Hi guys, it's my first post here

I've got wlan0 connected to the internet, and it routes packets (nat & forwarding) between two adapters: eth0 and ap0. I need to set priority eth0 (much) over ap0... I just need to do something like packets from and to eth0 are forwarded instantly, and packets from and to ap0 allways must wait and use as much bandwidth as is free. But i don't know how :/
I draw the topology here:
http://i.imgur.com/A6TMxL1.png

I read that it's related to the tc command, but i don't understand these tutorials... Please help me guys

You can set shaper of HTB format. That is easy to understand. The rate of over ap0 is 0, that means the traffic only use the bandwidth that eth0 left over.

Read this - http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm

Then try someting like this -

Configure an HTB Q outbound on wlan0

$ tc qdisc add dev wlan0 root handle 1: htb default 3


Define the traffic you want to be given preferential treatment (i.e. traffic from eth0-

$ tc filter add dev wlan0 protocol ip parent 1:0 prio 1 u32 \
match ip src 1.2.3.4 flowid 1:1


Create a class encompassing all traffic set to match your outbound bandwidth via wlan0-

$ tc class add dev wlan0 parent 1: classid 1:1 htb rate 1000kbps


Create a sub-class defining the htb bandwidth assigned to your special traffic -

$ tc class add dev wlan0 parent 1:1 classid 1:2 htb rate 990kbps ceil 1000kbps


Create the default sub-class ( 3 as assigned in the first command) defining the bandwidth guaranteed to everything else -

$ tc class add dev wlan0 parent 1:1 classid 1:3 htb rate 10kbps ceil 1000kbps


Check out the results -

$ tc qdisc show dev eth0