Hello Florian, I found the issue. You are right, there is no synproxy in 4.1. Yet, it still hits that switch case and tries to validate it as u32 type and then fails. Good thing that the vendor distributes kernel sources in their forum. They have modified ctattr_type and appended a new attribute: CTA_MARK2_64. This clashes with CTA_SYNPROXY. Never imagined something like this would ever happen. I used the libmnl example and parsed the netlink message myself. It works. Thank you! I was able to find the issue based on your clue. Have a great weekend. On Sat, May 22, 2021 at 5:14 AM Florian Westphal <fw@xxxxxxxxx> wrote: > > Psyspy 22 <psyspy2020@xxxxxxxxx> wrote: > > Hello Pablo, > > > > I cross compiled the application. Host/Build: Ubuntu 20,10, x86_64. > > Target machine: aarch64, Linux kernel: 4.1. > > 4.1? There is no synproxy support in that version. > > Are you passing unitialised garbage data to the library by mistake?
