in Azure and added it to the Web App. At the on-prem side, I've installed Hybrid Connection Manager and entered the connection string for the Hybrid Connection - this now shows as "Connected".
Problem is, when executing the line of code that makes the get request, the following error is thrown:
System.AggregateException: One or more errors occurred. (No such host is known) ---> System.Net.Http.HttpRequestException: No such host is known ---> System.Net.
There's an interesting blog post here: Microsoft Blog which states that the connections should be setup without using the fully qualified domain name (FQDN) - server name suffixed with organisation.co.uk. However, as far as I can tell, the SSL certificate for the Rest service requires the FQDN - otherwise it presents the error
There is a problem with this website’s security certificate
Does anyone know how to troubleshoot and work around this problem?
The first error is probably a DNS issue. As that blog mentioned
If you are using a fully-qualified domain name, you need to ensure that it’s a name that can be resolved within your local network. (In some cases, customers are running DNS in the local network, and it’s that local DNS service that resolves the name.)
So, If you have to use FQDN in the connection string for the Hybrid Connection. You could use an FQDN which only could be resolved by local DNS service.
Alternatively, you could try to edit the hosts file to make DNS lookup preferably inside the on-premise network. Add a line in Rest service server hosts file (located in %WINDIR%\system32\drivers\etc) mapping the IIS server's IP to a name.
For example:
192.168.0.50 serverFQDN
More details, Refer to this.