netplan and post-up/pre-down scripts

Mike Pontillo mike.pontillo at
Tue Feb 14 07:35:55 UTC 2017

Hi Seth,

Sorry for the delayed responses on this thread (this is a side project of

On Thu, Jan 12, 2017 at 7:57 PM, Seth Arnold <seth.arnold at>

> Is this a manifestation of the bridge trying to do spanning tree protocol?
> Most of the walkthroughs I've read lately about bridged networking include
> commands to turn off STP before they start adding ports to the bridge.

My present workaround is a /etc/network/interfaces file whose bridge looks
something like this:

iface wan0 inet manual
    metric 5000
    bridge_ports enp1s0
    bridge_stp off
    bridge_waitport 0
    bridge_fd 0
    post-up run-one /root/ifmonitor enp1s0 &
    pre-down kill $(cat /run/ifmonitor.enp1s0) 2> /dev/null || true

So no, this particular issue isn't related to the spanning-tree
configuration. (That part was unchanged when I was seeing the 5-minute

The 5-minute timeout was an issue with the interface set to 'auto' and the
DHCP configuration present in /e/n/i. I had to replace that with the
post-up script which manually monitored the interface and launched (or
killed) the DHCP client to get the behavior I wanted (no 5-minute timeout
of the WAN interface was disconnected or didn't respond to DHCP).

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