-----Original Message-----
From: Brenden Blanco [mailto:bblanco@...]
Sent: Friday, March 4, 2016 10:09 PM
To: O Mahony, Billy <billy.o.mahony@...>
Cc: Daniel Borkmann <daniel@...>; iovisor-dev@...
Subject: Re: [iovisor-dev] unknown func 13

On Fri, Mar 4, 2016 at 10:01 AM, O Mahony, Billy <billy.o.mahony@...>
wrote:

Hi Daniel, Brendan,

Thanks for the tips. Unless what I'm trying to do just won't work I'll stick

with kernel 4.4 and the ingress qdisc for now.

So I changed my bpf programs to look like this:
6 int eth1_ic(struct __sk_buff *skb) {
7 bpf_trace_printk ("eth1_ic\n");
8 bpf_redirect(5, 0);
9 return TC_ACT_REDIRECT;

That's fine, it'll still work.

However, I still don’t see packets being received by the traffic generator I

have attached to eht1 and eth3.

If I also run BPF.trace_print in a separate console (actually hello_world.py) I

can see the trace statements but not at anything like the rate that I
configured the traffic generator to generate packets (100pkts/sec). Also if I
vary the rate of traffic ingress on the eth1/3 the ratio of the corresponding
trace lines does not change - so not sure what is going on there.

Probably arp is failing, your generator is probably doing nothing because it
can't resolve the other side.

avahi-daemon-1006 [031] ..s. 10942.915221: : eth1_ic
avahi-daemon-1006 [031] ..s. 10943.100833: : eth1_ic
avahi-daemon-1006 [031] ..s. 10943.182141: : eth3_ic
avahi-daemon-1006 [031] ..s. 10943.801170: : eth1_ic
avahi-daemon-1006 [031] ..s. 10944.375068: : eth3_ic
avahi-daemon-1006 [031] ..s. 10944.560597: : eth3_ic

BTW my tc filter output looks like so:

$ tc filter show dev eth3 parent ffff:
filter protocol all pref 49152 u32
filter protocol all pref 49152 u32 fh 800: ht divisor 1 filter
protocol all pref 49152 u32 fh 800::1 order 1 key ht 800 bkt 0 flowid 1:2
match 00000000/00000000 at 0
action order 1: gact action pass
random type none pass val 0
index 10 ref 1 bind 1

Is your iproute2 up to date? This usually misses showing the bpf program
since it doesn't understand the flags. If you can build
iproute2 from source, preferably from the net-next branch, you will see
more useful information. I would also include "tc -s" in the output so you can
see drops/passes.

If you are in fact using the latest iproute2, then the above filters are wrong. It
should look more like this:

filter protocol all pref 49152 u32
filter protocol all pref 49152 u32 fh 800: ht divisor 1 filter protocol all pref
49152 u32 fh 800::1 order 1 key ht 800 bkt 0 flowid 1:2
match 00000000/00000000 at 0
action order 1: bpf on_packet default-action pass
index 1 ref 1 bind 1 installed 0 sec used 0 sec
Action statistics:
Sent 112 bytes 2 pkt (dropped 0, overlimits 0 requeues 0)
backlog 0b 0p requeues 0

Thanks again,

Billy.