[Cialug] How is this possible?

[Barry Ahsen]

You say “The built in network card should be eth0,” but your BIOS, kernel modules, or udev might not agree. 

If you boot with the onboard NIC connected, and it shows up as eth1, the above might be the case, and you can override it several ways (in the BIOS, modprobe, or in the interface configuration)

If eth0 moves with the network cable, it’s probably NetworkManager, systemd or some other software being “helpful”


-barry






On 3/30/17, 3:37 PM, "Tom Sellers" <cialug-bounces at cialug.org on behalf of tsellers2009 at gmail.com> wrote:

    I have a small desktop computer with two wired network connections.  One is
    built into the motherboard and the other is a 3com network card that I have
    added.
    
    The built in network card should be eth0 and the added card should be
    eth1.  The eth0 wired connection is set to use dhcp while the eth1 wired
    network card is assigned an IP.
    
    When I boot the system up with no network cable connected to eth0 and a
    cable to my dhcp network on eth1and run ifconfig. I get a display that
    indicates eth0 has an IP on my dhcp network and eth1 shows the assigned ip
    given it.
    
     When I ping the dhcp network address I get a response and when I ping the
    assigned IP I also get a response.  Both appear to be using the added
    network card (eth1) even though the two network connections show separate
    hardware addresses.
    
    Can anyone explain how this is possible?
    
    This all started when I was unable to get linux to get a dhcp address on
    eth0 with both network jacks cabled to their respective networks.  I didn't
    think the same card could have two separate IP addresses.
    
    Not that familiar with linux!
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