A Media Access Control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment.

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Why couldn't MAC addresses be used instead of IPv4|6 for networking? [closed]

I am reading up on TCP/IP and other related protocols and technologies. MAC addresses are described as being (reasonably :) unique, and as having a large possibility space (several hundred trillions), ...
27
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5answers
23k views

What range of MAC addresses can I safely use for my virtual machines?

I want to assign my virtual machines MAC addresses so that I can configure DHCP reservations for them so that they always get the same IP address regardless of which host hypervisor they are running ...
14
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3answers
1k views

Look up manufacturer based on Mac Address?

I want to incorporate into a piece of software the ability to look up a manufacturer based on a mac address. By googling "mac address lookup" and similar, I have noticed several websites that make ...
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1answer
4k views

VirtualBox cloned Ubuntu Server network error

I run a number of virtual servers on my network and I want to be able to easily clone base installations of Ubuntu Server. I use the VBoxManage command to clone the actual hard disk and I then create ...
11
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13answers
20k views

How to discover the MAC address of machines in a network?

How do I discover the MAC address of machines in a network? I need to discover the machines that are available just with only BIOS installed (no operating system). And I need to find the MAC address ...
10
votes
7answers
754 views

What's a good way to handle multiple devices with the same MAC address on one network?

The devices I'm working with come off the production line all set to the same MAC address. I can set each one to have their own static IP, and I'm wondering if there would be a way to connect them to ...
10
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4answers
3k views

Is a Network Switch IP-Aware?

I have some very trivial basic questions about networking, but I find varying information on that, so I just wanted to settle this. As far as I understand a Network Switch handles traffic ...
10
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4answers
15k views

multiple MAC addresses on one physical network interface (linux)

Simple question: How can I setup multiple MAC addresses on one physical network interface (linux)? Why? My ISP is checking ip<->mac on GW and I d like to route traffic through my "linuxbox" and ...
9
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2answers
638 views

MAC addresses on dual-NIC mainboards

Here's a weird problem. We've got a number of devices with dual-NIC mainboards. Some are Realtek NICs, which suck. Some are Intel e1000s, which don't. I've just noticed on 2 machines, one is an ...
8
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5answers
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how to generate a random MAC address from the Linux command line

How do I generate a random MAC address from the Linux command line? I search for a solution that only requires standard tools commonly found on the Linux command line. The MAC address will be used ...
7
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2answers
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NIC Teaming with Broadcom on HyperV 2008 R2

I have a HyperV cluster made up of 3 hosts. Each host is connected to both of my Nexus 5548 switches running in an etherchannel. LACP on the switch and NIC teaming using Broadcom 802.3ad on the server ...
6
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2answers
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A nice tool to look up make/model via MAC address?

The first several digits of a MAC address (Ethernet ID) are specific to its manufacturer/model. I won't ask what's the best way to look these up since it's subjective... but I'd love to know if any ...
6
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1answer
3k views

Is bonding mode=5 a solution against MAC flapping?

There is two are interconnected Cisco WS-2950T. By the one GBIC port on first switch connected a first NIC of bonding interface, and by the one GBIC port on second switch connected a second NIC of ...
5
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4answers
682 views

MAC address spoofing - why doesn't this work?

So I'm in a new job, and they're pretty draconian about their network, hardware, and OS security. :-( I'm a web developer, but am forced to use IE7 for development simply because they don't want ...
5
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2answers
2k views

Can I get the original MAC address after it has been changed?

I am using some linux machines that have had their MAC address changed. I would like to be able to read it back with a shell script. Is the original MAC address stored anywhere except the sticker on ...
5
votes
2answers
3k views

VirtualBox Import & Same Mac Address

Exported Virtual Box VM (CentOS 5.5 with Guest Additions Installed) - Success Imported CentOS VM Successfully on another Windows Machine via Windows Batch Problem : VM After Import retains the same ...
5
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2answers
1k views

Can I create a pf rule involving MAC address instead of IP?

The title is self explanatory. I want to create rules in pf running on OpenBSD 4.9 for perticular MAC address, something like pass in on eth0 from mac 00:04:34:5f:34:33 to mac 34:32:34:06:5e:22 I ...
4
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3answers
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Ethernet frames: what are the source and destination MAC addresses?

Imagine you have some network configured like this +-----+ +------+ +------+ +-----+ |comp.|---|bridge|---|router|---|comp.| | A |---| B |---| C |---| D | +-----+ +------+ ^ ...
4
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6answers
2k views

MAC Address Spoofing/Changing Software

What is the best MAC address changing/spoofing/editing program available for windows, mac and linux?
4
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5answers
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DHCPDISCOVER requests from an off-by-one MAC address

In a Linux DHCP server I'm getting a bunch of these log lines: dhcpd: DHCPDISCOVER from 00:30:48:fe:5c:9c via eth1: network 192.168.2.0/24: no free leases I don't have any machines with ...
4
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5answers
3k views

How do I MAC filter with DHCP server

I want to Only allow certain MAC addresses to get a IP from my DHCP server, currently I use dnsmasq and I rather not change dhcp server but I'm open to other software aswell. However, I need to be ...
4
votes
1answer
389 views

Two NIC card with same mac address

Yes its very strange but I have got two server having same H/W MAC address. The issue which I am facing is again very strange. 1st Server is normal windows server. 2nd Server is running KVM on ...
4
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3answers
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What does ifconfig promisc mode do, or promiscuous mode in general?

This is what man ifconfig has to say about it. [-]promisc Enable or disable the promiscuous mode of the interface. If selected, all packets on the network will be received by the ...
4
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1answer
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How can I change the MAC address of a network bridge in Windows?

I use DHCP reservation rather than static IP for convenience, and that relies on the MAC address of my computer. I recently bridged my main adapter with my VirtualBox adapter. When things stopped ...
4
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4answers
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Will MAC filtering increase Wifi security?

I've always thought that you should enable MAC filtering to increase Wifi security (in addition to using WPA2). Now I've found this article (Wireless LAN security hall of shame) that says MAC ...
4
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3answers
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How does VMWare generate unique MAC addresses?

I'm looking to build a series of VMWare Virtual Machines as my client needs them. The hostnames and IPs have been pre-assigned. But I'm going to need to add rules to our switches for each host's MAC ...
4
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1answer
819 views

Assign DHCP IPs for specific MAC prefixes on Windows Server 2008 R2

I'm running Windows Server 2008 R2 for my DHCP server. We are about to switch over to a VoIP system and Cisco VoIP phones. I would like to assign a specific range of IPs to these phones which will ...
4
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2answers
9k views

list known mac-addresses on Dell PowerConnect 5324

I have a Dell PowerConnect 5324 (SW version: 2.0.1.3) which I hardly ever use. I need to list out the mac-addresses it sees on certain ports, such as g23. I have fooled around with the cli and done ...
3
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2answers
5k views

Assign DHCP IPs for specific MAC prefixes

I'm running a ISC DHCPd server for my network serving a number of subnets. One of the things I would like to do is assign a specific range of IPs to hosts with a common MAC prefix (ex. 00:01:02). ...
3
votes
2answers
1k views

What is the Cisco iOS (CLI) command to display a WAP's Radio MAC address?

I can't believe I'm unable to find this with teh g00glez or by RTFMing, but does anyone know how to display the MAC address of a Cisco WAP's Radio (wifi connection) from the command line? show ...
3
votes
2answers
943 views

Deny Static IP Assignments

I am currently using a SonicWall Pro 2040 with DHCP enabled, but only with static IPs mapped to specific MAC addresses. There is no dynamic IP scope being used. Currently, no DHCP request will resolve ...
3
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2answers
1k views

Using DHCP with Multi-Homed NICs

I am trying to steer away from our current manual addressing system and embrace the decades-old wonder of DHCP. In our domain and even at my home network DHCP is great - I can use address reservations ...
3
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4answers
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What happens if two computers have the same MAC?

Possible Duplicate: Can duplicate MAC addresses on same LAN cause trouble? What happens to network traffic on a switched LAN if two devices have the same MAC (probably because one is ...
3
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2answers
103 views

What does the MAC setting on an interface do to the ability to transmit frames?

I'm told that an interface can transmit a frame no matter what the OS has set for the interface's MAC. I'm also under the impression this is how VMs do host-bridging. If that is so, then what uses the ...
3
votes
1answer
146 views

Gather mac addresses of domain computers, preferably from command line

In preparing to move to a domain and SCCM to manage machines in a new office I need to gather their MAC addresses. I could go from machine to machine, run ipconfig and gather the ip, but that would ...
3
votes
1answer
3k views

Ubuntu Linux - two interfaces, same subnet, different vlan - MAC/ARP issues

I'm attempting to setup a server that needs to have interfaces on the same IP subnet, but different VLANs: eth1.102 Link encap:Ethernet HWaddr 00:50:56:b1:00:0f inet addr:10.1.1.6 ...
3
votes
1answer
1k views

cloning mac address of physical server converted into vmware server

We've recently converted a physical Windows Server 2003 into vmware using P2V. However, one of the pieces of software on the 2003 machine are still looking for the old server's network MAC address in ...
3
votes
2answers
1k views

How do I find out which physical port my ethersvi MAC address corresponds to on a Cisco switch?

I'm doing a layer2 network map (my first) and this is the first virtual mac I've encountered. From the mac address table of switch1, I have VLAN 1 6416.8d98.52c0 DYNAMIC Te0/1 and on the ...
3
votes
1answer
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Windows 7 Machines do not take reserved IP address from DHCP

I have NETGEAR router - WGR614 V6 and have mixed network of Linux machines and windows PCs. I use the router's in-built DHCP. I use 'Address Reservation' feature of the router to reserve IPs based on ...
3
votes
1answer
380 views

nmap and arp-scan inconsistent IP-MAC results

I seem to get variable and inconsistent results for the IP/MAC addresses from a particular machine, using nmap or arp-scan. The machine has 3 interfaces, and this is what it shows: $ uname -a Linux ...
3
votes
1answer
385 views

Windows Server 2008 ARP Cache Poisioning

Recently ran into a very strange problem. Several applications were having issues communication through our F5 Load-Balancer. When we looked into it we found that the router had an incorrect ARP and ...
3
votes
2answers
844 views

Manually set IPv6 neighbor's MAC address in Mikrotik's RouterOS

I have an interesting problem. An ISP of ours started providing native IPv6 on their network. They provided us with a /56 prefix and a /126 linking segment (::1 being their endpoint and ::2 being ...
2
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5answers
3k views

Find the network card mac address in Windows

How can I find the network card mac address in Windows (7)?
2
votes
3answers
631 views

How to prevent MAC spoofing?

I want to define in my Cisco switch a whitelist of allowed MAC, but MAC spoofing could allow any host to connect. How can I prevent MAC spoofing?
2
votes
3answers
285 views

Can I run a single DHCP Server for all branches of an MPLS?

We have a two-location MPLS. I am told by the ISP that I can have a single DHCP server to service both branches. But I don't understand this. Consider this: Location1 (Host branch with the DHCP ...
2
votes
1answer
362 views

Cisco switch:change mac type from dynamic to static in console

How to change mac from static to dynamic in mac-address-table (switch)?I find this official source but still not understand what options I must choose. Something like this: switch(config)# ...
2
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3answers
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What security problems are caused by public MAC address knowledge?

What types of attacks are made possible or worse by having knowledge of a target computer's MAC address? I am planning on using a type 1 UUID generator that includes the generating computer's MAC ...
2
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1answer
842 views

Why are eth0 and vmbr0 (bridge) having the same MAC addresses?

I configured my Debian (with KVM on board) as following: /etc/network/interfaces: auto lo iface lo inet loopback auto eth0 iface eth0 inet manual auto vmbr0 iface vmbr0 inet static address ...
2
votes
4answers
387 views

Newbie questions on MAC and high availability failovers

I am reading about High Availability and I can not understand the following I read: On failover the primary IP migrates to the backup server BUT so must the MAC address. Specifically I read that ...
2
votes
3answers
566 views

On CentOS 4.5, How to Masquerade a connection using MAC address?

Currently we give Internet access using ip address in our firewall script as follows iptables -t nat -A POSTROUNTING -s 192.168.1.40 -j MASQUERADE But we have noticed that some guys steal these ...