A quick demo of BPF XDP program to drop packet, sample code here:[ Ссылка ]
/*
* Sample XDP/tc program, sets the TCP PSH flag on every RATIO packet.
* compile it with:
* clang -O2 -emit-llvm -c tcp_ack.c -o - |llc -march=bpf -filetype=obj -o tcp_ack.o
* attach it to a device with XDP as:
* ip link set dev lo xdp object tcp_ack.o verbose
* attach it to a device with tc as:
* tc qdisc add dev eth0 clsact
* tc filter add dev eth0 egress matchall action bpf object-file tcp_ack.o
* replace the bpf with
* tc filter replace dev eth0 egress matchall action bpf object-file tcp_ack.o
*/

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