Mini WTF. How many people does it take to ping a test computer?



  • Apparantly 3 people at Initech.

    Situation is like this:  windows laptop + company network (10.x.x.x) + an extra network PCMCIA card for the test network (192.x.x.x). The idea is to isolate traffic from the company's net.

    Your boss walks by and suspects your test packets are routed through the company's network instead of staying on the test net, but has no proof.

    You want to 'prove' him wrong by demonstrating what happens when you unplug the company's network. A ping to the test machine would still work, because it wasn't routed through the company's net anyway, right?

    H:>ping 192.168.0.4

    But, oh no!!! It doesn't work!

    I don't want to spoil the 'fun', so I'll leave it as an exercise to the reader why this is a WTF 😉




  •  The only possible WTF can think of is that you have packets to 192.168.0.0/16 routed through a gateway on 10.0.0.0/16 instead of the card on 192.168.0.0

    What did <font face="courier new,courier">netstat -r</font> or <font face="courier new,courier">route print </font>show you?



  • @niwde83 said:

    I'll leave it as an exercise to the reader
     

    You know my doctor told me I should get more exercise. Or did I hear him say exorcize? I'm not really sure. Either way its not working as I'm not feeling healthier. WTF!? 



  • First ever post here - and I'm very concious of looking like a dick - but the only thing I can think of is that the wrong cable was unplugged?

    I look forward to checking back for devastating crtiticism later.



  • @PJH said:

    What did <font face="courier new,courier">netstat -r</font> or <font face="courier new,courier">route print </font>show you?

     

     

    Hint: that didn't work either 



  • @poons said:

    First ever post here - and I'm very concious of looking like a dick - but the only thing I can think of is that the wrong cable was unplugged?

    The right cable was unplugged.



  • @niwde83 said:

    @PJH said:

    What did <font face="courier new,courier">netstat -r</font> or <font face="courier new,courier">route print </font>show you?

     

    Hint: that didn't work either 

    What do you mean 'didn't work'? Neither command actually worked? The results of the commands wouldn't give a clue as to what's wrong?

    Neither command actually changes anything, so of course they won't 'work' as such.



  • Okay, I'll bite: they typed it into Notepad. Or entered it as the URL in a web browser or something.



  • What happens when the network for corpnet is reestablished?


    In the meantime I guess; Firewall? Glitchy driver depends on other network connection to be alive? Target host is down?



  •  

    There WAS no test network, and every single testers computer also connected to both networks?

     

     



  • The laptop's internal wireless device was silently connected, and everyone forgot it?



  • Actually a very nice try!

    Notice the current working directory while doing all this stuff...  Yes, it's subtle.

     



  • Obviously,  H: was a network drive mounted from some server on the production network.

    And the error you got was "The current directory is invalid"

     edit: And actually it's not that much of a WTF, atleast the error is sane... under linux trying to run something from a dead NFS mount just freezes your session for a few minutes.



  • I guess there was an executable in H:\ called ping.exe (or .bat or .com or .cmd) and it got executed instead of the right one...



  • Microsoft Windows XP [Version 5.1.2600]
    (C) Copyright 1985-2001 Microsoft Corp.

    C:\>y:
    The system cannot find the drive specified.

    C:\>subst y: c:\

    C:\>y:

    Y:\>subst y: /d

    Y:\>ping 127.0.0.1
    The current directory is invalid.

    -------------------------------------------------------------------------------------------------------------------------------------

    And how fitting that this is the message i got when i tried to post this reply:

    FILE_NOT_FOUND 

     




  • Y:&gt;ping 127.0.0.1

    The current directory is invalid.

     

    Right. So, it seems that Windows gives up looking for ping when the cwd is not accesible. 

    It isn't accesible, because they.... 😉




  • @bdew said:

    edit: And actually it's not that much of a WTF, atleast the error is sane... under linux trying to run something from a dead NFS mount just freezes your session for a few minutes.

     

    Right, this isn't a proper WTF. But too many people (all programmers) had to look at it before it was resolved! TRWTF is that I wasn't the person to discover it 😞
    Still a very funny moment when someone discovered it and everyone went "duh!"!

    About the Linux mount, if you boot diskless... your NFS session will continue eventually. Well... if you're lucky 😉

     

     



  • @bdew said:

    edit: And actually it's not that much of a WTF, atleast the error is sane... under linux trying to run something from a dead NFS mount just freezes your session for a few minutes.

    Under linux this behaviour is configurable. You get to choose between having an error message come back, or having the program sit and wait and start working again when the server returns. You even get to choose the timeout.

    If you choose settings that you didn't like, that's your own silly fault. 



  • @asuffield said:

    Under linux this behaviour is configurable. You get to choose between having an error message come back, or having the program sit and wait and start working again when the server returns. You even get to choose the timeout.

    If you choose settings that you didn't like, that's your own silly fault. 

    IMHO freezing without any feedback or indication of the reason is not the right thing for a program to do, under any circumstancs and configuration



  • @niwde83 said:


    Y:&gt;ping 127.0.0.1

    The current directory is invalid.

     

    Right. So, it seems that Windows gives up looking for ping when the cwd is not accesible. 

    It isn't accesible, because they.... 😉


     

    Here comes captain obvious! The answer is: H drive was unavailable because they disconnected from the network, and H drive was mapped to something on the network.

    Now let's hope captain obvious was correct or captain obvious will have to go cut himself.


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