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Peculiar IP address


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#1 hedera

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Posted 11 July 2009 - 10:11 PM

I've been troubleshooting a small network belonging to a local nonprofit. They use a LinkSys BEFSX41 wireless VPN router; they have a single computer in the office (Win XP Pro, don't know the patch level), and the router is used by volunteers who wander in with laptops, and also by the organization's officers who use the VPN to connect the office computer and synch their local copies of an Access database with the master copy on the office computer. (I didn't set this up!) Since the office router connects to the Internet by a PPoE connection, we use DynDNS to connect to the router using a dedicated hostname. The LinkSys router is certified to support DynDNS, and usually we don't have to mess with it.

Recently we lost the ability to connect via VPN. I've established that our ISP did change our IP and for some reason DynDNS didn't pick it up; but for awhile we thought something might be wrong with the router. As a result, I suggested that one of the officers, who was in the office, should "reboot" the router; I actually meant "unplug and plug back in", but he heard "reset to factory default." So we spent today reconfiguring the router (fortunately we have the settings documented), but now I'm seeing something odd. The routing table should show all the computers on the network. The office computer should be 192.168.23.101 (yes, we use a nonstandard network; no, I didn't set it up); that's supposed to be it's static IP, and the firewall rules that allow the VPN connection all link to that IP.

What I see on the network, though, is 192.168.23.0! If this is real, of course, it explains why the VPN won't work. But, how can it be real? I didn't think IP addresses ending in zero were even usable - I know you have problems with addresses ending in 1. I haven't been able to get into the office myself, and won't be able to until Monday, but the office computer has Internet access; we just can't VPN to it. Has anyone ever seen this, and is there anything I can do about it? The LinkSys interface doesn't allow me to assign static IPs to network computers.

Oh, and DynDNS is now picking up the IP address changes again.

Confused,

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#2 CaveDweller2

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Posted 11 July 2009 - 11:50 PM

What is the subnet mask? And what on the network got that IP address?

Hope this helps thumbup.gif

Associate in Applied Science - Network Systems Management - Trident Technical College


#3 hedera

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Posted 12 July 2009 - 01:07 PM

The subnet mask is 255.255.255.0 - I'm not sure what on the network got that address.

I'm not a network expert but I've played with a number of networks, and I can't recall seeing what amounts to the subnet address on a routing table! For the record here is the routing table, which I copied and pasted into the notes I'm taking on this:

Destination LAN IP Subnet Mask Default Gateway Hop Count Interface
0.0.0.0 0.0.0.0 70.231.255.25 1 WAN
70.231.252.33 255.255.255.255 0.0.0.0 1 WAN
192.168.23.0 255.255.255.0 0.0.0.0 1 LAN

The 70.231 address is the current Internet address of the router. The router should have an internal address of 192.168.23.1 - that's what I configured; but it doesn't show. And the table should show a static IP (the office computer) of 192.168.23.101, which isn't there either. The office computer, by the way, is connected via Ethernet, not wireless.

The "routing table" shows on the LinkSys Advanced Routing tab under Setup, and the help files don't clearly explain what it represents.

Until I get into the office, I can't rule out the possibility that one of the officers may have messed with the office computer's network configuration... we have one who's broken stuff before.




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