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loopback and iis RRS feed

  • General discussion

  • I have been trying to learn how to work with network streams, and needed to echo messages to make sure I was sending and receiving ok.I work from home on a laptop and do not have any servers available to work with.As I could not find any active echo servers , i decided to install the Microsoft Loopback Detector.I thought it would function like a hard wired rs232 loopback plug, but it's turned out to be much more difficult than using Hyper Terminal and serial ports.

      The ip address for the loopback detector was set to 10.0.0.10. It pinged fine.The Netstat -a command showed that there was an active port # 137 open.The Telnet command : O 10.0.0.10 : 137 was run , but the connection refused to open??

     Then i ran 10.0.0.10 in the browser and saw it opened the local iis.Setting up the IIS  seemed to work, as browsing internal files from a browser on 10.0.0.10 are ok. Example: Http://10.0.0.10:8080/temp/url.txt opened the text file with no problem at all.            Then I Ran NetStat -a again and found that nothing was listening on that port assigned in the iis (8080)?.Then  the Telnet command was run again :   O 10.0.0.10:8080 , but the connection was refused again.

     Then using the TCPCLient of c#,i sent a random string to the ip address , and did receive a message back saying that the string was in the wrong format:   <hr><p>HTTP Error 400. The request verb is invalid.</p>      Then I tried to get the url.txt file by sending a string: " GET /temp/url.txt HTTP/1.1 \r\n". Nothing doing.No error this time,but no reply at all.

     How do I set IIS up to receive and send back messages, or to function as a loopback ?

    Thanks for reading these long winded  ramblings.I'm just finding TCP networks really hard to work with.Any help will be much appreciated.


    Thanks in advance for helping with my questions. Johann
    Friday, November 26, 2010 7:06 AM

All replies

  • I have been trying to learn how to work with network streams, and needed to echo messages to make sure I was sending and receiving ok.I work from home on a laptop and do not have any servers available to work with.As I could not find any active echo servers , i decided to install the Microsoft Loopback Detector.I thought it would function like a hard wired rs232 loopback plug, but it's turned out to be much more difficult than using Hyper Terminal and serial ports.

    I understand that you need a loop back server in your machine and want to test some client functionality against this. Correct me I my understanding is not correct

      The ip address for the loopback detector was set to 10.0.0.10. It pinged fine.The Netstat -a command showed that there was an active port # 137 open.The Telnet command : O 10.0.0.10 : 137 was run , but the connection refused to open??

    Very well ossible that Windows Firewall is blocking the Telnet prototcol. Please check.

     Then i ran 10.0.0.10 in the browser and saw it opened the local iis.Setting up the IIS  seemed to work, as browsing internal files from a browser on 10.0.0.10 are ok. Example: Http://10.0.0.10:8080/temp/url.txt opened the text file with no problem at all.            Then I Ran NetStat -a again and found that nothing was listening on that port assigned in the iis (8080)?.Then  the Telnet command was run again :   O 10.0.0.10:8080 , but the connection was refused again.

    This is a different problem. You have configured IIS port as 8080 and trying to access it from Browser. Check whether you can access by mentioning http://localhost:8080/temp/url. If you can then it means that Windows Firewall is blocking port 8080. 

     Then using the TCPCLient of c#,i sent a random string to the ip address , and did receive a message back saying that the string was in the wrong format:   <hr><p>HTTP Error 400. The request verb is invalid.</p>      Then I tried to get the url.txt file by sending a string: " GET /temp/url.txt HTTP/1.1 \r\n". Nothing doing.No error this time,but no reply at all.

     How do I set IIS up to receive and send back messages, or to function as a loopback ?

    My recommendation is that dont use IIS for such loopback experimentation. It is not meant for that. Install some loopback server program and check your program. You can get a number of loopback server programs like:

    Simple C# Echo Server - http://www.dreamincode.net/forums/topic/56828-tcpip-echo-server/

    Simple HTTP Echo Server - http://www.java2s.com/Tutorial/CSharp/0580__Network/AsimpleHTTPechoserver.htm

    Thanks for reading these long winded  ramblings.I'm just finding TCP networks really hard to work with.Any help will be much appreciated.

    It is not that tough. You are always welcome with further clarifications


    Thanks in advance for helping with my questions. Johann


    S V Krishnan
    Tuesday, November 30, 2010 9:55 AM
  • Hi SV, Thanks very much for the reply, and the links.I'll try the links.

    I tried switching off the windows as well as the AVG anti virus resident shield. No different. I still cannot connect with Telnet.

    The browser command http://10.0.0.10:8080/temp/url.txt does work with no problem. using localhost for 10.0.0.10 does not work, although localhost does work for 127.0.0.1 on port 80.I think localhost is only assigned for that ip address?

    Why does my GET verb not work( that I gave in the above sample )?What strings are the browser sending to get to the temp folder? I must be sending the wrong string? regards


    Thanks in advance for helping with my questions. Johann
    Wednesday, December 1, 2010 11:23 AM
  • You can use wireshark to sniff the transaction & analyze the issue better.
    Thursday, December 2, 2010 6:49 AM