Questions tagged [mac-address]

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), ...
Félix Saparelli's user avatar
101 votes
6 answers
122k 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 ...
Chris Magnuson's user avatar
35 votes
13 answers
52k views

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 ...
Erik Sjölund's user avatar
25 votes
4 answers
68k 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 ...
grapefruyt's user avatar
23 votes
4 answers
107k views

Duplicate MAC address on the same LAN possible?

Let's say someone is on the same network as me and spoofs their MAC address to match mine: Is this possible? Can two or more clients with the same MAC address be on the same network at the same time ...
Aaron's user avatar
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15 votes
3 answers
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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 ...
John R's user avatar
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15 votes
4 answers
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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 "...
The Shurrican's user avatar
12 votes
13 answers
39k 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 ...
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12 votes
1 answer
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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 ...
Luke's user avatar
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12 votes
2 answers
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Why do some mac-addresses repeat so often?

My application queries mac-addresses of client computers where it runs and stores them on the server. When I analysed the server DB, I found that some mac-addresses repeat 100-150 times. I.e. ...
Mike Siomkin's user avatar
11 votes
5 answers
175k views

Can I use nmap to discover IPs and mac addresses?

When I need to locate the IPs of devices by their mac address on a Windows system, I normally use Advanced IP Scanner (from radmin.com) to scan the network, then I use arp -a to list the mac addresses....
vfclists's user avatar
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10 votes
7 answers
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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 ...
Anthony A.'s user avatar
10 votes
3 answers
33k views

iptables, allow access from certain MAC addresses

Presently, I limit which clients can access my server by using IP addresses via iptables, only approved IP addresses can connect. However, the problem with this is if a client is on a laptop and goes ...
user788171's user avatar
9 votes
2 answers
24k 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). Also,...
Jon Bailey's user avatar
9 votes
2 answers
2k 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 ...
Tom O'Connor's user avatar
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8 votes
3 answers
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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 | +-----+ +------+ ^ +------+...
F. P.'s user avatar
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8 votes
1 answer
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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 ...
jurijcz's user avatar
  • 207
7 votes
5 answers
19k 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 ...
Joelbitar's user avatar
  • 195
7 votes
1 answer
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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 ...
Evan Carroll's user avatar
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7 votes
4 answers
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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 cloning the ...
Josh's user avatar
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7 votes
2 answers
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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 ...
Mutahir's user avatar
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7 votes
2 answers
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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 ...
Ruisu's user avatar
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7 votes
2 answers
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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 ...
Vineet Menon's user avatar
6 votes
2 answers
37k views

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 ...
username's user avatar
  • 4,785
6 votes
2 answers
50k 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 ...
jftuga's user avatar
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6 votes
1 answer
10k 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 176....
static's user avatar
  • 351
6 votes
2 answers
3k 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 ...
naugtur's user avatar
  • 284
6 votes
2 answers
2k views

iptables is occasionally logging MAC addresses. Why?

I have logging enabled on specific iptables packet drops. The rules I'm using are IP/port related only and this is what I can easily see in the logs, however occasionally I do get MAC address ...
rs232's user avatar
  • 105
6 votes
1 answer
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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 ...
Andy Coates's user avatar
6 votes
1 answer
2k views

Devices with MAC's manufacturer section "00:FF:01"?

While monitoring my office's network, I have seen a huge amount of traffic coming from devices whose MAC address manufacturer part (the three most significant octets) is 00:FF:01 I can't see the ...
Savir's user avatar
  • 169
5 votes
4 answers
2k views

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 ...
laktak's user avatar
  • 706
5 votes
3 answers
12k views

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 ...
St. John Johnson's user avatar
5 votes
4 answers
2k views

MAC address spoofing - why doesn't this work? [closed]

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 ...
loneboat's user avatar
  • 303
5 votes
1 answer
11k views

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 ...
jnm2's user avatar
  • 217
4 votes
6 answers
3k views

MAC Address Spoofing/Changing Software

What is the best MAC address changing/spoofing/editing program available for windows, mac and linux?
Daniel's user avatar
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4 votes
5 answers
4k views

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 00:30:48:fe:...
Aleksandr Levchuk's user avatar
4 votes
2 answers
5k views

Physical interface MAC rather than macvlan MAC is sent as ARP response [closed]

On Arch Linux ARM (Raspberry Pi) Kernel 4.4.37, I created a macvlan e.g. ip link add link eth0 mac0 type macvlan The macvlan virtual NIC then appears in the list so I assign it an IP address, and ...
bao7uo's user avatar
  • 1,714
4 votes
2 answers
4k views

ARP responds with single MAC address on Linux server with multiple interfaces on the same network

Linux server has 2 active network interfaces: IF:eth1 IP:192.168.1.1/24 MAC:11:11:11:11:11:11 (1GbE) IF:eth2 IP:192.168.1.2/24 MAC:22:22:22:22:22:22 (10GbE) The idea is that the ...
sardean's user avatar
  • 843
4 votes
2 answers
3k 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 ...
tacos_tacos_tacos's user avatar
4 votes
1 answer
2k 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 ...
Daniel B's user avatar
  • 113
4 votes
1 answer
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Debian: Where does a bridge interface store its MAC address and how can I change it?

I have reinstalled a computer and since I need several similar computers, I duplicated the hard disk with dd. On the target systems I have adjusted /etc/hosts, /etc/hostname and /etc/network/...
th0masrad's user avatar
4 votes
1 answer
3k 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 ...
mivk's user avatar
  • 4,442
4 votes
1 answer
2k views

How can I set the external interface for my bridge to be the same as my primary interface using networkd?

I've created a virtual bridge bridge0: bridge0.netdev: [NetDev] Name=bridge0 Kind=bridge bridge0.network: [Match] Name=bridge0 [Network] DHCP=yes and attached my primary interface eth0 to it ...
dippynark's user avatar
  • 242
4 votes
1 answer
3k views

Duplicate MAC address in VMware deploying from template

I am trying to deploy a VM from a template. This template has been used dozens of times before; nothing special. The problem is that seemingly out of nowhere when I deploy a VM, it's giving it the ...
briantist's user avatar
  • 2,555
4 votes
1 answer
3k views

Virtual interfaces with different MAC addresses

I try to figure out how to set up two logical network interfaces (at one physical interface) with separate MAC addresses on a Linux machine. My first attempt was to use macvlan which seemed to work ...
chwon's user avatar
  • 41
4 votes
2 answers
3k views

Why is networkd changing the MAC addresses of my bonded interfaces?

When I add the config files below into /etc/systemd/network and restart systemd-networkd, I find that the MAC addresses of bond0, eth0 and eth2 have all been changed to a single, locally administered ...
Isvara's user avatar
  • 215
4 votes
2 answers
2k 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 ...
user770395's user avatar
3 votes
2 answers
7k 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 ...
HopelessN00b's user avatar
3 votes
3 answers
3k views

Why need to send ARP to ask for MAC address when IP address is already unique? [closed]

In the usual networks, since every host has a unique IP address recognised among the stations in the network, why is a MAC address still necessary? Suppose a station A wants to send to Station B. ...
xenon's user avatar
  • 321
3 votes
3 answers
10k views

In Ubuntu, ensure that the same NIC gets assigned the same interface each time it comes up

I'm running an Ubuntu 9.10 server that has multiple NICs in it. I'd like to make sure that each time the kernel boots up, the NIC with MAC address 01:23:45:67:89:ab gets assigned to eth0 and the one ...
Lorin Hochstein's user avatar

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