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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How can I assign human-readable names to MAC/ethernet addresses without knowing the IP address?

I am using tools like airodump-ng and the output lists BSSIDs as MAC addresses. However, some of these stations (and clients) are known to me and I would like to tag them, or name them, something. I ...
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Do computers have IP address? [closed]

Everywhere I search some people say 'a computer has a permanent IP address' and some people say 'it doesn't but has only when it is connected to the internet through a router'. So my understanding is ...
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can ping but not arping via OpenVPN

I'm working on a remote machine using OpenVPN at a customer's network. The IP addresses there change dynamically and (until they get hostnames to work properly which is not in my hands at this point) ...
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Cloning machines and mac addresses / uuids

Recently I came across a task to setup 11 laptops for my work. Done it before many times with interactive white boards (Tv monitors which include OPS - mini pc).That boards were given to different ...
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Mac address flapping during VM migration in WSFC

I am trying to troubleshoot an issue with our servers on a customer network. We do not support the network infrastructure. For example, I have 2 nodes(WS2019) in the Failover Cluster. Each NODE have 2 ...
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198 views

What are the symptoms of an IP address conflict?

System administrators must take special precautions when setting up two DHCP servers on the same network. The most common problem caused by competing DHCP servers is an IP address conflict. Windows is ...
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How to give permissions to local computers using computers' MAC addresses in Windows Server 2016 for file sharing

I have the following issue: I have a server with Windows Server 2016, and I need to use it only for saving, reading, and modifying files with file sharing. The way I have the restrictions is with ...
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Same VIP different MAC

I am observing this behavior on a dual-homed server that is sending traffic in active/active mode on its 2 links connected to the same uplink switch. The server is running IPMP so it generates traffic ...
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Centos 7.6 MAC addresses change for a network interfaces

On one of the CentOS Linux release 7.6.1810 (Core) server the mac address's of networfaces got changed e.g. eth0 has eth3's mac address and so on . Does anyone know why this happens and how to resolve ...
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LAN static lease for Hyper-V VMs

I have a question about reserving IP addresses for VMs that run on my laptop. In this case, my laptop serves as a switch. But the thing is, how can I lease a VM an IP address in my LAN by MAC, as all ...
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if all of the world used IPV6, there is no need to have mac address anymore?

Mac address can not replace IP address, because Mac address is immutable, and there is no Prefix concept in Mac address. So why IpV6 can not replace Mac address? Do we still need Mac address when all ...
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902 views

Is it possible to check the MAC address of TCP-connected host (on same LAN)?

I have an Ethernet LAN (192.168.1.0/24) with a number of hosts, which are all assigned addresses over DHCP by a router. Due to the way that DHCP is set up the IP addresses of particular devices can ...
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928 views

Azure Network Interface physical MAC address

I am trying to run some third-party software on an Azure Linux VM but their licensing is tied to the MAC address. The private and public IPv4 IP addresses of the Network Interface for the VM are both ...
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Why is the mac address that appears on my computer the same?

I use the 2 ethernet interface on the my system board, eth0 / eth1(usb to ethernet) like the followings. root@E3-RDP:~# ifconfig eth0 Link encap:Ethernet HWaddr ae:a1:99:48:86:79 inet addr:10.10.0....
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How to run several ESXi VMs that must have the same MAC address?

For various reasons I have to run a few (≈6) clones of the same virtual machine at my lab ESXi server at work and unfortunately the MAC address must not be changed between the clones. Changing IP is ...
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Get information about MAC address

My router (FritzBox 7330) shows tons of errors about a device that continuously try to connect to my network: 23.12.19 10:17:07 Registrazione del dispositivo wireless fallita: chiave wireless ...
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Use IPv6 from MAC for DNS?

I am running a private cloud server and I am facing the problem that my DNS provider does not support dynamic update of the IPv6 address. I know that every IPv6 device has a 'default' IPv6 address ...
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1answer
290 views

Why do some unknown hosts show up with nmap option-sL , and not with -sn [and do I need to worry about them]?

Initial Disclosure I am not a network engineer and my expertise in this area is low. Background while using nmap 7.70 with nmap -sL to look for the IP address of a known device on our local ...
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407 views

How to use my router's Mac Address on Pfsense installed on Esxi

My ISP bind my router's Mac address so only this router can connect to their pppoe server, now I want to connect it on Pfsense installed on Esxi for better configuration options but pppoe server is ...
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1answer
529 views

Different MAC addresses in packet and ARP table

What happens if a host on the network receives an IP packet with a MAC source address that differs from the MAC address in the local ARP table for that source IP? The ARP table entry for that IP was ...
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1answer
105 views

IPv6 NAT information leakage [closed]

Edit: Since I was asked to edit this, I'll ask about an awfully specific issue. The question was obviously never about information leakage on OSI layer 7, since that wouldn't be a network issue. I'm ...
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651 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 ...
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111 views

Can I use source MAC of Ethernet packet for UDP reply instead of ARP lookup?

I'm working on an embedded platform with very limited resources where I need to build my own Ethernet frames. If I need to answer a UDP request with a UDP reply, is it ever not OK to just send the ...
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3k views

Getting a static MAC address on AWS EC2

I want to ensure that my AWS EC2 instance has a static MAC address (for an app that ties the license to the MAC address). From what I read I just need to add an ENI to the instance to get a static ...
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How to solve Event IDs 16945 in the System logs Hyper-V MAC conflicts

After 3 years of running perfectly with Hyper-V I am all of a sudden having network problems with Hyper-V on win 2012 R2. I set up my servers 3 years ago and never had these problem until this week. ...
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712 views

Get mac address based on ip in filter wireshark

i am a test engineer writing some test cases. I am trying to write a test which has to be performed in wireshark. However, my collegues aren't that "into wireshark" and i would like to keep it as ...
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968 views

ARP table not updated until response is sent

I'm executing the arp -a command on CentOS 7 in order to translate an IP address to a MAC address (since I can't access the source MAC of the layer 2 frame in Java). I see a lot of cases where the ...
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1answer
240 views

Monitor for duplicate MAC addresses?

We just had our third incident of a duplicate MAC address from provided hardware in 2 years. I know it's possible to override the MAC in software, but detecting it during troubleshooting can take ...
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1answer
1k views

Possibility of detecting MAC address spoofing in a decentralized network? [closed]

The paper that has been published here: https://dl.acm.org/citation.cfm?id=3282283 proposes a consensus algorithm based on distributed voting process in which it claims that it would be possible to ...
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What happens if a USB Ethernet Adapter has the same MAC address as the PC's network card it is connected to?

What happens if a USB Ethernet Adapter has the same MAC address as the NIC? Is it possible for internet connection to pass through the usb-ethernet adapter succesfully or not, in that scenario?
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1answer
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hostapd: mapping MAC address to VLAN ID (static mapping via accept_mac_file)

I want hostapd to assign each station a given VLAN based on MAC address. BTW, my network is quite small. Using RADIUS would be an overkill. According to the hostapd manual: Optionally, the local ...
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On VirtualBox, is there a way to set 'Reinitialize MAC address' as default?

When cloning a VirtualBox instance, is there a way to set the "Reinitialize the MAC address of all network cards" as the default? Humans sometimes forget to tick this box, with the resulting horror ...
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How to setup my MAC address to be static using OpenVPN on Ubuntu 16.04?

I'm connecting to a server using vpn connection. So, every time that I connect using this VPN, my PC (Ubuntu 16.04) always create a virtual netboard and gives to me a new MAC address. But for what I ...
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4k views

ISC DHCP assign pool/subnet to certain MAC addresses

Hej, desperate here! I'm running isc-dhcp-server 4.1 here (with webmin but that's another topic) and want to give some options (tftp-server and bootfile) to network-components that I can identify by ...
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1answer
7k views

How to reserve a static-ip on Mikrotik router for a device that is attached to a fixed router's Ethernet port

I am trying hard to figure out how can I force any DHCP client device connects to the port ETH10 on Mikrotik router get assigned a fixed IP-address. Please note that the device MAC address is unknown ...
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1answer
3k views

ESXi VMs randomly lose network on reboot; only resolution to pull NICs and reassign new NIC driver with static MAC

We have one ESXi server (HP-ESXi-6.0.0 build-2492585) that has multiple VMs on it that have exhibited the following behavior: When the VM is rebooted it will occasionally just lose all network ...
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4answers
769 views

Why does two different interfaces on the same machine result in two different MAC addresses?

My machine named debian has two different MAC Addresses. One for Wireless and one for LAN. I thought a device only had a single MAC address. How is this possible?
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Port forwarding by MAC address problems

I have a server sitting behind a Huawei HG569 router. Port forwarding has been set up through the router and, when it works, it works as one would expect. Now, the problem is that the HG569 router ...
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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 ...
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How to find a server connected on network?

earlier this week we physically installed a machine in our server rack and connected it to our network switch. It has Scientific linux installed but we don't have a user account set up to log into. We ...
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How does VXLAN prevent duplicate MAC addresses?

It seems to me that VXLAN network identifier(VNI) works silimar to a prefix keeping identical MAC addresses on different VXLAN segments separate, so that they can coexist without duplication issues. ...
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VXLAN format details

Learning about VXLAN I found in a document: ...VTEP1 then adds a VXLAN header that contains the VNI to the Ethernet frame, encapsulates the frame in a Layer 3 UDP packet, and routes the packet ...
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516 views

Is it possible to isolate a network device from the rest of the LAN via its MAC address ?

Is it possible to isolate a network device from the rest of the LAN via its MAC address ? Im familiar with creating a VLAN based on a tagged port of the network switch, but is it possible by ...
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790 views

KVM guest not reaching externally (OVH, failover IPs)

Both host and guest are running Fedora 26 server edition. Host is from OVH, guest is ISO from Fedora directly. I've trimmed anything regarding TXRX and loopbacks for the sake of brevity. Main IP a.a....
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Linux easy way to extract MAC address per device

I am dealing with post systemd crapstorm where devices get renamed to eno1,2,3 or sometimes rename1,2,3. I don't run systemd as init system but unfortunately udevd is that systemd infected garbage ...
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Mac address not entering mac table of a huawei s5700 switch

We have a very strange problem, where certain ports refuse to learn the mac addresses of their hosts. For example host A is connected to switch S1 on port 0/0/30. Each packet to host A results in a ...
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Windows Server 2012 DHCP Failover and MAC address replication

I'm stuck with a problem in my configuration. We have a domain controller who works also as DNS and DHCP server. Yesterday i deployed a secondary DHCP server and configured it in a failover cluster ...
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how to answer a who has arp request

Ok this is a stupid question i know, but bear with me. I started a new job and the networking is terrible, there are a bunch of dumb switches on top of dumb switches. We are running a 10. network ...
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Hyper V External Switch MAC Address Spoofing

I am trying to replace a layer 2 VPN physical server with a Hyper V virtual machine, but it doesn't look like packets are making it out of the virtual server. Does Hyper V stop spoofed MAC address ...
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301 views

Resolve MAC address to vendor BASH

As the title states, I was wondering if I could resolve a MAC address to a vendor on Linux, with BASH. I would rather not use NMap, as I want it to be quick. Example: e0:b9:e5:9e:59:00 -> ...

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