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molik
Asked: 2021-08-10 00:42:00 +0800 CST

One interface take all the IP addresses and the other one use none

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I built my first custom kernel and have a few problem with it (see this other post).

I configured with /etc/network/interfaces one ip address on each physical interface of the computer. The commande ip a show the IP addresses on each interfaces.

debian@debian:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp7s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 64:70:02:11:67:a4 brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.1/24 brd 192.168.5.255 scope global enp7s0
       valid_lft forever preferred_lft forever
    inet6 fe80::6670:2ff:fe11:67a4/64 scope link
       valid_lft forever preferred_lft forever
3: enp0s25: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 00:1c:c0:94:71:d1 brd ff:ff:ff:ff:ff:ff
    inet 192.168.5.2/24 brd 192.168.5.255 scope global enp0s25
       valid_lft forever preferred_lft forever
    inet6 fe80::21c:c0ff:fe94:71d1/64 scope link
       valid_lft forever preferred_lft forever
debian@debian:~$

debian@debian:~$ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug enp7s0
#iface enp7s0 inet dhcp
iface enp7s0 inet static
address 192.168.5.1/24


allow-hotplug enp0s25
#iface enp0s25 inet dhcp
iface enp0s25 inet static
address 192.168.5.2/24


debian@debian:~$

enp0s25 = intel interface enp7s0 = realtek interface

The problem is the following :

  • When I connect an ethernet cable to the intel interface (driver e1000e), i can ping both ip addresses (even if the other interface is down).

  • When I connect an ethernet cable to the realtek tp-link interface (driver r8169), i can't ping any of the ip addresses (including the IP associated to it). The interface goes up when a cable is connected to it.

I searched a bit and I can't find a similar problem to mine. Do you know why there is a difference between what linux is prompting and what really happen with the interfaces ?

Edit : The problem is not related to the custom kernel, it also appear in the default Debian 4.19 kernel version. But they were working like a charm with a with a PfSense.

Edit 2 : The current route table (can change after the networking service is restarted and the realtek interface is upped before the intel interface).

debian@debian:~$ ip route
192.168.5.0/24 dev enp0s25 proto kernel scope link src 192.168.5.2
192.168.5.0/24 dev enp7s0 proto kernel scope link src 192.168.5.1
debian@debian:~$
debian interface

0 Answers