Почему Linux продолжает использовать отключенные интерфейсы Ethernet?

ARP flux!

вы должны установить sysctl параметры arp_ignore и arp_announce к вашим потребностям.

Сначала проверьте эти команды, а затем, если они работают, вы можете добавить эти строки в /etc/sysctl.conf файл.

Сначала выполните эту команду:

# sysctl -a | grep net.ipv4.conf.*.arp

и результат должен быть примерно таким:

net.ipv4.conf.all.arp_accept = 0
net.ipv4.conf.all.arp_announce = 0
net.ipv4.conf.all.arp_filter = 0
net.ipv4.conf.all.arp_ignore = 0
net.ipv4.conf.all.arp_notify = 0
net.ipv4.conf.all.proxy_arp = 0
net.ipv4.conf.all.proxy_arp_pvlan = 0
net.ipv4.conf.default.arp_accept = 0
net.ipv4.conf.default.arp_announce = 0
net.ipv4.conf.default.arp_filter = 0
net.ipv4.conf.default.arp_ignore = 0
net.ipv4.conf.default.arp_notify = 0
net.ipv4.conf.default.proxy_arp = 0
net.ipv4.conf.default.proxy_arp_pvlan = 0
net.ipv4.conf.eth0.arp_accept = 0
net.ipv4.conf.eth0.arp_announce = 0
net.ipv4.conf.eth0.arp_filter = 0
net.ipv4.conf.eth0.arp_ignore = 0
net.ipv4.conf.eth0.arp_notify = 0
net.ipv4.conf.eth0.proxy_arp = 0
net.ipv4.conf.eth0.proxy_arp_pvlan = 0
net.ipv4.conf.eth1.arp_accept = 0
net.ipv4.conf.eth1.arp_announce = 0
net.ipv4.conf.eth1.arp_filter = 0
net.ipv4.conf.eth1.arp_ignore = 0
net.ipv4.conf.eth1.arp_notify = 0
net.ipv4.conf.eth1.proxy_arp = 0
net.ipv4.conf.eth1.proxy_arp_pvlan = 0
net.ipv4.conf.lo.arp_accept = 0
net.ipv4.conf.lo.arp_announce = 0
net.ipv4.conf.lo.arp_filter = 0
net.ipv4.conf.lo.arp_ignore = 0
net.ipv4.conf.lo.arp_notify = 0
net.ipv4.conf.lo.proxy_arp = 0
net.ipv4.conf.lo.proxy_arp_pvlan = 0

затем вы выполняете эти команды:

# sysctl -w net.ipv4.conf.all.arp_ignore=1
# sysctl -w net.ipv4.conf.all.arp_announce=2

по-прежнему выполните эту команду, чтобы проверить изменения

# sysctl -a | grep net.ipv4.conf.*.arp

и вы должны увидеть что-то подобное с изменениями:

net.ipv4.conf.all.arp_accept = 0
net.ipv4.conf.all.arp_announce = 1
net.ipv4.conf.all.arp_filter = 0
net.ipv4.conf.all.arp_ignore = 1
net.ipv4.conf.all.arp_notify = 0
net.ipv4.conf.all.proxy_arp = 0
net.ipv4.conf.all.proxy_arp_pvlan = 0
net.ipv4.conf.default.arp_accept = 0
net.ipv4.conf.default.arp_announce = 0
net.ipv4.conf.default.arp_filter = 0
net.ipv4.conf.default.arp_ignore = 0
net.ipv4.conf.default.arp_notify = 0
net.ipv4.conf.default.proxy_arp = 0
net.ipv4.conf.default.proxy_arp_pvlan = 0
net.ipv4.conf.eth0.arp_accept = 0
net.ipv4.conf.eth0.arp_announce = 0
net.ipv4.conf.eth0.arp_filter = 0
net.ipv4.conf.eth0.arp_ignore = 0
net.ipv4.conf.eth0.arp_notify = 0
net.ipv4.conf.eth0.proxy_arp = 0
net.ipv4.conf.eth0.proxy_arp_pvlan = 0
net.ipv4.conf.eth1.arp_accept = 0
net.ipv4.conf.eth1.arp_announce = 0
net.ipv4.conf.eth1.arp_filter = 0
net.ipv4.conf.eth1.arp_ignore = 0
net.ipv4.conf.eth1.arp_notify = 0
net.ipv4.conf.eth1.proxy_arp = 0
net.ipv4.conf.eth1.proxy_arp_pvlan = 0
net.ipv4.conf.lo.arp_accept = 0
net.ipv4.conf.lo.arp_announce = 0
net.ipv4.conf.lo.arp_filter = 0
net.ipv4.conf.lo.arp_ignore = 0
net.ipv4.conf.lo.arp_notify = 0
net.ipv4.conf.lo.proxy_arp = 0
net.ipv4.conf.lo.proxy_arp_pvlan = 0

Или вы можете изменить значения в соответствии с вашими потребностями:

arp_announce

arp_announce - INTEGER
    Define different restriction levels for announcing the local
    source IP address from IP packets in ARP requests sent on
    interface:
    0 - (default) Use any local address, configured on any interface
    1 - Try to avoid local addresses that are not in the target's
    subnet for this interface. This mode is useful when target
    hosts reachable via this interface require the source IP
    address in ARP requests to be part of their logical network
    configured on the receiving interface. When we generate the
    request we will check all our subnets that include the
    target IP and will preserve the source address if it is from
    such subnet. If there is no such subnet we select source
    address according to the rules for level 2.
    2 - Always use the best local address for this target.
    In this mode we ignore the source address in the IP packet
    and try to select local address that we prefer for talks with
    the target host. Such local address is selected by looking
    for primary IP addresses on all our subnets on the outgoing
    interface that include the target IP address. If no suitable
    local address is found we select the first local address
    we have on the outgoing interface or on all other interfaces,
    with the hope we will receive reply for our request and
    even sometimes no matter the source IP address we announce.

    The max value from conf/{all,interface}/arp_announce is used.

    Increasing the restriction level gives more chance for
    receiving answer from the resolved target while decreasing
    the level announces more valid sender's information.

arp_ignore

arp_ignore - INTEGER
    Define different modes for sending replies in response to
    received ARP requests that resolve local target IP addresses:
    0 - (default): reply for any local target IP address, configured
    on any interface
    1 - reply only if the target IP address is local address
    configured on the incoming interface
    2 - reply only if the target IP address is local address
    configured on the incoming interface and both with the
    sender's IP address are part from same subnet on this interface
    3 - do not reply for local addresses configured with scope host,
    only resolutions for global and link addresses are replied
    4-7 - reserved
    8 - do not reply for all local addresses

    The max value from conf/{all,interface}/arp_ignore is used
    when ARP request is received on the {interface}

Когда вы будете удовлетворены, вы должны добавить эти две строки в /etc/sysctl.conf

# cp /etc/sysctl.conf /etc/sysctl.confBKP

# echo "net.ipv4.conf.all.arp_ignore=1" >> /etc/sysctl.conf

# echo s"net.ipv4.conf.all.arp_announce=2" >> /etc/sysctl.conf

эти ссылки для справки:

Поток ARP

Использование ARP

Надеюсь на эту помощь.