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ok linux jedis...this one is killing me .

I am running ubuntu server 16.04

i have 2 nic adapters with the same mac address. they keep getting assigned the same ip address by my router which is causing issues when I try to start a vnc server on these machines.

these machines also connect through the same switch before getting to the router. it looks like the dhcp process happens before I am spoofing the mac address.

here are links to my failed attempts l...ill try to update later why they failed...

no Setting permanent MAC address in Ubuntu 14.04 no How do I change / spoof my MAC address and easily switch between multiple ones?

no http://xmodulo.com/spoof-mac-address-network-interface-linux.html

no... https://ubuntuforums.org/showthread.php?t=2353448

this solution the closest as none of the other would take

closest working solution shows a different mac address when running ifconfig

I've attempted to spoof before ip is assigned by modifying /etc/network/interfaces

Auto eth1

Iface eth1 inet dhcp

hwaddress ether 00:01:02:03:00:12

reboot returns me to the same address

trying this... dhclient -r

followed by

dhclient eth1

this still returns the same ipaddress

if I run

ethtool -e eth1

I see the first address returned is the ip address

if I could edit or write the prom how would i go about doing this?

help me obiwan

Teeeravis
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2 Answers2

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It's the router that is confusing things for you. Options:

  • Set reserved IP addresses, by hostname, on the router

  • Set static IP addresses on the devices from the non-DHCP pool IP address range

  • Replace one of the devices

Andy Anderson
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A MAC address is built into the NIC hardware and is unique to that individual board. That is, no other network card on the Planet has the same MAC address.

True, the MAC address can be "spoofed" but why would one want to do that?

Switches communicate at the MAC address level. If two NICs on the same LAN have the same MAC address that will obviously cause problems. Ditto for any device using arp, dhcp and other protocols.

The problem, as you described it, sounds like it is self inflicted.

jones0610
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    mac addresses are the same for both nics...it can happen...i Think these nics doesn't get fused when they left the factory... title explains it...not self inflicted...spoofing a different address for only one of the nics... – Teeeravis Jul 08 '17 at 04:18