unable to call external payment gateway api via dotnet code

Ram Chenna 101

Hi All

Please provide your inputs, suggestions.

I have an application deployed in IIS and calling an external api service which is working via POSTMAN and as well as from browser.

But when the same API is called via code and executed via IIS through front end application, it gives an error as below

System.net.Http.HttpRequestException: No such host is known

System.net.Sockets.SocketException (11001): No such host is known

At System.net.Http.ConnectHelper.ConnectAsync(String host, Int32 port, Cancellationtoken cancellationtoken)

O/S: Windows Server 2019

IIS: IIS 10.0.xx

Front End app: React

Web services: REST APIs using Dotnet Core 3.1 hosted on IIS

Database: SQL Server 2017

POSTMAN: works

Browser: works

But when the code executed via IIS it gives us the above error.

Any help

thanks

ram

Renjith renj 0 Reputation points

2024-01-09T06:54:11.6633333+00:00

Have you found a solution for this problem, as I am also having it?
Lex Li (Microsoft) 5,322 Reputation points Microsoft Employee

2024-01-09T19:43:15.0166667+00:00

Is there a proxy required to access that external URL? If so, it's normal to see POSTMAN and browser works but IIS fails, because web apps on IIS do not automatically use the same proxy settings. Ask your server/net administrators for assistance.

BTW, you shouldn't use .NET Core 3.1 as it reached end of life. .NET 6 or 8 is what you should upgrade to.
Renjith renj 0 Reputation points

2024-01-11T05:50:53.4+00:00

Problem appears only in production environment; a proxy appears to exist. How can we manage this in iis hosted web apps ? I have already tried using the defaultproxy settings in web.config, but no change
Lex Li (Microsoft) 5,322 Reputation points Microsoft Employee

2024-01-12T07:53:32.0166667+00:00

"I have already tried using the defaultproxy settings in web.config, but no change" is expected. You were configuring the legacy ASP.NET 4.x settings in web.config, which ASP.NET Core simply ignores. You will have to configure proxy server(s) explicitly in code, when initializing HttpClient instances. You can learn more from search engines.

2 answers

Ken Tucker 5,851 Reputation points

2022-01-21T10:08:20.017+00:00

Sounds like a DNS issue on the server the web site is hosted on. Maybe add a host file entry for the url you are trying to hit on the web server(s)

https://www.sharepointdiary.com/2014/10/how-to-add-host-file-entry-using-powershell.html#:~:text=How%20to%20Add%20HOST%20file%20Entry%20using%20PowerShell%3F,the%20contents%20of%20the%20Hosts%20file%20%24File%20
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Ram Chenna 101 Reputation points

2022-01-21T10:48:23.833+00:00

Hello,

Thanks so much for the reply.

As a first step we made an entry into the c:\windows\systems32\drivers\etc\hosts file

Remote IP Address (of payment gateway site) name of the host/server

Still it did not work and gave us the error.

we are confused, how come POSTMAN and the CHROME browser is able to make the API call and return the response.

And what is it that code in IIS is stopping to execute and giving an error as host not found

Thanks
Ram
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AgaveJoe 27,696 Reputation points

2022-01-21T12:57:16.577+00:00

Can you clarify? You installed PostMan and Chrome on the server and both applications can access the api URL from the server? If so, then there is a problem with the code. Most likely the URL is incorrect. What is the URL the application is trying to access?
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Ram Chenna 101 Reputation points

2022-01-21T14:36:48.907+00:00

External API: https://some-paymentgateway.com/api/v1/jnp-add/epayment/create

Payload details
{
"userid": 222,
"roleid": 26,
"paymentmethod": "online"
}

works well in POSTMAN using POST method and returns a token to indicate payment has been successful done along with 200 ok as the status code.

AgaveJoe 27,696 Reputation points

2022-01-21T15:32:20.87+00:00

Try adding the www; https://www.some-paymentgateway.com

Also, you did not answer the question. Are you running PostMan from the server?

Ram Chenna 101 Reputation points

2022-01-21T15:42:50.983+00:00

Hello,

Yes
We ran the POSTMAN from the our laptop as well as from the server.
and it works well.

Ok you suggestion is to add www.before the domain name.

Thanks
Ram

AgaveJoe 27,696 Reputation points

2022-01-21T16:25:37.883+00:00

If you can ping the payment gateway from the system where the code is running which I assume is Web API then there must be a bug in your code. Log the URL that is being called and make sure the URL is correct.

If you cannot ping the gateway then you have a DNS issue.

Jose Zero 576 Reputation points

2022-01-22T00:21:59.023+00:00

@Ram Chenna , if you get results in PostMan running at server, you do not have any DNS issue, check in your code if URL is correct.

I would suggest you try do your requests using RestSharp.
PostMan, provides many Code Snippets in different languages, right out the box, including RestSharp
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unable to call external payment gateway api via dotnet code

2 answers