1. Q: I want to use ifplugd with my PCMCIA device, but ifplugd quits
when it doesn't find eth0, when I have not inserted the card. What
can I do?
A: Use the -f switch. This is not very clean however, since
modprobe is called on each cable detection query of ifplugd to
load a module for the network device. This is suboptimal. You
should probably run ifplugd only when the card is really inserted.
2. Q: I am using the -f switch, but the kernel logs are getting
filled with messages like "modprobe: modprobe: Can't locate module
eth0". What can I do?
A: Make sure you have a line like alias eth0 off in your
3. Q: When the cable is unplugged and the interface shut down it is
still available with ifconfig and markes as UP. Why this?
A: ifplugd cannot detect the link beat with a shut down interface
on certain (most as of kernel 2.4.19) network drivers. Thus
ifplugd enables the interface before querying the link status.
This may be switched off with -a flag. You might want to use it if
you have a sane network driver (e.g. eepro100). The subdirectory
patches/ in the ifplugd distribution includes a patch for the
8139too 0.9.26 driver, which makes the driver compatible with -a.
Don't ask me how to apply this patch. If you don't know, you won't
4. Q: Does it work with anything else than plain ethernet or wireless
A: Certainly not, since the MII and ETHTOOL ioctl()s and the
wireless extension don't exist on other network device types.
5. Q: I have a Realtek 8139 based network card. Everytime ifplugd
starts on bootup my machine freezes. What can I do?
A: This is a bug in the 8139too driver 0.9.25 (at least) shipped
with Linux 2.4.19, please upgrade to 8139too 0.9.26 (Linux 2.4.20
or seperately at
6. Q: There are already laptop-net's ifd and miid, why did you write
your own daemon?
A: laptop-net was too integrated with its profile system and
didn't work on my hardware when I had a look on it. It seemed
easier to me to write a simple but feature complete replacement
than using laptop-net without most of the special features
disabled. I didn't know about miid when I wrote ifplugd, but in
any case ifplugd is much better than miid. For a comparison of
miid and ifplugd, have a look on
7. Q: I have two interfaces (e.g. WLAN and copper ethernet), both
controlled by ifplugd, and want to force the network traffic to go
over the faster one of them, in case both are available at the
same time. How can I do this?
A: A tool I wrote called ifmetric might be exactly what you're
Lennart Poettering <mzvscyhtq (at) 0pointer (dot) de>, June 2005
$Id: README.html.in 124 2005-06-04 19:22:59Z lennart $