Two NICs in different SubNets - Network

This is a discussion on Two NICs in different SubNets - Network ; My connection to the outside world is via a WLAN-Router(, which also serves as a DHCP-, & DNS-Server) and usually all network traffic runs via wireless cards. However, I wanted to connect two of my machines directly via cable NICs ...

+ Reply to Thread
Results 1 to 2 of 2

Thread: Two NICs in different SubNets

  1. Two NICs in different SubNets

    My connection to the outside world is via a WLAN-Router(, which also
    serves as a DHCP-, & DNS-Server) and usually all network traffic runs
    via wireless cards. However, I wanted to connect two of my machines
    directly via cable NICs (faster & takes load of the WLAN).
    The WLAN traffic runs in the 10.0.0.0 network (WLAN-Router default
    factory setting) with 10.0.0.138 beeing the Router/Gateway and
    DHCP-Clients having IPs in the range 10.0.0.151 to 200. For the cable
    connection the NICs have static IPs in the 192.168.0.0 network, namely
    192.168.0.9 (LinUx 2.4.26) & 192.168.0.11 (WinXP + CygWin). Thus the two
    machines are connected via WLAN as well as cable. Of course they have
    different names in the different networks. After I set up everything for
    the cable connection, the WLAN still runs as it always did. I can
    perfectly ping via the cable in both directions, thus the physical
    connection is up and working. However, so far I had no success in
    getting any other service to connect, as for example SAMBA (LinUx is the
    server and it works via WLAN), FTP (neither direction), SSH (neither
    direction) or the like. The only exceptions are X11-applications, which
    I start on the LinUx box to actually open on the WinXP machine (of
    course I have to have CygWin running there with the appropriate "xhost"
    setting).
    The routing tables look fine (see below), as they should since PING works.



    Kernel IP routing table of machine 192.168.0.9 (LinUx 2.4.26)
    Destination Gateway Genmask Flags Metric Ref Use
    Iface
    10.0.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
    192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
    169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth1
    127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo
    0.0.0.0 10.0.0.138 0.0.0.0 UG 0 0 0 eth1


    routing table of machine 192.168.0.11 (WinXP + CygWin)
    ================================================== ========================
    Interface List
    0x1 ........................... MS TCP Loopback interface
    0x2 ...00 06 29 95 5e f1 ...... IBM 10/100 EtherJet CardBus Adapter #2 -
    Packet
    Scheduler Miniport
    0x10004 ...00 02 2d b5 f2 10 ...... Wireless PC Card Model 0104 - Packet
    Schedul
    er Miniport
    ================================================== =========================
    ================================================== =========================
    Active Routes:
    Network Destination Netmask Gateway Interface Metric
    0.0.0.0 0.0.0.0 10.0.0.138 10.0.0.152 30
    10.0.0.0 255.255.255.0 10.0.0.152 10.0.0.152 30
    10.0.0.152 255.255.255.255 127.0.0.1 127.0.0.1 30
    10.255.255.255 255.255.255.255 10.0.0.152 10.0.0.152 30
    127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
    192.168.0.0 255.255.255.0 192.168.0.11 192.168.0.11 20
    192.168.0.11 255.255.255.255 127.0.0.1 127.0.0.1 20
    192.168.0.255 255.255.255.255 192.168.0.11 192.168.0.11 20
    224.0.0.0 240.0.0.0 10.0.0.152 10.0.0.152 30
    224.0.0.0 240.0.0.0 192.168.0.11 192.168.0.11 20
    255.255.255.255 255.255.255.255 10.0.0.152 10.0.0.152 1
    255.255.255.255 255.255.255.255 192.168.0.11 192.168.0.11 1
    Default Gateway: 10.0.0.138
    ================================================== =========================
    Persistent Routes:
    None


    Any network guru out there with reasonable suggestions?

    Jogy

    ================================================== =============================
    Dr. Joachim A. Stwe + Duindoornstr. 1 + NL-2211PH Noordwijkerhout
    ================================================== =============================

  2. Re: Two NICs in different SubNets

    In the Usenet newsgroup redhat.networking.general, in article
    <433d287f$0$2887$ba620dc5@text.nova.planet.nl>, Joachim A. Stuewe wrote:

    Nice obscure news groups your picked. Next time, try the regular group
    comp.os.linux.networking.

    >My connection to the outside world is via a WLAN-Router(, which also
    >serves as a DHCP-, & DNS-Server) and usually all network traffic runs
    >via wireless cards. However, I wanted to connect two of my machines
    >directly via cable NICs (faster & takes load of the WLAN).


    and is a lot more secure.

    >The WLAN traffic runs in the 10.0.0.0 network


    >For the cable connection the NICs have static IPs in the 192.168.0.0
    >network, namely 192.168.0.9 (LinUx 2.4.26) & 192.168.0.11 (WinXP +
    >CygWin). Thus the two machines are connected via WLAN as well as cable.


    OK - some of our systems have three networks; normal, admin, and backup.
    Root is only allowed to connect over the admin net, and the backup net
    is used to connect the servers to the system with the tape drives. We do
    this for security as well as bandwidth reasons.

    >Of course they have different names in the different networks.


    Good - that's all that is needed, other than seeing that the names and
    addresses get resolved - either by dinking with the name server, or
    entering them into both 'hosts' files.

    >After I set up everything for the cable connection, the WLAN still runs
    >as it always did. I can perfectly ping via the cable in both directions,
    >thus the physical connection is up and working.


    Great!

    >However, so far I had no success in getting any other service to connect,
    >as for example SAMBA (LinUx is the server and it works via WLAN), FTP
    >(neither direction), SSH (neither direction) or the like.


    The problem is that you have these systems trying to talk to each other
    using the WLAN names/addresses (which also may be a windoze default - I
    don't use windoze or Samba). What happens if you try to 'ftp 192.168.0.9'
    or 'ftp hostname_for_192.168.0.9' and similar. This should work assuming
    you don't have a on-system firewall problem.

    Windoze is designed to work any way it can, no matter how bad the admin
    screws things up. It does this with a lot of self discovery traffic,
    which has security implications, but that's not microsoft's problem as
    they state in their EULA. What you may see is that windoze (and Samba)
    use discovery packets to find other systems, and consequently assume
    that duplicate routes are irrelevant (and ignored), and configuration
    data (such as hosts file) that don't match their discovery are assumed
    to be a result of a stupid admin, and they can safely ignore those as well.
    Given the average skill of a windoze administrator, this often is a very
    good concept - but it falls apart when conditions are more complex than
    microsoft envisions. Multiple paths is one of those "it can't happen"
    conditions as far as they are concerned. There should be a "I know what
    I'm doing - stop trying to help me" switch in there, but as I don't do
    winodze, I can't say where.

    Old guy

+ Reply to Thread