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Author Topic: Mac Address's  (Read 1674 times)

tickmike

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Mac Address's
« on: July 12, 2013, 12:44:33 AM »

Does a 'Network switch' have a Mac address ? if so how do I read it on my Home Lan  :hmm:.

With     # arpscan -p wlan0 192.168.0.1/24       in a Linux Terminal I can see The Mac address's for my Laptop, My two Access Points and my Hardware firewall (Smoothwall).

Also using 'Nmap' program it see's the same !.
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sheddyian

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Re: Mac Address's
« Reply #1 on: July 12, 2013, 11:02:57 AM »

I don't think it does, because it doesn't need to.

I've set up a fair few (unmanaged) switches, can't say I've ever noticed one with a sticker saying what it's mac address is, or any interface to allow you to change anything.

(Obviously routers and managed switches are a bit different - I suspect (but don't know) they might well have their own mac address because I'd assume they need their own ip address).

This site has a nice animation of a switch in action (click the options on the left of the picture to watch).  Looking at that, I can't see why it would need to have a mac address. 

http://www.howstuffworks.com/lan-switch11.htm

Happy to be proved wrong by someone with more knowledge of networking though :)

Ian
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tickmike

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Re: Mac Address's
« Reply #2 on: July 12, 2013, 04:39:29 PM »

Thanks, I did think they did not need them but I wanted to be sure before I do some in depth investigation into why my daughters laptop does not want to connect on to the internet even though it's got a IP address via one of our two AP (access points), (it's ok with an RJ45 LAN cable connection  :'( ).
One post I noted with a chap had similar problems on a school network it was somehow getting it's IP address via one AP and it's MAC address off another AP  :o  .
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I RECOMMEND TRYING PCLinuxOS (www.pclinuxos.com).
I have a set of 6 fixed IP's From my Kcom Business isp.
BT ADSL2 (G992.3) line>HG612 as a Modem, Bridge, WAN Not Bound to LAN1 or 2 >pfSense (Hardware Firewall and routing) > Ethernet LAN, DMZ,WiFI LAN and Spare LAN .
DSLstats LAN2 linked Ethernet

sheddyian

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Re: Mac Address's
« Reply #3 on: July 12, 2013, 04:50:55 PM »


Mac addresses are fixed and unique to each network interface - they're not assigned in the way that an ip address usually is.

If you've got 2 wireless access points, I wonder if one of them is giving out incomplete/wrong information , ie the default gateway address?

If it's a Windows computer, the command ipconfig will tell you what it thinks the default gateway address is, as well as other information about your interface and address. 

(Sorry, I'm not familiar with Mac or Linux so don't know the equivalent commands for those).

I did have a similar sort of problem myself a while back, I'm using an old router/modem as a 2nd wireless access point, and found that although the DHCP from the ACTUAL router/modem was correctly being passed through, the address of the default gateway etc wasn't.  The result was that the computer requesting an address would be granted a valid address, but had no default gateway set, and so failed to access the internet, yet could ping and be pinged.

Ian
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