Wireless issue - cannot establish new connections suddenly

Discussion in 'Networking and Computer Security' started by NeloForster, Apr 12, 2009.

  1. Anti-Trend

    Anti-Trend Nonconformist Geek Staff Member

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    No dude, the CPU doesn't broadcast a radio signal at 2.4GHz, I promise. It just happens to strobe at that frequency. :)
     
  2. donkey42

    donkey42 plank

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    apologies, i'll monitor the post, and leave you in AT's capable hands

    i misread wiki then :doh:
     
  3. NeloForster

    NeloForster Source of Exyphetadolamin

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    Well I can see why it would cause some confusion. Having the same measurement name for two different things is just asking for trouble.
     
  4. donkey42

    donkey42 plank

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    i know i said i'd leave it to AT, but i can't stop myself, as AT suggested "network stack" i wondered if you reset the network stack with WinSockFix does it work ?

    Edit: try
    Code:
    ipconfig /renew
    that will determine if the net stack is corrupt, if the returned message is something like
    then your stack is probably corrupt

    Source

    Edit: or it could be a corrupt WINSOCK2

    Edit: do you have your XP CD ?
     
  5. donkey42

    donkey42 plank

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    read this & use it if you think it relevant
     
  6. Anti-Trend

    Anti-Trend Nonconformist Geek Staff Member

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    "Network stack" is just an an easy way to say "all the bits of the operating system that allow it to talk to other computers". In the case of Windows, this of course includes winsock, etc. And he's already reinstalled the OS, so while malware is still a possibility (as it must always be when dealing with MS products), it's unlikely to be the culprit in this case.
     
  7. donkey42

    donkey42 plank

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    well i was over complicating (as usual) although networking is very complex, and i'm still struggling with the relationship between the theory & the practical application of the theory

    but if i were to guess, i'd say it was a prob with DNS, but as AT said it could be malware, so to totaly eliminate malware from the equation scan with MalwareBytes.org (obviously scan after updating definitions) then download Wireshark & upload the pcap here as AT has already said

    P.S. yes i am a plank :doh:

    BTW: to help you understand the theory of networking look here

    Edit: NeloForster, look here and you may figure it out
     
  8. NeloForster

    NeloForster Source of Exyphetadolamin

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    Hi guys,

    Thanks for the suggestions. I wasn't alerted that any more responses were posted, so unfortunately I didn't get to try the suggestions in the last two or three posts while the problem was occurring again.

    Figures it's a DNS thing. During the time I changed my DNS servers to those belonging to Pipex, the problem didn't happen. I thought I'd give OpenDNS a try as my colleague mentioned ping response times got a lot lower for him, but after a while ping response times reached an all-time high for me, so I just thought I'd set my DNS as Automatic again, which fixed the slow ping response times.

    Now the problem has just ocurred again, about half an hour ago. However, a DNS change (to 4.2.2.1) has made everything work fine again - perhaps it's a problem with one or more of my ISP's nameservers (the ones used when automatic is selected)?

    I have added the Wireshark logs I recorded whilst pinging stuff, or trying to navigate in Firefox. Pinging IP's works fine, but pinging domain names returned errors.

    Do the logs confirm the DNS problem? Or is there something I'm not seeing which could point to something else being the issue?


    Cheers!
     

    Attached Files:

  9. Anti-Trend

    Anti-Trend Nonconformist Geek Staff Member

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    DNS and ping times are completely unrelated; DNS cannot affect ping times whatsoever. DNS is Domain Name System, meaning resolving domain names to IP addresses. That's really all it does. So while a slow DNS server can make surfing seem slow (while you wait to resolve hostnames to IPs so you can connet to the IP), once you have the IP the connection happens at the IP level and DNS is no longer involved. Same with ICMP echo requests, i.e. "ping". If you ping a host by name rather than IP, a DNS lookup must take place before you can actually ping it; you have to get its IP. Once your host knows the address, the connection happens over IP, so DNS doesn't affect ping times. If you can't resolve a host though due to DNS problems, obviously you can't ping a host by its domain name, since your system can't lookup its IP to ping it in the first place. I hope this clears things up rather than making it seem more confusing. :O

    Yeah, that could be. If you have more than one DNS server defined and one fails, it will try the next and the next until you get resolution. If connectivity with more than one fails at once, Windows inparticular seems to have problems with name resolution until the local DNS cache is flushed. If you see the issue again, try running the following command:
    Code:
    ipconfig /flushdns
    I haven't looked over the TCP dump yet, but the fact that you can ping IPs but not do name resolution indicates a DNS problem all right!
     
  10. Anti-Trend

    Anti-Trend Nonconformist Geek Staff Member

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    The logs confirm.... that you didn't do a proper packet capture! :( There isn't much there for me to see; this is a very basic capture in plain text format.
     
  11. donkey42

    donkey42 plank

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    i've just found out that Vista, XP & Win Server 2k3 has a problem within tcpip.sys, luckily there is a patch here (and a description) have a look at it & apply the patch,

    any more probs your always welcome @ HWF

    Source
     

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