What's up guys. This may have a simple solution, but I'm stumped... and pretty confused.

I'm setting up Debian on the free space of a new laptop, the first try goes great. But after finalizing the installation I decided there were a few things I wanted changed (partitioning, swap size, forgot to select/add "Laptop" at the package installation menu", etc).

I figured it would be easier to just go through the installation process again, this time with my desired configurations. I know, should have payed more attention the first time, but... oh well I guess.

Anyway, on the first run, the network auto-configuration utility automatically setup everything via DHCP. No problem.

However the second time, under the exact same circumstances... Network Auto-configuration failed. Typical "Your network is probably not using DHCP" message...

I plugged the cable back into another machine, just to make sure everything was operating smoothly... it was. Plugged it back into the laptop and tried again. Same thing.

I've been working at this, completely puzzled for the last hour. Any help or advice would be greatly appreciated... I know I can just configure it manually, but I'd prefer to let DHCP do it for me. Not only that, but now I just want to know why this is happening in the first place.

Thanks in advance!!

Is your home router providing DHCP ? If so...

There are enough DHCP problems with various routers to fill a book. Be sure to update your router's firmware to the latest version.

Yes, it is... as it worked perfectly the first time I installed...

Firmware is up to date :/ Just updated yesterday.

A client should release the DHCP lease when it shuts down the interface. The router should then take note that the IP is now available. When your client requests an IP again, it requests the same one. But this isn't possible in a LiveCD/BootCD situation, as there is no writable area to store and record the previous IP. So the system doesn't request a given IP, just a lease.

However, a DHCP server will also try to give back to the client the same IP previously leased. But it cannot do this if the client did not properly release the lease (the server still thinks it is owned). This is where a faulty implementation can go wrong.

Try restarting your router just before you do the second install. If it works, blame the faulty DHCP implementation.

I tried restarting the router earlier to no luck... even did a hard reset, hoping it might change something. Still no go. Hrmmmmm

To make sure I'm following what you're doing:

1) You boot from CD and install. DHCP works.
2) You shutdown
3) You boot from CD and install a second time. DHCP fails.

Restarting router at step 2 has no affect.

If this is correct, the only other things I can think of are:

a) multiple ethernet devices, enumerated differently across boots
b) buggy NIC driver
c) faulty hardware

If you have more than 1 ethernet device, try disabling the one you aren't using via BIOS and then do your test. If this isn't the solution, then assume (b) or (c). Let's hope its (a)...

Yes, those steps are correct.

It's unlikely to be A, because each time I try, the installer sees eth0 as a FireWire ethernet adapter, and eth1 as my actual RealTek NIC. I selected eth1 at the first, successful installation and every one since then.

I'm also not seeing anything relating to my NIC in the BIOS (Phoenix SecureCore).

Windows Vista Ultimate is already installed on the first primary partition of my drive, and it detects and uses my NIC just fine, thankfully (so hooray for it not being C).

Still stumped. Thanks for the help by the way, Mr. C. You're the only one who's put some effort into helping me find answers as of yet, I appreciate it, ha.

It might just be (b), esp. with a realtek NIC. So, if you can install once, maybe leave well enough alone until you can boot normally. Then, hopefully there will be some kernel or NIC driver updates that will resolve the problem (or potential problems).

Glad to (almost) help.

True...

I'm using a Realtek RTL8168/8111 PCI-E Gigabit Ethernet NIC, which debian loads driver r8169 for. I know that configuration has seen many problems, and I've tried solutions for each (enabling Wake-on-LAN at shutdown in my windows partition, powering off/disconnecting the cable for several seconds, etc) with no luck yet. Strange.

Also wouldn't help explain why it worked the first time, with the same drivers.. : (