>>>>> "Tom" == Tom Sharples <[email protected]> writes:
Tom> Hello all, We have several installations of embedded wireless Tom> routers (running slack on a 2.4 kernel) in which the gateway Tom> router_1 uses a Verizon 3G USB modem (ppp0) as its connection to Tom> the outside world, and one or more downstream router_2 have Tom> 5.8Ghz wireless links to router_1, and thus route traffic to the Tom> outside world through the same ppp0 3G connection. Tom> Verizon has a habit of constantly changing the ppp0 IP address Tom> often sometime several time per hour. I would like to figure out Tom> a way that the downstream router_2 can be made aware of that ppp0 Tom> address change at router_1 within a minute or two of it Tom> happening. The obvious way seemed to be running a cronjob Tom> traceroute from the router_2 to a known outside IP, with a limit Tom> of two of three hops, and grepping the first public IP and Tom> looking for the change. However, for some reason that shows the Tom> Verizon gateway router on their tower as the first public IP Tom> rather that the locally assigned ppp0 public IP address. Any Tom> suggestions for how to determine that ppp0 IP using standard Tom> tools and pref. without writing e.g. inter-router communications Tom> scripts etc. would be welcome. Tom> verizon_tower------------------[3G_modem(ppp0)]-[router_1]---------------[5.8Ghz_link]----------------[router_2] Traceroute won't work because you want the outward facing address on the gateway device, and traceroute will give you the inward facing address. This was discussed a month or so ago. There are dynamic dns scripts for asking an external service what your public ip addr looks like. whatsmyip.org has an API for doing this, though they ask you to be gentle. Any machine you have with a publicly accessable interface could do the same thing. They'll see router_1's public ipaddr no matter how often verizon changes it. -- Russell Senior, President [email protected] _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
