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  1. #1

    access host on another subnet

    I've recently done some reconfigurations of my home network in hopes of improving a reception problem that cropped up. I've applied a somewhat complicated solution which seems to be working well in terms of giving the host in question a better and more reliable connection to my LAN and thus to the internet. So, though access from that host to other hosts on my LAN (and to the internet, as I mentioned) is working well, I am now unable to access that host from other hosts on my LAN. I suspect the problem has to do with the fact that I've used a wifi device that puts that host on a different subnet than the subnet of the LAN the other hosts are on.

    Here's a further description of my home network. I have a wrt54g that functions as my main router/gateway: it's been flashed with dd-wrt. The base address for the subnet it creates is I have a second wrt54g that is similarly flashed and is set up in bridge mode: it's function is to get the wifi signal to the side of the apartment from which my office is almost visible, and from there, down to my office. It is the host in the office where I've been having some connectivity issues, and those issues are related to physical layout: the office is in a different wing of the apt building in which I live and, while only about 50 feet away, it is on the 1st floor, while the apt is on the 4 th floor. There is also a roof and some masonry that keeps me from getting a direct line of sight from my apt window to where the office is located.

    I've struggled with making the wifi connection to that office computer work, with mixed results. I finally decided to try out a solution that involves hooking that host, via cat5 cable, to a router (fonera) that's also flashed with dd-wrt and is configured in client mode (directions for configuring the fonera can be found at the dd-wrt wiki in an article entitled LaFonera_Software_Client-Mode--this stupid system won't let me post the actual url). The way this could help address the problem is that, with a long enough cat5 cable, I can move around the fonera to various places where the signal is better. And, as I've said, this solution does seem to give me a better and more reliable connection to my LAN from the host where I had been having problems.

    The new problem that solution has introduced, however, is that, while I am able to access hosts on my apartment LAN and access the internet from the office host more reliably than previously, I cannot now connect to that office host from my LAN. I cannot ping that host, for example, either by hostname or by IP. As I've alluded to above, I think this is because of the way the fonera-in-client-mode is set up: it puts that host on a different subnet (base address I'm guessing that, because my main gateway/router, doesn't "know" about the existence of this subnet (which is established and distributed by the fonera), it doesn't know how to route traffic from my main LAN to that subnet.

    So, I'm looking for solutions now to that new problem: how to access, from my main LAN, that office host on the new fonera subnet. I have been very regularly ssh'ing into that host, and I need to keep ssh sessions to it available.

    In the way of additional details, I might mention that the fonera does get assigned an address within the subnet of my main LAN (base address that is its "WAN address." I can ping it, either by IP or by host name, from my main LAN. Also, when I ssh from the office host to a host on my main LAN, ssh shows the connection coming from the fonera's host name, not from the office's host name. I have disabled the firewall on the fonera, have set it to do port forwarding (22) to the office host, have tried putting the office host in the fonera's DMZ. But so far I've found no way to ping or establish an ssh session from my main LAN to the office host.

    Any input and/or pointers on how I can access that office host from hosts on my main LAN?


  2. #2
    I have a workaround for this problem. I finally understood that attempts I had been making to use the fonera as a go-between (via port forwarding) for my ssh sessions had not been working because I had disabled the firewall on the fonera. Now that I've re-enabled ther firewall port forwarding works. So I've set up the fonera so that it forwards port 1234 to port 22 on the host that's connected to it and now, when I issue "ssh -p 1234 fonera" it allows me to ssh into the host machine connected to fonera. It's a bit kludgy and it seems to me there must be a more elegant solution that would allow me to ssh to the host on the fonera's subnet, but the solution I've found will get me by for now.


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