Simple Route Question - Networking

This is a discussion on Simple Route Question - Networking ; I've worked on Linux and done some work with networking, but that's been just basic setup stuff. For now, I have a net on 172.16.xxx.xxx and I will need to be able to connect to a Linksys router I'm working ...

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  1. Simple Route Question

    I've worked on Linux and done some work with networking, but that's been
    just basic setup stuff. For now, I have a net on 172.16.xxx.xxx and I will
    need to be able to connect to a Linksys router I'm working with for a while
    that I'll be putting OpenWRT on. While doing this, I need to address the
    router in its default 192.168.1.1 address from my workstation.

    I used:

    route add -host 192.168.1.1 eth0

    then typed "route" and got this:

    Kernel IP routing table
    Destination Gateway Genmask Flags Metric Ref Use
    Iface
    192.168.1.1 * 255.255.255.255 UH 0 0 0 eth0
    172.16.7.0 * 255.255.255.0 U 0 0 0 eth0
    link-local * 255.255.0.0 U 1000 0 0 eth0
    default loc.fw.lan 0.0.0.0 UG 0 0 0 eth0

    When I try to reach the router by the web interface, there's no response and
    lynx is "Unable to connect to remote host." I've tried adding "dev"
    before "eth0" when I set up the route, but it doesn't work.

    I've been looking for a routing tutorial, but all the ones I find use
    iproute or iproute2 and the man page for route gives examples for adding
    nets, but no specific examples of adding hosts, so while I'm using what the
    few references I can find seem to say to do, I figure I've got to be doing
    something wrong and I can't find a good resource on the net to tell me what
    I need to change.

    What am I doing wrong?

    Thanks!

    Hal

  2. Re: Simple Route Question

    On Jul 27, 4:53 pm, Hal Vaughan wrote:
    > I've worked on Linux and done some work with networking, but that's been
    > just basic setup stuff. For now, I have a net on 172.16.xxx.xxx and I will
    > need to be able to connect to a Linksys router I'm working with for a while
    > that I'll be putting OpenWRT on. While doing this, I need to address the
    > router in its default 192.168.1.1 address from my workstation.
    >
    > I used:
    >
    > route add -host 192.168.1.1 eth0
    >
    > then typed "route" and got this:
    >
    > Kernel IP routing table
    > Destination Gateway Genmask Flags Metric Ref Use
    > Iface
    > 192.168.1.1 * 255.255.255.255 UH 0 0 0 eth0
    > 172.16.7.0 * 255.255.255.0 U 0 0 0 eth0
    > link-local * 255.255.0.0 U 1000 0 0 eth0
    > default loc.fw.lan 0.0.0.0 UG 0 0 0 eth0
    >
    > When I try to reach the router by the web interface, there's no response and
    > lynx is "Unable to connect to remote host." I've tried adding "dev"
    > before "eth0" when I set up the route, but it doesn't work.
    >
    > I've been looking for a routing tutorial, but all the ones I find use
    > iproute or iproute2 and the man page for route gives examples for adding
    > nets, but no specific examples of adding hosts, so while I'm using what the
    > few references I can find seem to say to do, I figure I've got to be doing
    > something wrong and I can't find a good resource on the net to tell me what
    > I need to change.
    >
    > What am I doing wrong?
    >
    > Thanks!
    >
    > Hal


    I don't quite understand what you're trying to do?

    Are you trying to add a default gateway?

    route add default gw 192.168.1.1 (optionally you COULD add: route
    add default gw 192.168.1.1 dev eth0 )



  3. Re: Simple Route Question

    Hal Vaughan wrote:
    >I've worked on Linux and done some work with networking, but that's been
    >just basic setup stuff. For now, I have a net on 172.16.xxx.xxx and I will
    >need to be able to connect to a Linksys router I'm working with for a while
    >that I'll be putting OpenWRT on. While doing this, I need to address the
    >router in its default 192.168.1.1 address from my workstation.


    Okay, I'm assuming this is a Linksys WRT54G wireless
    router, probably a Version 2??? (The following
    discussion applies to any WRT54G.)

    >I used:
    >
    >route add -host 192.168.1.1 eth0


    Okay, that looks good!

    >then typed "route" and got this:
    >
    >Kernel IP routing table
    >Destination Gateway Genmask Flags Metric Ref Use
    >Iface
    >192.168.1.1 * 255.255.255.255 UH 0 0 0 eth0
    >172.16.7.0 * 255.255.255.0 U 0 0 0 eth0
    >link-local * 255.255.0.0 U 1000 0 0 eth0
    >default loc.fw.lan 0.0.0.0 UG 0 0 0 eth0


    Yep, you now have a route from this host *to* the
    router, via eth0.

    But alas, the router's route table does not provide a
    way to get back, via the LAN ports, to a host with an
    address in the 172.16.x.x range.

    This is a (somewhat obnoxious) result of the router
    being designed (and the documentation written) to work
    with home users of Windows. I.e., it defaults to what
    will work on the simplest Windows system, and they don't
    tell you what that is.

    The router defaults to 192.168.1.1, *and* has its DHCP
    server enabled... with a route table that knows about
    the IP addresses which the DHCP server can assign, and
    nothing else. There is no default to the LAN ports
    (there might be to the WAN port, I don't remember... but
    it would be worthless too because it cannot access the
    HTTP server).

    So, there are two possible tricks you can use to access
    the router. One is to use DHCP to get an Ethernet
    interface configured to match the router. You can do
    that with a laptop, using the only Ethernet port or
    using a spare on a desktop that has two or more, or
    whatever.

    dhcpcd -d eth0

    Will configure eth0 via DHCP. You just want to be sure
    that the *only* DHCP server on that LAN segment is that
    particular router

    The other way is to give a static IP address in the right
    range to an Ethernet interface. This can work on a
    LAN segment that does have a DHCP server on it.

    And (with either static route or with a DHCP server) you
    don't actually need a spare unused interface!

    ifconfig eth0:1 192.168.1.100

    will add the IP address 192.168.1.100 to eth0,
    regardless of what has already been assigned to it (as
    long as it wasn't to eth0:1). To disable it after you
    are done,

    ifconfig eth0:1 192.168.1.100 down

    Just be advised that I don't remember exactly what the
    range of IP addresses that are being routed actually
    are! I'm sure that it is in the 192.168.1.x subnet, and
    it seems like it is a range of 100 addresses, but it
    might be 50. That makes the above 192.168.1.100 a good
    guess at a place to start, but it is only a guess.

    >When I try to reach the router by the web interface, there's no response and
    >lynx is "Unable to connect to remote host." I've tried adding "dev"
    >before "eth0" when I set up the route, but it doesn't work.
    >
    >I've been looking for a routing tutorial, but all the ones I find use
    >iproute or iproute2 and the man page for route gives examples for adding
    >nets, but no specific examples of adding hosts, so while I'm using what the
    >few references I can find seem to say to do, I figure I've got to be doing
    >something wrong and I can't find a good resource on the net to tell me what
    >I need to change.
    >
    >What am I doing wrong?


    You're doing nothing wrong... you just need to continue
    with a few more of the right things!

    --
    Floyd L. Davidson
    Ukpeagvik (Barrow, Alaska) floyd@apaflo.com

  4. Re: Simple Route Question

    Floyd L. Davidson wrote:

    > Hal Vaughan wrote:
    >>I've worked on Linux and done some work with networking, but that's been
    >>just basic setup stuff. For now, I have a net on 172.16.xxx.xxx and I
    >>will need to be able to connect to a Linksys router I'm working with for a
    >>while
    >>that I'll be putting OpenWRT on. While doing this, I need to address the
    >>router in its default 192.168.1.1 address from my workstation.

    >
    > Okay, I'm assuming this is a Linksys WRT54G wireless
    > router, probably a Version 2??? (The following
    > discussion applies to any WRT54G.)


    Yes, it is. I didn't want to go into that level of detail, but I guess
    that's what most people are working with on something like this.

    >>I used:
    >>
    >>route add -host 192.168.1.1 eth0

    >
    > Okay, that looks good!
    >
    >>then typed "route" and got this:
    >>
    >>Kernel IP routing table
    >>Destination Gateway Genmask Flags Metric Ref Use
    >>Iface
    >>192.168.1.1 * 255.255.255.255 UH 0 0 0
    >>eth0
    >>172.16.7.0 * 255.255.255.0 U 0 0 0
    >>eth0
    >>link-local * 255.255.0.0 U 1000 0 0
    >>eth0
    >>default loc.fw.lan 0.0.0.0 UG 0 0 0
    >>eth0

    >
    > Yep, you now have a route from this host *to* the
    > router, via eth0.
    >
    > But alas, the router's route table does not provide a
    > way to get back, via the LAN ports, to a host with an
    > address in the 172.16.x.x range.


    I see. So what's on the Linux box is right, it's the router with the
    problem.

    > This is a (somewhat obnoxious) result of the router
    > being designed (and the documentation written) to work
    > with home users of Windows. I.e., it defaults to what
    > will work on the simplest Windows system, and they don't
    > tell you what that is.


    Yes. I originally had a new WRT54GS and that was worse. I didn't know the
    default IP address and used the setup disk on my one Windows system and it
    hosed the networking settings. I had to change all the settings back to
    get the computer to work on my network again.

    > The router defaults to 192.168.1.1, *and* has its DHCP
    > server enabled... with a route table that knows about
    > the IP addresses which the DHCP server can assign, and
    > nothing else. There is no default to the LAN ports
    > (there might be to the WAN port, I don't remember... but
    > it would be worthless too because it cannot access the
    > HTTP server).


    The WAN can access the HTTP server, but not until it's configured to do
    that. I was able to change over to do it eventually, but I've flashed the
    firmware now and I'm having a similar problem again, but I'm getting help
    in configuring the firewall on the OpenWRT site.

    > So, there are two possible tricks you can use to access
    > the router. One is to use DHCP to get an Ethernet
    > interface configured to match the router. You can do
    > that with a laptop, using the only Ethernet port or
    > using a spare on a desktop that has two or more, or
    > whatever.
    >
    > dhcpcd -d eth0


    I ended up just having to pull plugs on my Ethernet switch and taking the
    only system with a cable long enough to connect to another router, which
    was my Windows system.

    ....
    >>What am I doing wrong?

    >
    > You're doing nothing wrong... you just need to continue
    > with a few more of the right things!


    Thanks for the help! Once I understood the issue and that it was on the
    router's end, I pulled the cable out and hooked up my Windows system, as I
    said. It solved that problem and was a big help!

    Hal


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