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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681 views

Solaris doesn't know which MAC address to use to send an UDP multicast message

I have a pair of Solaris 10 boxes which are supposed to send multicast UDP packets to a group of hosts. One of them works just fine, whereas the other one does not. The problem with the second ...
3
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1answer
574 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
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1answer
465 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 ...
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1answer
334 views

Redirect traffic on port 80 into apache for unknown macs, and into squid for some macs

I have a linux box behaving like a router that handles two network interfaces: eth0 for internet and eth1 for LAN. I set up iptables in order to redirect all the web traffic coming by the LAN into a ...
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1answer
18 views

MAC ID Binding to IP on Windows

Is there a way i can bind a certain IP to have traffic allowed if it has a certain MAC ID on windows routing and remote access or network policies? Basically Associated MAC ID to IP xxx.xxx.xxx.xxx ...
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1answer
68 views

Does the IP -> Ethernet multicast address mapping ambiguity matter for IGMP snooping switches?

There are 2^28 possible IP multicast addresses, but only 2^23 possible Ethernet (MAC) multicast addresses (http://technet.microsoft.com/en-us/library/cc957928.aspx), which is why e.g. 224.1.1.1 gets ...
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1answer
70 views

Possible MAC conflict in ESX

I have two virtual machines that are 10.1.1.10 and 10.1.1.20 in an ESX. I try to access theses machines by another network 192.168.1.0/24. The problem is that when I can ping one machine, I can not ...
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1answer
2k views

Ping server NETBIOS name returns wrong IP and “Destination host unreachable”

Problem server is Windows 2008 R2 VM running on VMWare ESXi 4 host. Single network adapter manually assigned single IP address (192.168.1.11). When I ping the server from any other network computer, ...
2
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0answers
226 views

Keepalived failover not working for Static NAT target behind Cisco ASA

I've got a Cisco ASA[0] with a pair of Linux boxes in the DMZ running Keepalived and HAproxy acting as a load-balancing failover pair for another pair of Windows servers, also in the DMZ. I'm ...
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0answers
221 views

dhcpd.conf rule-based mapping

We have ~100 physical nodes which can host a large number of VMs apiece. We need to set up dhcpd on one machine to distribute addresses in a predictable fashion based on MAC address. We'd like to go ...
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12 views

Can't find IPMI mac address

The MAC address listed under ipmitool lan print seems to be incorrect, since there is no entry in the arp cache for the set ip address, 10.224.242.121: # arp 10.224.242.121 10.224.242.121 ...
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32 views

Wireless Client missing from MAC table

I am currently having problems with Wireless Clients loosing network connectivity, though still displaying a connection to their Wireless Access Point. I have 4 Wireless APs, each a Cisco WAP321 ...
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0answers
48 views

Do some network administrators assign MAC addresses with an unassigned OUI?

I am in a situation where I have observed MAC addresses on a network that do not belong to any assigned OUI range, and this is causing some issues. I suspect the cause here is a heavy use of ...
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0answers
37 views

Network access sometimes lost, disabling port security temporary solves?

I have network based primarily on Edge-Core managed switched. Port security with max mac count = 1 is enabled, DHCP snoopping enabled. Some clients have troubles with accesing network, but when I ...
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42 views

STP/RSTP: what switch should do with MAC table on a port after changing STP role of this port?

I have two switches and two active links between them. Spanning Tree Protocol is enabled on both devices, and port roles are assigned correctly: there are two Designated/Forwarding ports on RootSwitch ...
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0answers
74 views

How to detect on Linux that given MAC (HWaddr) is a virtual MAC and will change after rebooting?

Is it possible on Linux to detect automatically that given MAC (HWaddr in ifconfig output) is a virtual MAC and will change after rebooting. or alternatively is there a way to detect virtual network ...