On Dec 10, 2010, at 3:53 PM, Levan, Jerry wrote:

> Hi,
> 
> More stuff I am try to get a hold on...
> 
> When the internet was a bit younger I had a linksys router and I
>   wrote a bit of code that fetched the (web) page of the router that
>   contained the routers external address.
> 
>   If the address changed I invoked mail and sent the address to an
>   account I had at work.
> 
>   I could then ssh to my home computer...

Well there's been DynDNS that's been doing this for you since longer than 
linksys routers...

> Time passed...
>   I now have an airport extreme base station ( dual band ). No
>   web interface here!

It may surprise you what may actually use HTTP as a transport. 

> ( I guess apple did not want to make the AEBS
>   easy for anyone to use ).
> 
> Using the airport utility I see a router address of 76.177.12.46
> 
> using snmpwalk I find:

Before you keep rolling without identifying your real problem why don't I just 
equally roll in with a simple solution for a trivial non-problem: dyndns. 

> bash-3.2# snmpwalk -c public router | grep 76.177.12.46
> IP-MIB::ipAdEntAddr.76.177.12.46 = IpAddress: 76.177.12.46
> IP-MIB::ipAdEntIfIndex.76.177.12.46 = INTEGER: 16
> IP-MIB::ipAdEntNetMask.76.177.12.46 = IpAddress: 255.255.224.0
> IP-MIB::ipAdEntBcastAddr.76.177.12.46 = INTEGER: 1
> RFC1213-MIB::ipRouteDest.76.177.12.46 = IpAddress: 76.177.12.46
> RFC1213-MIB::ipRouteIfIndex.76.177.12.46 = INTEGER: 4
> RFC1213-MIB::ipRouteMetric1.76.177.12.46 = INTEGER: 1
> RFC1213-MIB::ipRouteMetric2.76.177.12.46 = INTEGER: 0
> RFC1213-MIB::ipRouteMetric3.76.177.12.46 = INTEGER: 0
> RFC1213-MIB::ipRouteMetric4.76.177.12.46 = INTEGER: 0
> RFC1213-MIB::ipRouteNextHop.76.177.0.0 = IpAddress: 76.177.12.46
> RFC1213-MIB::ipRouteNextHop.76.177.0.1 = IpAddress: 76.177.12.46
> RFC1213-MIB::ipRouteNextHop.76.177.12.46 = IpAddress: 127.0.0.1
> RFC1213-MIB::ipRouteType.76.177.12.46 = INTEGER: indirect(4)
> RFC1213-MIB::ipRouteProto.76.177.12.46 = INTEGER: local(2)
> RFC1213-MIB::ipRouteMask.76.177.12.46 = IpAddress: 255.255.255.255
> RFC1213-MIB::ipRouteMetric5.76.177.12.46 = INTEGER: 33172
> RFC1213-MIB::ipRouteInfo.76.177.12.46 = OID: SNMPv2-SMI::zeroDotZero
> UDP-MIB::udpLocalAddress.76.177.12.46.500 = IpAddress: 76.177.12.46
> UDP-MIB::udpLocalAddress.76.177.12.46.4500 = IpAddress: 76.177.12.46
> UDP-MIB::udpLocalPort.76.177.12.46.500 = INTEGER: 500
> UDP-MIB::udpLocalPort.76.177.12.46.4500 = INTEGER: 4500
> 
> So the router address is in there but it is not clear to me how to extract
> the rascal and be sure that I have the right address ( I had hoped to use
> snmpcmd but I can't find the magical incantation that will fetch the right 
> object.
> ( Everything I know about snmp comes from about 30 minutes of browsing man 
> pages...)
> 
> Note that there are about 4 different IPs tagged with ipAdEntAddr, the grep 
> just
> fished one of them out.
> 
> Can the resident snmp experts hit me with a clue stick?

How about you just define a real function you're trying to achieve: being able 
to access your dynamically assigned public IP address assigned to your NAT'ed 
network remotely. And you want to know about it and maybe if it changes. 

Over the years the InterWebs have developed a way to determine or announce an 
IP address, they called it DNS. Of course the problem for all those with an IP 
address that kept changing was to noticed that it changed and be able to switch 
the IP address to the new one when the dynamic address changed. So DynDNS - a 
free service - came about, along with tools/plugins/apps that allow for the 
whole notification of changes thingie to be dealt with. 

Have you considered why this won't work to resolve what may be your real 
problem here?

In other words perhaps you're going about this in the wrong way?

-d

------------------------------------------------------------------------
Dan Shoop
[email protected]
GoogleVoice: 1-646-402-5293
aim: iWiring
twitter: @colonelmode



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