MAC address

[VooDoo]

Hi,
Is it possible to have the MAC adress of the client that connect to a php
page?
I have the IP adress, if it's not possible to have directly is it possible
to query the DCHP server and have the MAC back? (it's for an intranet
purpose).
Any idea or help welcome!
Thanks,
VooDoo

[Gordon Burditt]

>Is it possible to have the MAC adress of the client that connect to a php

page?
If the client is on the same LAN that your web server is, maybe.
If the client is at an arbitrary place on the Internet, *NO*. In
this situation, the MAC address is likely never transmitted to the
web server. What you'll probably see if you can get hold if the
MAC address is the IP address of YOUR router.

And there's no guarantee that every machine even HAS a MAC address:
some guy with a 56K modem and no ethernet card won't have one, and
his terminal server at the ISP may have one - but it serves a
thousand dialup users. And your chances of even getting that are
slim to none.
I have the IP adress, if it's not possible to have directly is it possible
to query the DCHP server and have the MAC back? (it's for an intranet
purpose).

As far as I know, DHCP servers don't hand out that information.

If the client in question talks DIRECTLY to the server (hubs and
switches are OK, routers are not), then if it just asked for a web
page, the MAC address is almost certainly in the server's ARP cache.
I'm not sure how you get this info, but on UNIX systems grunging
through the output of "arp -a" or "arp -an" or perhaps "netstat
-nr", and picking the line with the relevant IP address or host
name might get you what you want.

You might also get this info out of the server or a managed switch
with SNMP. Of course, this means you need access to it (community
strings and SNMP has to be running on the machine you're asking).

Gordon L. Burditt

[VooDoo]

of course is not for internet user.
This is just on an intranet LAN.
Machine are on the same subnet.
And of course the DHCP Server has the mac adress, how will it give the IP
without it....
the question is, is this database "queryable"? Don't have a clue oon how i
could query the dhcp server to know the MAC of a specific lease....
If somebody know the anwer that would be fantastic!

The other option is the use the arp commands, but is this usable under php
command?

"Gordon Burditt" <go***********@burditt.org> a écrit dans le message de
news:ce********@library1.airnews.net...

Is it possible to have the MAC adress of the client that connect to a php
page?

If the client is on the same LAN that your web server is, maybe.
If the client is at an arbitrary place on the Internet, *NO*. In
this situation, the MAC address is likely never transmitted to the
web server. What you'll probably see if you can get hold if the
MAC address is the IP address of YOUR router.

And there's no guarantee that every machine even HAS a MAC address:
some guy with a 56K modem and no ethernet card won't have one, and
his terminal server at the ISP may have one - but it serves a
thousand dialup users. And your chances of even getting that are
slim to none.

I have the IP adress, if it's not possible to have directly is it possibleto query the DCHP server and have the MAC back? (it's for an intranet
purpose).

As far as I know, DHCP servers don't hand out that information.

If the client in question talks DIRECTLY to the server (hubs and
switches are OK, routers are not), then if it just asked for a web
page, the MAC address is almost certainly in the server's ARP cache.
I'm not sure how you get this info, but on UNIX systems grunging
through the output of "arp -a" or "arp -an" or perhaps "netstat
-nr", and picking the line with the relevant IP address or host
name might get you what you want.

You might also get this info out of the server or a managed switch
with SNMP. Of course, this means you need access to it (community
strings and SNMP has to be running on the machine you're asking).

Gordon L. Burditt

[Walker Pendleton]

On 5 Aug 2004, cr*******@ifrance.com wrote:

Hi, Is it possible to have the MAC adress of the client that connect
to a php page? I have the IP adress, if it's not possible to have
directly is it possible to query the DCHP server and have the MAC
back? (it's for an intranet purpose). Any idea or help welcome!
Thanks, VooDoo

Use arpwatch to make a table of your internal IP -> MAC pairings, and
then try looking up IPs on that table.

If you are familiar with the TCP/IP protocol stack, you'll understand
that you can only discover the MAC addresses of hosts on the same
local network, since the MAC address has to do with the lowest layer
-- the Link/Hardware layer of the stack -- and routers only forward
information from the Network (IP) layer of the stack & up. Therefore,
If your intranet is composed of multiple physical networks, you'll
need a machine running arpwatch on each physical network, and then
you'll need to collect all the data in a centralized location for
lookup.

[Gordon Burditt]

>of course is not for internet user.

This is just on an intranet LAN.
Machine are on the same subnet.
That doesn't always guarantee the path from the server to the client
doesn't go through a router.
And of course the DHCP Server has the mac adress, how will it give the IP
without it....
the question is, is this database "queryable"?
This is doubtful. There's no reason to implement such functionality.
A network driver needing the info will just use an ARP.
Don't have a clue oon how i
could query the dhcp server to know the MAC of a specific lease....
If somebody know the anwer that would be fantastic!

The other option is the use the arp commands, but is this usable under php
command?

If you can run an arbitrary command (in safe mode you can't), you
could use popen() to run "arp -a" and then parse through the output.

You might also get this info out of the server or a managed switch
with SNMP. Of course, this means you need access to it (community
strings and SNMP has to be running on the machine you're asking).

PHP does have functions to query SNMP if it is compiled with those
options.

Gordon L. Burditt

[Colin McKinnon]

Gordon Burditt wrote:

of course is not for internet user.
This is just on an intranet LAN.
Machine are on the same subnet.

That doesn't always guarantee the path from the server to the client
doesn't go through a router.

but...what is it you are trying to acheive? Access control by host is a
waste of time, particularly as PHP implements sessions so well using
cookies. Also mac addresses can be spoofed a lot more easily than IP
addresses.

C.