eBPF Security: Kernel-Level Monitoring, Network Filtering, and Runtime Protection
Part of the Cybersecurity Skills Guide — This article is one deep-dive in our complete guide series.
By HADESS Team | February 28, 2026 | Updated: February 28, 2026 | 5 min read
eBPF (extended Berkeley Packet Filter) runs sandboxed programs in the Linux kernel without modifying kernel source or loading kernel modules. For security, this means deep visibility into system behavior — every system call, network connection, file access, and process execution — with minimal performance overhead. It is the foundation of modern Linux runtime security tools.
How eBPF Works for Security
eBPF programs attach to kernel hooks — tracepoints, kprobes, network events, LSM hooks — and execute when those hooks fire. The kernel verifier ensures eBPF programs cannot crash the kernel, access arbitrary memory, or loop infinitely. This safety model allows production deployment of custom instrumentation without the risks of kernel modules.
Security-relevant attachment points:
- Tracepoints for system call monitoring (syscall enter/exit)
- Kprobes/kretprobes for function-level instrumentation
- LSM hooks for security policy enforcement (file access, network, capability checks)
- TC (Traffic Control) and XDP (eXpress Data Path) for network filtering
- Uprobe for user-space function tracing
Kernel-Level Monitoring
eBPF-based monitoring sees everything that happens on a system. Unlike user-space agents that rely on log files or /proc polling, eBPF captures events at the source.
Process execution monitoring tracks every execve call, capturing the binary path, arguments, parent process, and user context. This catches malicious binaries, living-off-the-land techniques, and unauthorized process execution.
File access monitoring through eBPF programs attached to VFS (Virtual File System) operations records every file open, read, write, and permission change. Detect sensitive file access — /etc/shadow, SSH keys, database files — in real time.
Network connection tracking captures every TCP/UDP connection with source, destination, port, and the process that initiated it. Map network behavior to processes without relying on netstat or ss snapshots. Detect unexpected outbound connections, lateral movement, and data exfiltration.
Tools built on eBPF for security monitoring:
- Tetragon (by Cilium/Isovalent) — runtime security enforcement with process, file, and network visibility
- Falco (with eBPF driver) — runtime threat detection using rules
- Tracee (by Aqua Security) — runtime security and forensics
- bpftrace — high-level tracing language for ad-hoc investigation
Network Filtering
XDP processes packets at the earliest possible point — before the kernel network stack allocates an sk_buff. This enables wire-speed packet filtering, DDoS mitigation, and load balancing.
XDP programs can:
- Drop malicious packets before they consume kernel resources
- Redirect traffic between interfaces for transparent proxying
- Implement custom firewalling logic based on packet contents
Cilium uses eBPF for Kubernetes network policies, replacing iptables with programmable network filters. eBPF-based network policies operate at Layer 3-7, enabling identity-aware filtering. A pod’s network policy can reference Kubernetes labels and service identities rather than IP addresses, which are ephemeral in container environments.
For traditional Linux servers, eBPF-based firewalling through TC programs provides dynamic filtering that adapts to runtime conditions without reloading iptables rules.
Runtime Security
eBPF enables enforcement, not just detection. Using LSM (Linux Security Module) hooks, eBPF programs can deny operations in real time:
- Block execution of unsigned binaries
- Prevent processes from accessing files outside their expected paths
- Deny network connections to unexpected destinations
- Enforce capability restrictions beyond what Linux capabilities provide
Tetragon implements this enforcement model. Define policies that specify expected process behavior — which binaries should run, which files they should access, which network connections they should make. Tetragon enforces these policies at the kernel level, killing processes that violate them.
This approach supplements container security. Even if an attacker escapes to the host, eBPF-based enforcement at the kernel level can detect and block malicious actions.
Performance Tracing
eBPF is also used for security-relevant performance analysis. Identify why a security tool is causing latency, trace TLS handshake performance, or measure the overhead of your endpoint agent.
bpftrace one-liners for quick investigation:
“bash
Trace all files opened by a specific process
bpftrace -e 'tracepoint:syscalls:sys_enter_openat /comm == "suspicious"/ { printf("%s %s\n", comm, str(args->filename)); }'
Count system calls by process
bpftrace -e 'tracepoint:raw_syscalls:sys_enter { @[comm] = count(); }'
“
Related Career Paths
eBPF expertise maps to Security Engineer and Linux specialist career paths. As runtime security tools increasingly use eBPF, understanding the underlying technology differentiates engineers who can troubleshoot and extend these tools.
Next Steps
- Assess your Linux and kernel security knowledge with the skills assessment
- Browse the skills library for container runtime and Linux security topics
- Use the coaching tool to build a hands-on eBPF learning plan
Related Guides in This Series
- Blockchain Security: Smart Contract Auditing, DeFi Exploits, and Wallet Safety — HADESS | 2026
- Applied Cryptography: Algorithms, TLS, Key Management, and Common Pitfalls — HADESS | 2026
- Smart Contract Security: Solidity Vulnerabilities, Reentrancy, and Auditing
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Frequently Asked Questions
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HADESS Team consists of cybersecurity practitioners, hiring managers, and career strategists who have collectively spent 50+ years in the field.
