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I use a Ubuntu-arm, uname -a

Linux arm 3.7.8-x8 #1 SMP Sat Feb 16 04:15:13 UTC 2013 armv7l armv7l armv7l GNU/Linux

I have two USB WiFi interfaces that are named wlan0 and wlan1 on /etc/udev/rules.d/70-persistent-net.rules

I run a script on each start-up that does:

ifdown wlan0 
rm /var/run/wpa_supplicant/wlan0
ifup wlan0
wpa_supplicant -B -Dnl80211 -iwlan0 -c/etc/w.conf

ifdown wlan1
rm /var/run/wpa_supplicant/wlan1
ifup wlan1
wpa_supplicant -B -Dnl80211 -iwlan1 -c/etc/w2.conf

sometimes one of the interface is named as rename5 whereas the other interface is named according to the 70-persistent-net.rules.

Could anyone explain why it is named rename5 instead of wlan0 or wlan1 and how can I prevent that thing to happen?

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up vote 4 down vote accepted

Though not completely certain, I believe the root of your problem (which I too had to face, albeit on a different architecture) is this kind of bugs to which udev is prone. The important part of that post is where udev's developers state:

We do no longer support renaming network interfaces in the kernel namespace. Interface names are required to use custom names that can never clash with the kernel created ones.

We do not support swapping names; we cannot win any race against the kernel creating new interfaces at the same time.

We do no longer support the creation of udev rules from inside the hotplug path.

And later in the same post:

Predictable network interface names require a tool like biosdevname, or manually configured names, which do not use the kernel names.

Both the bit about names not clashing with kernel names and that not supporting swapping names I believe apply to you.

While I cannot diagnose your system from afar, I think a good initial try might be choosing very different names, like nic1 and wifi-nic2.

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