Output log using FtpWebRequest

You can do this using Network Tracing. To set it up, create (or modify, if you already have one) App.config file, so that it looks like this (if you already have the file, you will need to add the settings to it):

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.diagnostics>
    <sources>
      <source name="System.Net" tracemode="protocolonly" maxdatasize="1024">
        <listeners>
          <add name="System.Net"/>
        </listeners>
      </source>
    </sources>
    <switches>
      <add name="System.Net" value="Information"/>
    </switches>
    <sharedListeners>
      <add name="System.Net"
        type="System.Diagnostics.TextWriterTraceListener"
        initializeData="network.log"
      />
    </sharedListeners>
    <trace autoflush="true"/>
  </system.diagnostics>
</configuration>

If you do this, your application will create a network.log file, that might look something like this:

System.Net Information: 1 : [8892] FtpWebRequest#2383799::.ctor(ftp://test/)
System.Net Information: 0 : [8892] FtpWebRequest#2383799::GetResponse(Method=LIST.)
System.Net Information: 0 : [8892] Current OS installation type is 'Client'.
System.Net Information: 0 : [8892] RAS supported: True
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Created connection from 192.168.1.1:51833 to 192.168.1.2:21.
System.Net Information: 0 : [8892] Associating FtpWebRequest#2383799 with FtpControlStream#33675143
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [220 This is the test FTP server. Authentication required.]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [USER svick]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [331 Password required for svick]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [PASS ********]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [230 Logged on]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [OPTS utf8 on]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [200 UTF8 mode enabled]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [PWD]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [257 "https://stackoverflow.com/" is current directory.]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [TYPE I]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [200 Type set to I]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [PASV]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [227 Entering Passive Mode (174,37,88,92,117,98)]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Sending command [LIST]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [150 Connection accepted]
System.Net Information: 0 : [8892] FtpControlStream#33675143 - Received response [226 Transfer OK]
System.Net Information: 0 : [8892] FtpWebRequest#2383799::(Releasing FTP connection#33675143.)

It’s quite verbose, but it does contain the information you need. If you want to modify how is the log file written, you can implement your own TraceListener and use that in the config file instead of TextWriterTraceListener.