Wireless hosts do not return ping


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Thread: Wireless hosts do not return ping

  1. #1
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    Question Wireless hosts do not return ping

    Hi. I have a weird problem in my LAN.

    The wireless connected hosts do not respond to pings from wired ones or other wireless ones. And all the wired connected hosts respond to pings from any wireless one. The same problem applies also to ssh connections exactly as in the ping issue.

    The switch the ADSL modem/router and the Access point are all 3 different machines correctly connected to each other.
    I do not have a firewall in any of my hosts, all run Slackware 13.1, the wireless ones use "wext" driver and not "ndiswrapper". All wireless hosts login successfully, WPA & DHCP works fine and internet connection goes without a problem. But the fact I can only connect from a wireless host to a wired one is puzzling. Any ideas?
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  2. #2
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    First off WPA is crap encryption for some time now, would do at least WPA2 if it is supported (unless you don't care about neighbors hijacking your signal). Just to give you an idea, here is a chart on the number of passwords per second that can be cracked from WPA.



    Just to make sure I'm understanding you, if you turn on all boxes and let DHCP assign addresses, you run ifconfig/iwconfig to get the IP addresses for each box's connection.

    Then if you are on a wireless box, you can ping and ssh a wired one, but you can't do the opposite? Also, no setting on the router is blocking pings (usually access your router config with 192.168.1.1 assuming 192.168.*.* network). I just want to make sure we are on the same page before I start pointing you in the wrong directions.
    "Whenever you find yourself on the side of the majority, it's time to pause and reflect."

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  3. #3
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    DHCP operates on the adsl modem router with a pool from 192.168.0.71 (to 90) and a static table based on NIC addresses for all my common PCs in the LAN. This is working correctly. For example, my wired desktop gets 192.168.0.1, my ancient wireless laptop 192.168.0.50, the new wireless netbook 192.168.0.55, my dad's downstairs's wireless laptop 192.168.0.51 and so on. Wired and wireless hosts get the DHCP response every time.
    The access point and the router are correctly configured to the network, wired to the switch and return pings correctly.

    Yes you are correct. The wired hosts can not ping or ssh the wireless ones. The opposite is working. No firewalling inside the LAN. iptables -L confirm this.

    The weird thing is that when the ancient laptop was operating Slackware 12.2 and ndiswrapper was used, I could ping and ssh it. Now that it runs Slackware 13.1 and native linux wireless modules and WEXT , it can be pinged some very very rare times. The netbook can never be pinged operating either Slackware 31.1 or its Windows 7 (firewall off). I kept Windows to do some checking of this kind.
    Last edited by micro; 07-23-2010 at 12:51 PM.
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  4. #4
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    Trilarian: If you use a random 10 character alphanumeric password for WPA (26 lowercase +26 uppercase + 10 numbers = 62 characters) that would give you 62^10 possible combinations which from your figures would take 507553 years to crack using the Tesla S1070. With a sufficiently strong password WPA is still pretty secure.

    Micro: Have you tried switching your ancient laptop back to the ndiswrapper drivers? Another thing you could try is turning all your wireless computers off, then turn off all your networking gear for 1 minute to reset it, turn the networking gear back on, and turn on just 1 wireless computer and see if you can ping that. If it works with just one computer connected wirelessly but not with multiple wireless computers it would indicate the network equipment doesn't like multiple computers connected wirelessly, perhaps because they seem to be coming through the same network interface as far as the switch and router are concerned, I don't see why it should be an issue, but I think it is a possibility.

  5. #5
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    I'll try to reset the switch.
    A question: If the single interface - multiple nics confuses the switch, then the access point (which is too given an ip address) shouldn't return pings either, as it is also on the "confusing" side, but it does.

    I will also try the ndisdriver again.
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  6. #6
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    Quote Originally Posted by retsaw View Post
    Trilarian: If you use a random 10 character alphanumeric password for WPA (26 lowercase +26 uppercase + 10 numbers = 62 characters) that would give you 62^10 possible combinations which from your figures would take 507553 years to crack using the Tesla S1070. With a sufficiently strong password WPA is still pretty secure.
    Sorry - trying to multitask and flipped WPA and WEP when reading. WEP is the culprit that is ridiculously easy to crack.

    Still, WPA uses TKIP (Temporary Key Integrity Protocol) which is susceptible to the man-in-the-middle approach on a high usage network (or patient observance of a low usage network). Anyway, without getting too far off topic, use WPA2 if your router offers it. It is an improvement of WPA, and we can have another thread about encryption if you wish - don't want to hijack micro's thread any further.

    EDIT =>
    I knew I wasn't crazy, WPA can be cracked in under a minute using the man-in-the-middle approach. Read up on the exploit here.
    /End Edit

    Have you tried the wl driver? I have it working on my netbook and it is able to be pinged.

    Sorry for the lack of useful information to your problem. I've been so swamped with work that I draw a blank by the time I finally get off (and the girlfriend is staring at me now to go out for supper). I wanted to at least respond so the next response will trigger an email to me and remind me to come back to this (my memory is shot these days). I had a similar issue at a friend's house that was resolved when he got a separate router (Linksys I think) instead of using the interface on the modem. I do believe there is a better solution for you though, he was just upgrading to N wireless and the problem resolved itself in the process.

    Anyway point being I'll try and put some more thought into this tomorrow - work load should be less. There are lots of smart guys here, so someone may even beat me to the punch.

    Best of luck.

    EDIT2=> What makes me curious rereading this is that you have the same problem on other boxes and a windows machine so it isn't driver specific. On the wireless, can you ping outside the network?

    Code:
    ping www.google.com
    Or if that fails, try their IP address.

    Code:
    ping xxx.xxx.xxx.xxx
    where
    Code:
    trilarian@Debian-Server:~$ resolveip www.google.com
    IP address of www.google.com is 74.125.45.103
    IP address of www.google.com is 74.125.45.104
    IP address of www.google.com is 74.125.45.105
    IP address of www.google.com is 74.125.45.106
    IP address of www.google.com is 74.125.45.147
    IP address of www.google.com is 74.125.45.99
    Last edited by trilarian; 07-27-2010 at 03:40 PM.
    "Whenever you find yourself on the side of the majority, it's time to pause and reflect."

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  7. #7
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    I solved it guys. I used a newer Access Point. There might be incompatibilities among the wireless nics and the AC. Everything pings everything else now! Maybe there was a problem between the various 800.11 signals (g,n etc)?
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  8. #8
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    Always good to see a happy ending.
    "Whenever you find yourself on the side of the majority, it's time to pause and reflect."

    -Mark Twain

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