How to fetch file by FTP via squid proxy using .NET Core (FtpWebRequest)?

Question

According to https://learn.microsoft.com/en-us/dotnet/api/system.net.ftpwebrequest.proxy?view=netcore-3.1 FtpWebRequest does not support proxy with .NET Core. Is there an alternative?

I need to access a FTP file via some squid proxy (i.e. FTP over HTTP) with proxy authentication (NTLM).

This is example code:

FtpWebRequest request = (FtpWebRequest) WebRequest.Create("ftp://ftp.ubuntu.com/");
var proxy = new WebProxy("my.squid.host", 8080);
proxy.Credentials = new NetworkCredential("squid_user", "squid_pass");
request.Proxy = proxy;
WebResponse response = request.GetResponse();

var result = new StreamReader(response.GetResponseStream()).ReadToEnd();
Console.WriteLine(result);

If you replace squid host/user/pass in this code with yours, you will see this works fine with this csproj file:

<Project Sdk="Microsoft.NET.Sdk">
    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net472</TargetFramework>
      </PropertyGroup>
</Project>

But it no longer works with .NET Core:

<Project Sdk="Microsoft.NET.Sdk">
    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>netcoreapp3.1</TargetFramework>
      </PropertyGroup>
</Project>

Answer 1

There's no other FTP implementation in .NET framework than FtpWebRequest. And FtpWebRequest itself is deprecated and won't be improved. You have to use a 3rd party FTP client library.

See:

• https://learn.microsoft.com/en-us/dotnet/api/system.net.ftpwebrequest#remarks and
• https://github.com/dotnet/platform-compat/blob/master/docs/DE0003.md (which points to Free FTP Library)

---

In general, you can use FluentFTP or my WinSCP .NET assembly.

Though neither supports NTLM authentication (a requirement you have added later). I'm not aware of any other free widely used .NET FTP library.