id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
469	airbase-ng MTU problems	hdm@…		"I finally figured out the root cause behind the following error message:
{{{
write failed: Message too long
wi_write(): Illegal seek
}}}

What happens:
 * airmon-ng creates a new monitor VAP with the same MTU as the master interface (1500)
 * airbase-ng creates a new TUN/TAP interface with the same MTU (1500)
 * a packet gets sent through the TUN/TAP thats close to max frame size
 * airbase-ng sticks the injection header on it and writes it to the card
 * the card sees a frame larger than the configured MTU and rejects it
 * the error message above is printed and the packet is dropped
 * the guy writing the app using the TUN/TAP interfaces swears alot :-)

The workaround is to increase the MTU of the master interface or decrease the MTU of the TUN/TAP. The MTU of the monitor mode interface should be the cards max (~2300?), while the MTU of the TUN/TAP should still be the normal ethernet max (1500 ~ 1518/1522). Setting the MTU manually fixes the problem."	defect	closed	minor	1.0	airbase-ng	1.0-dev	fixed