Puppy Linux Discussion Forum

BarryK · Posted: Wed 30 Jul 2008, 22:27 Post subject:

Correct me if I'm wrong, but isn't the MAC address simply the hardware address of the network interface device.

In my case, I'm using the same wireless hardware, so of course the address will be the same whereever I take my laptop.

A side note, I'm using a D-Link DWA-110 USB wireless unit with my laptop, as I could never get the internal wireless hardware to work.

Therefore, the problem as I asked in my previous question, still remains. The MAC address is a constant whereever I take my laptop, but I need to connect to different wireless networks.

Actually, do you need to use the MAC address at all in the profile name -- why not a random number? or the date? The MAC address, can be inside the profile file.

The thing is, I need to create a profile for each of the places I go to, so the profile file must have a different name for each. I imagine a lot of people would have the same situation as me.

Dougal · Posted: Thu 31 Jul 2008, 04:18 Post subject:

BarryK · Posted: Thu 31 Jul 2008, 06:59 Post subject:

Dougal,
No, the MAC address is the hardware address of the actual network card/hardware on your PC, not the external thing that you connect to.

That's what I always understood, so I was puzzled about the choice of MAC address for the profile files in the new Wizard.

I can prove it right now. If I run ifconfig, and look at the wlan1 information, it shows eactly the same MAC address as when I was at my relative's place:

wlan1 Link encap:Ethernet HWaddr 00:1C:F0:0A:53:F8

They refer to it as the HW (hardware) address, which is a far less confusing name than "MAC".

Perhaps name the profile as a combination:
<mac address>_<date>.profile.
...although, it would be nice to have a more meaningful name...
er, why not just ask the user for a simple name to uniquely identify the connection, like, in my case:
perenjori_internet.profile
relative_1_internet.profile

nic2109

Barry's correct.

Every Ethernet device has its own unique "hard wired" MAC address. The Router associates the MAC address to the I/P address either via DHCP or manual assigments. The Router will of course have its own MAC address but that's irrelevant.

jcoder24 · Joined: 06 May 2005 Posts: 601 Location: Barbados

Barry is right about the mac address. However, it should be possible to use the mac address of the gateway that you are connected to.

When the wireless connection is complete it most likely would have a default gateway for the assigned interface. You would need to determine the ip of the gateway and then use that to get the mac address for it. To determine the mac you need the arp binary, which is small ~40k, and would be nice to have in the default puppy Wink

.

You can use something like this:

Dougal · Posted: Thu 31 Jul 2008, 14:45 Post subject:

BarryK · Posted: Thu 31 Jul 2008, 22:46 Post subject:

Dougal,
No, the MAC address that you are using for the profile names is that of the network card, not the access point.

I just checked. I reran the Wizard. Here at home I have a different router, my "profile name" is "belkin45g", in Perth it was "WLAN", these are how the networks have identified themselves when scanned.

Anyway, the point is, the .conf files are named with the MAC address of the card, not the access point.

Question for the experts: isn't it possible that the MAC address of the access point could change, in cases where you are connecting via some kind of wireless network provided by the ISP? They might have a sophisticated router system where you might connect to a different MAC address each time. Just a thought.

Oh yes, your comment that the MAC address will be that of the access point if your computer is setup as the router is correct, but that is not how most people connect. I have an external router/modem and in my case the MAC address that you are using for the .conf file names is not that of the router/modem, it is that of the USB D-Link wireless thingy that is plugged into my laptop.

PaulBx1 · Joined: 16 Jun 2006 Posts: 2308 Location: Wyoming, USA

Starts to sound like the files ought to be identified by the ESSID, not the MAC address.

ESSID is after all an identifier. It should be usable as such. It is not our problem if a certain user has an ESSID of "linksys" both at work and at home; it's up to him to configure his router to have a usable, unique (for him) identifier (and very few company admins are going to leave a default ESSID on a router anyway).

Of course, there is still the support issue here. We will run into users who do have the same ESSID on two different APs and who won't know why one of their internet connections don't work. How is the network wizard to tell him to set him straight? Should we just have some text that says so? Should we have a text box warning if two profiles are created with the same ESSID?

On reflection, I can see the appeal of the MAC address; it requires nothing like the configuration of a router, which is beyond some users. But there has to be a way to get the address of the AP. What's the deal here, is this simply not available, or does it need a working connection to be established first (chicken or egg problem)? I guess the network scan does not provide it?

There is also a possible fallback for the sort of people who use default values in their routers. These people could switch networks the same way I do it in 2.16: going into the network wizard and simply telling it which profile to use.

Which makes me wonder. Why after all do the different files need to be named with MAC address or ESSID? Why not just let the user supply the name, just like in earlier versions of the network wizard, and the boot code simply compares the values found in the scan with every file's contents in that directory? It can't take that long to scan through a few short text files. That way, a naive user really could have a profile that worked for two different APs. Buy two linksys routers, plug 'em in, and bang, they both work, without configuration. Why is this a bad thing? Outside of being dumb, because not using encryption?

jcoder24 · Joined: 06 May 2005 Posts: 601 Location: Barbados

dogone · Joined: 21 Apr 2008 Posts: 202 Location: Arizona, USA

Time to throw in my 2 (your currency)'s worth.

As to "what is a MAC address", Wiikipedia has an excellent, if somewhat technical explanation: http://en.wikipedia.org/wiki/MAC_address.

The current convention is to identify wireless networks by ESSID only. This generally works well but depends upon the owner/operator assigning a unique (to his area only) ESSID and broadcasting the ESSID (the default, but optional). Any number of networks can employ the same ESSID however, at the same location or at many. Bottom line - the ESSID does not positively identify a network.

Unlike the ESSID, a MAC address is unique in the world. It identifies one and only one piece of network equipment. Replace your AP and systems configured to seek out that MAC address will fail to find your network.

Employing MAC addresses to identify a network is also problematic where several pieces of hardware serve one wireless network. Say you are at the north end of you airport and find an airport wireless AP. You save the profile "airport" based on the AP's MAC address. You now walk to the south end of this big airport and attempt to re-establish the connection. You laptop fails to find the "airport" connection simply because the AP identified by that MAC is out of range. The several closer airport APs are ignored.

Many wireless scanning utilities, including Pwireless, address this problem by displaying both the ESSID and the MAC address. The careful user can then correctly identify any wireless network, no matter the network's ESSID or the equipment it employs (MAC).

The best solution in Puppy's case may be to track networks by both ESSID and MAC and to, for security purposes, inform the user when these no longer match those on file. Thus, if Barry swaps out his faulty AP or changes it's ESSID, we still stand some chance of finding his network. We also stand a good chance of detecting a pirate AP (Ubuntu spies) using Barry's ESSID.

Dougal · Posted: Fri 01 Aug 2008, 10:56 Post subject:

erikson · Joined: 27 Feb 2008 Posts: 735 Location: Ghent, Belgium

Re MAC addresses:

To the best of my understanding, ifconfig returns the MAC address of your PC's interface, while iwlist returns the MAC address(es) of the wireless access point(s). For my network at home:

BarryK · Posted: Sat 02 Aug 2008, 06:36 Post subject:

The idea of using a unique custom name that you yourself create, seems nice, but I am reminded of a situation awhile back. I was helping someone on a Windows XP system to get their external USB wireless unit working, and if I recall rightly it came up with a window asking the user to type in a name for the profile -- and that is one place where he was confused -- what should he type in there? That's what he asked me. It could be any name he desired, but that was not explained by the Windows setup program.

The wireless setup program in that case, came on a CD and was not the built-in Windows wireless setup.

So, if we can eliminate that step, that's one less thing to cause any possible confusion. Unless the custom name is explained very clearly.

Aitch · Joined: 04 Apr 2007 Posts: 6825 Location: Chatham, Kent, UK

FWIW - I'm with erikson

that's what I use

in windoze from run/cmd

ipconfig /all

is the same as ifconfig in linux

useful iwlist info may help clear up confusion [can use in win & lin]

http://www.newlinuxuser.com/howto-use-iwlist/

Aitch
Edit:
I trust you've seen urban's autoconnect, dougal et al?

http://www.murga-linux.com/puppy/viewtopic.php?p=179387&sid=13dd751ee9c77f1b130fcfe457c352b9