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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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Port security on a cisco switch - predefined source MAC address and maximum number of MAC addresses [migrated]

With port security on a Cisco switch, if you configure 1 source MAC address, does that also set the maximum MAC addresses to only one?
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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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1answer
60 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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1answer
74 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
69 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
139 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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2answers
134 views

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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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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209 views

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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125 views

Physical interface MAC send an ARP reply instead of the virtual

I have a similiar problem as described here. I want to achieve, that my virtual interface does a arp response and the other hosts on the subnet have the virtual mac address in their arp cache, not the ...
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30 views

Cannot ping specific DVR on network

I have a WatchGuard firewall as our firewall/router, windows server 2008 R2 standard for DHCP, 2 windows 10 machines and a Hikvision DVR. Machine 1 could see the cameras no problem for about a week ...
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Disallow devices connected to a PAN while allowing the parent device (Windows 10 Mobile Hotspot)

Yeah, it's a wordy title for an oddly specific question. What I'm trying to do is disallow devices connected via the Windows 10 mobile hotspot, while still allowing the device that created the ...
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1answer
473 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
2k 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
461 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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3answers
112 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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1answer
168 views

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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1answer
333 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 ...
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2answers
90 views

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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0answers
52 views

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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1answer
124 views

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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1answer
57 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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1answer
255 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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1answer
703 views

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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1answer
386 views

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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667 views

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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3answers
2k views

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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0answers
234 views

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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1answer
175 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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0answers
24 views

Why are there different types of bond configuration policies in linux, instead of one that can give a combined throughput and fail-over configuration?

I am confused and not able to understand exactly the actual concept behind it. At switch level, what happens that prevents to use one globally accepted bond configuration policy? And I don't ...
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1answer
131 views

How can I create a top priority firewall rule for a trusted mac address?

I want to accept all packets sent to my centos7 VPS from my device regardless of options defined on public zone. (I want to remove ssh service from public zone and just be able to connect from my mac ...
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2answers
94 views

No network after MAC address change

I'm running a CentOS 5.4 box for which I need to spoof a MAC address in order to make a certain software work (nothing illegal going on, before you ask). Problem: Whenever I try to change the MAC, I ...
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2answers
1k views

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. ...
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1answer
2k views

Ubuntu 16.04, Keepalived VMAC

I'm trying to build up two redundant forward-facing load balancers (using either IPVS or NGINX), but first I'm trying to get the floating VRRP virtual-ip/mac to work properly before moving forward ...
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1answer
370 views

nftables configuration - allow mac on tcp port

im new in firewalls etc. readed nftables quick reference how to allow only my mac address (my device - laptop, phone etc.). allow my mac to access ssh port (port:22) tried that: ether saddr 00:00:...
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2answers
2k 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 ...
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4answers
95 views

Getting a Windows machine's MAC address

OK guys, this is not the usual easy to answer question the title may imply... I need to get the MAC address from a machine running Windows (ranging from XP to Server2012). I have the following option ...
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1answer
527 views

arp broadcast responds with several different MACs for same IP

I'm experiencing an issue that's causing a lot of problems on our LAN. I have a Windows Server with a single NIC, 192.168.0.100 I have certain services running on the server that I am having ...
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0answers
46 views

Is it possible to create a second network device with a specific name?

Due to a licence server requirement I need to have an eth0 or eth1 named network device. However, my current configuration only has a network device named enp8s0. I am using a CentOS 7 linux system. ...
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0answers
596 views

arp table contains addresses asigned to 00:00:00:00:00:00 mac address

What mean 00:00:00:00:00:00 MAC address in arp table? On my OpenWRT router on interface connected to ISP I have seen 24 entries with this MAC address and on local network there are 7 entries. What ...
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1answer
4k views

Can't ping gateway after upgrading to Ubuntu 16.04 | arp issue?

After upgrading to Ubuntu 16.04 from 14.04 I can't ping gateway, at first interface eth0 wasn't starting up, and I read that refreshing new mac address would fix that, so I decided to remove the ...
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1answer
480 views

Spacewalk/Cobbler system with multiple interfaces/MAC

I have bare metal provisioning set up with a DHCP/PXE server and a Spacewalk server. I'm using cobbler system records to match a machines MAC address to the system profile. Basically: cobbler ...
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1answer
2k views

How to view dnsmasq client MAC addresses dynamically?

If I have already known the client IP, I know there's /var/log/dnsmasq.log and it contains logs such as Jun 13 12:22:42 dnsmasq-dhcp[499]: DHCPACK(wlan0) 172.24.1.110 34:12:98:11:80:bd ones-iPad ...
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1answer
3k views

How to get the correct MAC address of Windows Server 2008 out of multiple MAC addresses?

I want to know the unique MAC address of my Windows Server 2008 R2. When I used getmac command in command prompt I got a list of MAC addresses(6 count) under Primary Address header. Could you please ...
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1answer
598 views

“match hardware” in dhcpd.conf not working

I've been trying to get mac addresses with a certain OUI into a certain address pool. I haven't been able to get it to work at all. Here is a snippet of my dhcpd.conf and how it's applied. class "...
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107 views

Netgear Prosafe SRX5308 config with Virgin Superhub

We have just bought a Netgear Prosafe SRX5308 to provide load balancing with our 4 internet connections, but I am struggling to get it configured with our Virgin Media connection. The auto-detect ...
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1answer
188 views

iwconfig and arp commands report slightly different MAC addresses

I'm at a wifi hotspot where, when I look up the router's MAC address by two different methods, I get slightly different results: $ arp -a ? (10.128.128.128) at 00:18:0a:58:WX:YZ [ether] on wlan0 ? (...
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1answer
710 views

Does a private MAC Address range exist?

I need a set of MAC/Ethernet addresses that I do not have to worry about collisions with, analogous to 192.168.x.x: addresses that will NEVER be assigned to real hardware.
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1answer
391 views

How to create DHCP reservations with long hardware address?

DHCP is managed by a Windows 2008r2 server. I want to convert a lease into a reservation so the IP will be fixed. Normally, I create a reservation based on the assigned IP address, and when the lease ...
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2answers
133 views

Guest VMs cant reach each other on Different ESXi Servers

I have two vSphere EXSI 6 servers both setup with the same vSwitchs and connected to the same physical switches Server 1: eth0 => vlan143 (mapped to CORE/Management vSwitch) eht1 => vlan140 (...