How to get MAC address?

ping it and then do an arp -a

Whenever I ping different IP address I have same MAC address (it is not changed)  :-(

Interface: 149.99.21.72 on Interface 0x2
  Internet Address      Physical Address      Type
  24.28.36.133          20-53-52-43-00-00     dynamic  
  24.66.81.234          20-53-52-43-00-00     dynamic  
  24.141.93.163         20-53-52-43-00-00     dynamic  
  62.195.62.61          20-53-52-43-00-00     dynamic  
  68.84.70.171          20-53-52-43-00-00     dynamic  
  68.117.97.136         20-53-52-43-00-00     dynamic  
  80.222.2.42           20-53-52-43-00-00     dynamic  
  80.222.8.54           20-53-52-43-00-00     dynamic  
  131.220.99.52         20-53-52-43-00-00     dynamic  
  149.159.11.232        20-53-52-43-00-00     dynamic  
  168.28.247.130        20-53-52-43-00-00     dynamic  
  200.82.40.10          20-53-52-43-00-00     dynamic  
  204.50.251.17         20-53-52-43-00-00     dynamic  
  205.138.3.102         20-53-52-43-00-00     dynamic  
  206.169.61.185        20-53-52-43-00-00     dynamic  
  207.107.254.9         20-53-52-43-00-00     dynamic  
  216.65.31.4           20-53-52-43-00-00     dynamic  
  216.73.86.210         20-53-52-43-00-00     dynamic  

You're pinging stations on a remote network.

ARP is correctly reporting the MAC address of your router...

If you ping a machine on your own IP network, you'll be able to see its MAC address.  Anything not on your own IP network, ARP will return the MAC address of the router to which it passed the packet.

So are there any way to get MAC address of computer on remote network?

if the other end has snmp, its then possible i think

You need to have something running on the remote end.  

Any sort of software that can query the hardware of the remote machine should be able to retrieve the remote station's MAC address.  WMI, for example, can do it.

If you can remotely monitor segments on the remote networks, you could get the MAC addresses, too.

If this is on a LAN you could check at the DHCP server but I presume from your list they are real internet addresses?  Likewise you can ping and arp -a from a server or equivalent from a router console on the same subnet.

Why do you need to know the mac address remotely though - surely it is no use outside the subnet anyway except as perhaps a "unique" number?

Steve

You cannot directly find out MAC addresses if the device is on a remote subnet. SNMP is probably your best bet if it is running on the remote device - otherwise you could put a sniffer on the remote lan and look at the packets before they hit the local router at the other end.
If you do not have control over the remote lan then you are out of luck.

On the same note as dragon-it mentioned - why?

There are several hacker utilities that will grab this info, but outside of attempting some type of hack, there should be no need for this info.

We need to restrict access to database to authorized computers only and this could be additional method when use MAC address as unique identifier

Well a MAC address from a remote computer is never seen as you have experienced by looking at your arp cache.  There is no option to do it by IP address?

IP address often being changed in case of laptop... When it is connected to the Internet in different town...

Yes, but there is no way to tell what the MAC is.  In reality, any security you use that involves allowing IP addresses etc in a true user environment is total crap.  That of course doesn't help you much.  If I were in your situation, I would create a VPN scenario, and allow users that come in through the VPN via an internal IP or MAC.  This way, you at least have some authentication first.

Oh yes and you can change the mac address of many cards to be what you want so it is no real security check.

very true, dragon-it

Ok, looks like impossible.
But what are these "hacker utilities that will grab this info" ?

Well there are many free port scanners out there, so I'll let you do your own searching on those.  But to give you an idea, here is a security port scanner that will give you this info (provided there aren't firewalls in the way):

http://www.gfisoftware.com/lannetscan/index.htm