Hi,
I'm using busybox with ENABLE_FEATURE_IFUPDOWN_IP and when using
ifdown with a virtual interface it takes down the primary interface as
well. For our board we setup eth0:0 on a 10.10.10.x/29 network and
using ifup eth0:0 does the following:
ip addr add 10.10.10.9/29 dev eth0:0 label eth0:0
ip link set eth0:0 up
run-parts /etc/network/if-up.d
and ip addr show gives us
...
2 : eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UP group default qlen 1000
link/ether a0:f6:fd:18:2b:13 brd ff:ff:ff:ff:ff:ff
inet 172.27.105.10/22 brd 172.27.107.255 scope global eth0
valid_lft forever preferred_lft forever
inet 10.10.10.9/29 scope global eth0:0
valid_lft forever preferred_lft forever
inet6 fe80::a2f6:fdff:fe18:2b13/64 scope link
valid_lft forever preferred_lft forever
Taking it down runs
ip addr flush dev eth0:0
ip link set eth0:0 down
run-parts /etc/network/if-post-down.d
The problem is ip addr flush dev eth0:0 removes all ip addresses from
eth0. You can see this if you run
ip -stat -stat addr flush dev eth0:0
2: eth0 inet 172.27.105.10/22 brd 172.27.107.255 scope global eth0
valid_lft forever preferred_lft forever
2: eth0 inet 10.10.10.9/29 scope global eth0:0
valid_lft forever preferred_lft forever
2: eth0 inet6 fe80::a2f6:fdff:fe18:2b13/64 scope link
valid_lft forever preferred_lft forever
*** Round 1, deleting 3 addresses ***
*** Flush is complete after 1 round ***
To work around this I have added the following patch which adds a
label to the flush command so only flush the eth0:0 address:
As I'm no networking expert is this a valid fix? if not what's the
correct way to handle virtual interfaces.
I've also tried the switch to use ifconfig and this also fails for a
completely different reason and it's because you can't run 'if config
eth0:0 up' before using ifconfig eth0:0 10.10.10.9 etc.."
You get "SIOCSIFFLAGS: Cannot assign requested address". As it
attempts to run all commands you do actually get the interface and if
you run ifup eth0:0 again it will work. I see there is a reason for
running the commands in this order so I don't know what the fix would
be for this one.
Best Regards,
Martin.
Index: busybox-1.24.1/networking/ifupdown.c
===================================================================
--- busybox-1.24.1.orig/networking/ifupdown.c 2016-09-06
13:39:03.264378441 +0100
+++ busybox-1.24.1/networking/ifupdown.c 2016-09-06 13:39:59.288380571 +0100
@@ -501,7 +501,7 @@
{
int result;
# if ENABLE_FEATURE_IFUPDOWN_IP
- result = execute("ip addr flush dev %iface%", ifd, exec);
+ result = execute("ip addr flush dev %iface% [[ label %label%]]", ifd, exec);
result += execute("ip link set %iface% down", ifd, exec);
# else
/* result = execute("[[route del default gw %gateway% %iface%]]",
ifd, exec); */
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