Names not resolving - Networking

This is a discussion on Names not resolving - Networking ; Greetings. I have a very strange problem. I have a laptop, named weasel, with both wired ethernet (eth0) and wireless (eth1) interfaces. I use it at work on a LAN; the ethernet card is plugged into a router, whence it ...

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Thread: Names not resolving

  1. Names not resolving

    Greetings.

    I have a very strange problem.

    I have a laptop, named weasel, with both wired ethernet (eth0) and wireless
    (eth1) interfaces. I use it at work on a LAN; the ethernet card is
    plugged into a router, whence it gets an IP address via DHCP. I have
    another laptop, sable, with the same arrangement.

    This morning I came to work to find that the weasel's once-functional
    ethernet connection no longer resolves any domain names, be they names on
    the local network or on the Internet. However, I can still ping other
    machines (either on the LAN or on the Internet) provided I specify their
    IP addresses. Sable seems fine.

    I've tried to find the fault to no avail. Some things I've investigated:

    1) The physical connection seems fine. I tried swapping weasel's ethernet
    cable with that of my other machine, sable. Sable can still resolve names
    but weasel still can't. They're both using the same router.

    2) The actual network card seems fine. If I reboot weasel to Windows XP,
    it has no problems resolving names.

    3) No firewall is running on weasel.

    4) Weasel can resolve names when it uses its wireless interface instead of
    its wired ethernet interface.

    5) The contents of /etc/resolv.conf, /etc/nsswitch.conf, and /etc/hosts are
    identical on both weasel and sable.

    6) weasel can ping the default gateway (10.0.40.1) and name servers
    (10.10.10.10 and 10.10.1.10). It just doesn't seem to be able to use the
    name servers to get any names.

    Any ideas as to what the problem could be?

    Regards,
    Tristan

    --
    _
    _V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
    / |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
    (7_\\ http://www.nothingisreal.com/ >< To finish what you

  2. Re: Names not resolving

    In news:22048627.PjrfpC2iqa@polecat.worldsocialism.or g,
    Tristan Miller typed:

    > 6) weasel can ping the default gateway (10.0.40.1) and name servers
    > (10.10.10.10 and 10.10.1.10). It just doesn't seem to be able to use
    > the name servers to get any names.


    Can weasel ping the nameservers by IP addresses? Can it "tcptraceroute
    w.x.y.x 53" to the nameservers? tcptraceroute will tell you where the
    roadblock is (if any) along the route, and if the port is open to weasel.
    What is the result of "/sbin/route -n" and "/sbin/ifconfig eth0" (assuming
    the wired interface is eth0)?

    The above steps are fundamnetal diagnostics for any such problems.



  3. Re: Names not resolving

    In news:6alhtfF37dh8fU1@mid.individual.net,
    ynotssor typed:

    >> 6) weasel can ping the default gateway (10.0.40.1) and name servers
    >> (10.10.10.10 and 10.10.1.10). ...

    >
    > Can weasel ping the nameservers by IP addresses?


    Sorry for the needless question.



  4. Re: Names not resolving

    Greetings.

    In article <6alhtfF37dh8fU1@mid.individual.net>, ynotssor wrote:
    > In news:22048627.PjrfpC2iqa@polecat.worldsocialism.or g,
    > Tristan Miller typed:
    >
    >> 6) weasel can ping the default gateway (10.0.40.1) and name servers
    >> (10.10.10.10 and 10.10.1.10). It just doesn't seem to be able to use
    >> the name servers to get any names.

    >
    > Can weasel ping the nameservers by IP addresses?


    Yes.

    > Can it "tcptraceroute
    > w.x.y.x 53" to the nameservers? tcptraceroute will tell you where the
    > roadblock is (if any) along the route, and if the port is open to weasel.


    11:12 weasel:~ # tcptraceroute 10.10.10.10 53
    Selected device eth0, address 10.0.40.133, port 36290 for outgoing packets
    Tracing the path to 10.10.10.10 on TCP port 53, 30 hops max
    1 10.10.10.10 [closed] 0.827 ms 1.251 ms 1.359 ms

    11:12 weasel:~ # tcptraceroute 10.10.1.10 53
    Selected device eth0, address 10.0.40.133, port 33449 for outgoing packets
    Tracing the path to 10.10.1.10 on TCP port 53, 30 hops max
    1 10.10.1.10 [closed] 0.775 ms 1.349 ms 1.375 ms

    > What is the result of "/sbin/route -n"


    [psy@weasel:~]$ /sbin/route -n
    Kernel IP routing table
    Destination Gateway Genmask Flags Metric Ref Use
    Iface
    10.0.40.0 0.0.0.0 255.255.255.0 U 0 0 0
    eth0
    127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
    0.0.0.0 10.0.40.1 0.0.0.0 UG 0 0 0
    eth0

    > and "/sbin/ifconfig eth0"


    11:44 weasel:/etc # ifconfig -a
    eth0 Link encap:Ethernet HWaddr 00:1E:37:16:AD:FE
    inet addr:10.0.40.133 Bcast:10.0.40.255 Mask:255.255.255.0
    inet6 addr: fe80::21e:37ff:fe16:adfe/64 Scope:Link
    UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
    RX packets:5964 errors:0 dropped:0 overruns:0 frame:0
    TX packets:489 errors:0 dropped:0 overruns:0 carrier:0
    collisions:0 txqueuelen:100
    RX bytes:400929 (391.5 Kb) TX bytes:51943 (50.7 Kb)
    Base address:0x1840 Memory:fe200000-fe220000

    > The above steps are fundamnetal diagnostics for any such problems.


    Thanks for your suggestions. I note that with tcptraceroute, port 53 on
    the nameservers is closed. However, if I try the exact same command while
    connected through eth1 (the wireless network), it says the port is open.
    Any idea why that would be? I would have thought that for some reason,
    the name servers were blocking access from my machine based on the MAC
    address of its ethernet card, except that everything works fine when I
    reboot to Windows XP!

    Is it possible I'm running something on my machine which is blocking
    outbound connections to port 53? If so, how would I find out?

    Regards,
    Tristan

    --
    _
    _V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
    / |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
    (7_\\ http://www.nothingisreal.com/ >< To finish what you

  5. Re: Names not resolving

    On Jun 4, 3:17*am, Tristan Miller
    wrote:

    > Thanks for your suggestions. *I note that with tcptraceroute, port 53 on
    > the nameservers is closed. *However, if I try the exact same command while
    > connected through eth1 (the wireless network), it says the port is open.
    > Any idea why that would be? *I would have thought that for some reason,
    > the name servers were blocking access from my machine based on the MAC
    > address of its ethernet card, except that everything works fine when I
    > reboot to Windows XP!


    It is likely blocking based on the source IP address.

    DS

  6. Re: Names not resolving

    Greetings.

    In article
    , David
    Schwartz wrote:
    > On Jun 4, 3:17*am, Tristan Miller
    > wrote:
    >
    >> Thanks for your suggestions. *I note that with tcptraceroute, port 53 on
    >> the nameservers is closed. *However, if I try the exact same command
    >> while connected through eth1 (the wireless network), it says the port is
    >> open. Any idea why that would be? *I would have thought that for some
    >> reason, the name servers were blocking access from my machine based on
    >> the MAC address of its ethernet card, except that everything works fine
    >> when I reboot to Windows XP!

    >
    > It is likely blocking based on the source IP address.


    Only if DHCP were allocating my machine different IP addresses in GNU/Linux
    and Windows, which I doubt.

    Regards,
    Tristan

    --
    _
    _V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
    / |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
    (7_\\ http://www.nothingisreal.com/ >< To finish what you

  7. Re: Names not resolving

    On Jun 5, 3:04*am, Tristan Miller
    wrote:

    > Only if DHCP were allocating my machine different IP addresses in GNU/Linux
    > and Windows, which I doubt.


    Wasn't this a machine with more than one interface?

    DS

  8. Re: Names not resolving

    Greetings.

    In article
    <78acb2be-4895-4650-a3a9-8a1065442c6a@25g2000hsx.googlegroups.com>, David
    Schwartz wrote:

    > On Jun 5, 3:04*am, Tristan Miller
    > wrote:
    >
    >> Only if DHCP were allocating my machine different IP addresses in
    >> GNU/Linux and Windows, which I doubt.

    >
    > Wasn't this a machine with more than one interface?


    Yes. It has eth0 (wired ethernet) and eth1 (wireless). Both work in
    Windows XP, but in openSUSE 10.3, only eth1 works fully. eth0 connects to
    the network but does not seem to be able to use the name server to resolve
    names.

    Regards,
    Tristan

    --
    _
    _V.-o Tristan Miller [en,(fr,de,ia)] >< Space is limited
    / |`-' -=-=-=-=-=-=-=-=-=-=-=-=-=-=-= <> In a haiku, so it's hard
    (7_\\ http://www.nothingisreal.com/ >< To finish what you

  9. Re: Names not resolving

    On Jun 5, 6:20*am, Tristan Miller
    wrote:

    > >> Only if DHCP were allocating my machine different IP addresses in
    > >> GNU/Linux and Windows, which I doubt.

    >
    > > Wasn't this a machine with more than one interface?

    >
    > Yes. *It has eth0 (wired ethernet) and eth1 (wireless). *Both work in
    > Windows XP, but in openSUSE 10.3, only eth1 works fully. *eth0 connects to
    > the network but does not seem to be able to use the name server to resolve
    > names.


    Right, so DHCP is not the only way it could use a different address
    with Linux as it does with XP. More than one interface means more than
    one IP, and the way you choose which to use as a source address for a
    particular request can vary from OS to OS.

    DS

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