--- title: Watch a Hybrid Post-Quantum Handshake on the Wire –... description: A hands-on lab that builds a hybrid post-quantum IKEv2 VPN tunnel using two Docker containers running strongSwan. The tutorial walks through confirming ML-KEM... canonical: https://daily.dev/posts/watch-a-hybrid-post-quantum-handshake-on-the-wire-ipsec-series-part-4-rpovq4vpj twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Watch a Hybrid Post-Quantum Handshake on the Wire – IPsec Series, Part 4 | daily.dev og:description: A hands-on lab that builds a hybrid post-quantum IKEv2 VPN tunnel using two Docker containers running strongSwan. The tutorial walks through confirming ML-KEM... og:url: https://daily.dev/posts/watch-a-hybrid-post-quantum-handshake-on-the-wire-ipsec-series-part-4-rpovq4vpj og:image: https://api.daily.dev/og/posts/RPOvq4VpJ.png og:image:alt: Watch a Hybrid Post-Quantum Handshake on the Wire – IPsec Series, Part 4 og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Watch a Hybrid Post-Quantum Handshake on the Wire – IPsec Series, Part 4 **[Cisco](https://daily.dev/sources/cisco)** · 7 min read · 0 upvotes · 0 comments ## Summary A hands-on lab that builds a hybrid post-quantum IKEv2 VPN tunnel using two Docker containers running strongSwan. The tutorial walks through confirming ML-KEM availability, capturing packets with tcpdump, and running a side-by-side comparison of classical X25519 versus hybrid X25519+ML-KEM-768 handshakes. Key findings: the hybrid approach adds one extra IKE_INTERMEDIATE round trip (~1 ms overhead), requires IKE-layer fragmentation for the 1184-byte ML-KEM public key, but leaves IKE_AUTH packets byte-for-byte identical. The performance cost of going quantum-safe is negligible — roughly 1 ms and a couple of kilobytes of extra bandwidth. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Mutual Post-Quantum Auth over IKEv2 – IPsec Series, Part 8](https://daily.dev/posts/mutual-post-quantum-auth-over-ikev2-ipsec-series-part-8-xm1etcoxb) · Cisco · 1 upvotes · 0 comments - [ML-KEM vs Diffie-Hellman: The Showdown – IPsec Series, Part 3](https://daily.dev/posts/ml-kem-vs-diffie-hellman-the-showdown-ipsec-series-part-3-hyqdbip5i) · Cisco · 0 upvotes · 0 comments - [A Different Road to Quantum Safety: The PPK – IPsec Series, Part 5](https://daily.dev/posts/a-different-road-to-quantum-safety-the-ppk-ipsec-series-part-5-wubysbvmg) · Cisco · 0 upvotes · 0 comments - [The Great Certificate Size Explosion – IPsec Series, Part 7](https://daily.dev/posts/the-great-certificate-size-explosion-ipsec-series-part-7-qqoeuqaeo) · Cisco · 1 upvotes · 0 comments --- Tags: [#docker](https://daily.dev/tags/docker), [#quantum-computing](https://daily.dev/tags/quantum-computing) [View this post on daily.dev](https://daily.dev/posts/watch-a-hybrid-post-quantum-handshake-on-the-wire-ipsec-series-part-4-rpovq4vpj) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Watch a Hybrid Post-Quantum Handshake on the Wire – IPsec Series, Part 4","url":"https://daily.dev/posts/watch-a-hybrid-post-quantum-handshake-on-the-wire-ipsec-series-part-4-rpovq4vpj","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/watch-a-hybrid-post-quantum-handshake-on-the-wire-ipsec-series-part-4-rpovq4vpj"},"datePublished":"2026-07-27T14:02:38.721Z","dateModified":"2026-07-27T14:03:05.213Z","description":"A hands-on lab that builds a hybrid post-quantum IKEv2 VPN tunnel using two Docker containers running strongSwan. 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