Problems with DHCP?

[rideDPU]

I figured I would try this forum first due to its generally great advice and friendly, helpful members.

Recently, when I plug into my ethernet connection in my fraternity house, I am instantly assigned an IP address of 192.xxx.xxx.xxx -- instead of something along the lines of 163.127.xxx.xxx -- an IP address from the University network. As soon as I do a little IP release/renew shuffle, everything comes up fine and I have a connection to the outside world (ie. an IP address beginning with 163) Needless to say, its pretty frustrating! Do any of you have an ideas as to where I may be able to find a solution? I've tried Google, but frankly, I don't know what to search for...

Thanks,
Mark

[Kyocera]

It sounds like they have two devices assigning IP address, the 192.168.XXX is probably a linksys or equivalent router with DHCP enabled, if the full IP address is something like 192.168.1.X I'd be willing to bet it is a linksys or d-link or something, the second IP address sounds like a server issuing you the official IP to access the network, Internet etc.
This is a sticky situation, however, if you want to you should be able to disable DHCP in the first (192.168.etc.etc.) by typing 192.168.1.1 in the address portion of your web browser, this may pull up the web browser to the router, navigate to the DHCP page and you will see DHCP enable or disable check disable and restart the web browser, this device will no longer be issuing IP addresses. The default password to access the full functionality is administrator, type this if promted for a password. If this does not work they have enabled security and you will not be able to access the device.

Another possibility is to do an ipconfig /all on your system when you finally get the address you need to access the internet/network, write down the ip information, subnet, dns, etc. Some DHCP servers will issue you the same IP address over and over, if the time between sessions is not to long. Type this information into the TCP/IP properties on the appropriate network connection on your machine, this will now be a static ip.

Edit: MadeInJapan is correct on the password issue, sometimes in the user block type admin, leave password blank, click OK, on linksys when the log in screen pops up look in the upper left corner for the alphanumeric model number, type that in the user and leave the password blank, or admin or administrator.

[MadeInJapan]

"Administrator" is sometimes the password...with D-link I often see "Admin" and with others, sometimes, "public." It is hard to second guess these. I found this series from a Blog very interesting. You can try something like this. I'll paste it below:

I switch IP addresses constantly every day with configuring Radios,
>> Connecting to Access Points on different Routers, and doing customer
>> installs and setting up home routers. I have created several batch files
>> that sit on my desktop, and then i can just double click on an icon to
>> chenge my address. I have renamed my cards to "Orinoco" "Prism" and
> "3Com"
>>
>> Below are some instructions I put together for some peers, and I thought I would share it with the list.

>> You can rename your adapter to something like I use.
>>
>> In network connections window, you can right click on the connection and choose rename
>>
>> To verify the name, open up a dos window and type the following
>>
>> netsh interface ip show config
>>
>> It will show you your settings and the name of the adapter(s)
>>
>> Here is a batch file I have called prism dhcp.bat
>>
>> netsh interface ip show config
>> netsh int ip set address name="prism" source=dhcp
>> ipconfig /all
>> pause
>>
>> NOTE:
>> I put the pause in there so I can see the results of the ipconfig command
>>
>> here is one for setting a static address
>> I called it prism 1.173.bat
>>
>> netsh interface ip show config
>> netsh int ip set address name="prism" source=static 192.168.1.173
>> 255.255.255.0 192.168.1.1 1
>> ipconfig /all
>> pause
>>
>> These batch files are saved on the desktop, and I can just double click
on them to change the address as needed.

[rideDPU]

Thanks all for the help...I've been down in the network closet and its an assortment of Cisco and HP switches tied into the rest of campus via a fiber channel...anyone know the "default" info there? I know the hardware is a bit more serious than the average Best Buy special, but no one here knows any sort of login info...

Mark

[bhtooefr]

Switches? Don't bother, that's not the problem. The PROBLEM is consumer grade crap, not the uni kit.

It's most likely a rouge WiFi access point.

(FWIW, we have a Linksys WRT54G that decided randomly to drop out of AP mode into router mode, and it hijacks the entire DHCP system on our school's network.)

Default on the D-Link DI-524 is admin/1234.

Default on the Belkin F5D7230-4 (IIRC) is admin with NO password.

A friend sent me a list of default passwords for a bunch of devices, but they're on the dead HDD. I *might* be able to recover that list. If not, I'll ask about it.

[Kyocera]

The original post is referencing a wired network connection.

I would also suggest upgrading the firmware on your schools WRt54g or maybe replacing it. I have found that Belkin is on par with linksys and in some cases has more software functionality than Linksys.

[bhtooefr]

Ditto here, as well. The wireless router was hijacking the DHCP.

Looking at it, it almost looks like there *IS* no AP mode.

And, yes, I was going to do a firmware flash.

[rideDPU]

I don't have a wireless router plugged in. Once this funny behavior started, my WRT54 couldn't get a connection so I just unplugged it. I also made sure no one else had a router plugged in.

EDIT: sorry kyocera, I didn't realize you were replying to bhtooefr...

Mark

[Kyocera]

Mark, you can take your laptop to the network closet find an open port on the HP, plug a short cable from your laptop directly in to the router and see what IP address you get, open your web browser and type the first three octets exactly as they appear in your IP address make the last octet 1, this should pull up the web function of the router, now like I said before the one you really want to disable dhcp in is the 192.168 etc.
Whichever router you find assigning this IP address, search the web for a service manual for that particular model this will get you the password set at the factory for this device.

This being said, I have a lot of customers who are set up with DSL with a similar configuration, their PC's are plugged into a router issuing several or more private IP's (192.168 etc) and use one IP from their ISP which is a public IP. Your 163.XXX. would be the public IP. There may be a reason network is set up this way. On the other hand they may have just needed to expand the network threw on another router and forgot to disable DHCP.

[rideDPU]

Kyocera,
Thanks so much for all the help. I have a feeling that another router was just "tacked" on...

Mark

[rideDPU]

OK, I found the offending D-Link 524 (thanks for the tip Kyocera) -- and tale between my legs for saying that there weren't any more wireless routers on the net.
Can anyone point me toward a good resource online for figuring out how to do some network setup? I don't want to have to rely on all of the collective hand-holding here (though I do appreciate it!). Time to figure out how to get the d-link to act as just an AP since when I connect to it, I can't get an IP address with the DHCP turned off...

Thanks again,
Mark

[Kyocera]

Glad you got that worked out! A good bit of detective work.

As far as networking that device, the manual that came with it is a good place to start, when I first started networking I used the "for Dummies"
books which are a great place to start, there are a lot of good tutorials on line as well, you may have to dig a little but should be able to get close to what you need. Microsoft has a lot of good info on their site, newsgroups, tutorials etc. Most companies allow downloads of their manuals and they are full of the basic information for networking.

If you connect to the device or any of these small type routers wireless or not they are normally defaulted for DHCP, once it assigns your system an IP address do an ipconfig, see what address it has assigned you, pull up your web browser and type in the XXX.XXX.XXX.1 (fill in the X's) and you will be able to do all your device configurations from there. Most wireless devices allow you to change from Ad Hoc to Infrastructure, ad hoc being a peer to peer type set up.

[bhtooefr]

I think it'd be set up in Infrastructure mode already, Kyocera.

He wants it set up in ACCESS POINT mode, so that it's a dumb "WiFi forwarder", if you will - basically, a WiFi radio strapped to an Ethernet connection.

I set up a DI-524 not too long ago, but forget where the AP setting is. IIRC, it DID have one, though. Check under Setup>Wireless... (Setup>Wizard will be where it opens to - Wireless will be on the left.)

[Kyocera]

Yeah, you are correct all the ones I have set up default to infrastructure. I've set up a couple of the USB's that look like a highlighter pen, those are so cool looking.