src/tech/datausage/kernel-changes.md

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This is a summary of the main changes in the kernel that diverge from mainline.

* added net/netfilter/xt_qtaguid*
* imported then modified net/netfilter/xt_quota2.c from xtables-addons project
* fixes in net/netfilter/ip6_tables.c
* modified ip*t_REJECT.c
* modified net/netfilter/xt_socket.c

A few comments on the kernel configuration:

* xt_qtaguid masquerades as xt_owner and relies on xt_socket and itself relies on the connection tracker.
* The connection tracker can't handle large SIP packets, it must be disabled.
* The modified xt_quota2 uses the NFLOG support to notify userspace.