Vincent Li <vincent.mc.li@xxxxxxxxx> writes: > On Mon, Mar 20, 2023 at 2:57 PM Vincent Li <vincent.mc.li@xxxxxxxxx> wrote: >> >> On Mon, Mar 20, 2023 at 10:15 AM Jesper Dangaard Brouer >> <jbrouer@xxxxxxxxxx> wrote: >> > >> > >> > On 20/03/2023 16.33, Vincent Li wrote: >> > > >> > > if I have a XDP based firewall to block ip access based on system >> > > localtime/wall time, is it still impossible like what mentioned here >> > > https://github.com/xdp-project/xdp-tutorial/issues/204#issuecomment-819419800? >> > > If so, is there any way to workaround this? >> > >> > You could use the BPF-helper named: bpf_ktime_get_tai_ns() >> > >> > See man clock_gettime(2). It is the same as CLOCK_TAI, which is >> > (currently) offset with 37 sec to CLOCK_REALTIME which is wall-clock. >> > > > sorry a follow-up question, the bpf_ktime_get_tai_ns will return time > as nano seconds, right? > I do not need the nanoseconds precision, I only need HH:MM like hours > and minutes of the day, for example 10:30 = 10 * 60 + 30 is good > enough, > any trick get that from bpf_ktime_get_tai_ns() Populate the time at latest midnight from userspace when installing the program and calculate offsets from that?