How eBPF Intercepts Packets Before Kernel Routing
eBPF programs redirect packets at XDP or TC hooks before the kernel routing table is consulted, causing routing confusion when troubleshooting.
Category: eBPF in OpenWRT
Capture Packets in OpenWRT with eBPF
I build and flash custom firmware so I can run a practical OpenWRT eBPF packet capture on small routers without guessing. I focus on concrete steps: kernel config flags, compiling from source, and verifying support with bpftool. I explain three workable capture paths: quick XDP loads via iproute2 or xdp-tools, debugfs prints using bpf_trace_printk, and […]
Build BPF Toolchain on OpenWRT
I set a single goal: build an OpenWRT eBPF toolchain end to end—compile, flash, and verify on real hardware with no guesswork. I explain the steps I use: enable CONFIG_BPF, CONFIG_BPF_SYSCALL, CONFIG_NET_CLS_BPF, and CONFIG_NET_ACT_BPF in the kernel via make menuconfig. Then I install build deps on my Linux host, clone the official repo, and run […]
XDP Firewall on OpenWRT: Early Packet Drop at Line Rate
XDP intercepts packets in the driver before the kernel allocates buffers, enabling high-volume DDoS mitigation and load balancing with minimal CPU cost.
OpenWrt eBPF Kernel Setup: Which Options to Enable
Build OpenWrt with working eBPF support by enabling the right kernel symbols, matching options to XDP, tc, tracing, or BTF, and checking JIT support.