And confirmed, starting with a high packet number results in a very short testbed run, 296 packets and then nothing, just as you surmised. Sorry for raising the alarm falsely. Looks like I need to roll my own build of wpa_supplicant as the ubuntu builds don't include the macsec driver, haven't tested Gentoo's ebuilds yet to see if they do.
Josh Coombs On Sun, Oct 14, 2018 at 4:52 PM Josh Coombs <jcoo...@staff.gwi.net> wrote: > > On Sun, Oct 14, 2018 at 4:24 PM Sabrina Dubroca <s...@queasysnail.net> wrote: > > > > 2018-10-14, 10:59:31 -0400, Josh Coombs wrote: > > > I initially mistook this for a traffic control issue, but after > > > stripping the test beds down to just the MACSec component, I can still > > > replicate the issue. After approximately 5TB of transfer / 4 billion > > > packets over a MACSec link it stops passing traffic. > > > > I think you're just hitting packet number exhaustion. After 2^32 > > packets, the packet number would wrap to 0 and start being reused, > > which breaks the crypto used by macsec. Before this point, you have to > > add a new SA, and tell the macsec device to switch to it. > > I had not considered that, I naively thought as long as I didn't > specify a replay window, it'd roll the PN over on it's own and life > would be good. I'll test that theory tomorrow, should be easy to > prove out. > > > That's why you should be using wpa_supplicant. It will monitor the > > growth of the packet number, and handle the rekey for you. > > Thank you for the heads up, I'll read up on this as well. > > Josh C
