Libreswan Documentation

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Libreswan's Online Documentation

View the Project on GitHub libreswan/libreswan.github.io

Support
FAQ Common Error Messages
History
Implemented Standards
Kernel Support
HOWTO Additional ipsec.conf documentation
AWS Mesh
brendans Road Warrior Setup at Home
Configuration examples
Confuse !?@: github wiki
Enterprise cloud encryption
Entropy matters
EoIP shared ethernet LAN using IPsec
High Availability Fallover VPN in AWS
Host to host VPN
Host to host VPN with PSK
Libreswan as client to a Cisco ASA or VPN3000 server
Microsoft Azure configuration
Migrate from IKEv1 DPD to IKEv2 LIVENESS
Opportunistic IPsec
Opportunistic IPsec using LetsEncrypt
Pluto and DNSSEC
Read status output
Route based VPN
SElinux and Labeled IPsec VPN
Subnet extrusion
Subnet to subnet using NAT
Subnet to subnet VPN
Subnet to subnet VPN with PSK
Unauthenticated Opportunistic IPsec
Using Apache to serve PKCS
Using NSS Hardware Tokens
Using NSS with libreswan
VPN server for remote clients using IKEv2
VPN server for remote clients using IKEv2 split VPN
GSoC 2027 Code Project Ideas DRAFT
Contributor Guidance DRAFT
Completed Projects 2026 RFC 9593 Announcing Supported Authentication Methods in IKEv2
2026 Improve the ACQUIRE to IKE policy lookup
2026 Add HOST TO HOST Support on BSD
2021 RFC 8420 Add EdDSA Signature Authentication Support to IKEv2
2020 Session Resumption
2020 IKEv2 Interop testing with OpenBSD
2020 IKE Intermediate Exchange
2019 Libreswan Opportunistic IPsec using LetsEncrypt
2018 RSA PSS Support in compliance with RFC 7427 and RFC 8247
2018 RFC 7427 Add ECDSA Signature Authentication Support to IKEv2
2018 RFC 5685 Redirect Mechanism
2018 Managing Interface
2017 TCP encapsulation of IKE and IPsec
2017 RFC 7427 Add Signature Authentication Support to IKEv2
2017 Postquantum Preshared Keys
Presentations
IRC
Hacking Documentation
Git, GitHub, and Pull Requests
Merging GitHub Pull Requests
Programming Conventions
Testing Docker
KVM 1. Setup The Host
2. Configure Testing
3. Compile Libreswan
4. Test Libreswan
5. Accessing The Console
6. Maintenance and Internals
Bisecting
Debugging Pluto
Logging In Using SSH
Performance
Running A Custom Kernel
Running A Single Test
Running In The Background
Setup a Web Server
Testing Old Branches
Updating Test Results
Namespace Magic
Namespaces
Topology
Internals 3.14 X509
Benchmarking and Performance testing
Cipher suites and algorithm support
Cloud OE ideas
Compiling with AddressSanitizer
Compliance of RFC 7427 Signature Authentication in IKEv2
Coverity
Cryptographic Acceleration
Developer links strongswan android
Discouraged or forbidden C functions
IKEv2 Child SA
IKEv2 CP and EAP support
Introduction
Libreswan xfrm kernel support
Logging cleanup
New OE
Pluto
Pluto packet processing
Proposed ipsec ca command
Retransmit timings
Road Map
SAref code
Setting up system for debug logging
stf status
Testing 2017 Next Generation
Unbound
Uncrustify
Use Cases and Requirements document for ECC ECDSA support
Use Cases and Requirements document
XFRM Interface Development Notes
XFRM pCPU
XFRM pCPU RSS
Security Crypto boundary and certification
Libreswan and Heartbleed
Libreswan and TunnelCrack
Reporting a Vulnerability
Vulnerabilities
Meetups 2013 Helsinki
2014 San Francisco
2014 Toronto
2018 Toronto
Obsolete HOWTOs IKEv1 XAUTH with FreeOTP and FreeIPA
IKEv1 XAUTH with Google Authenticator One Time Passwords
Route based VPN using VTI
Testing Namespace
VPN server for remote clients using IKEv1 with L2TP
VPN server for remote clients using IKEv1 XAUTH with Certificates
VPN server for remote clients using IKEv1 XAUTH with PSK

Here’s a brief list showing which kernel features are supported.

Since the feature may require modifications to both the kernel and Libreswan, the version field can contain the following:

Blank just means no one has tested this.

RFC Feature Linux FreeBSD NetBSD OpenBSD Comments
             
  ipsec interface k4.19
2018		 k11.1
2017		 k8.0
2018		 k7.4
2023		  
  ipsec-interface w/ IPv4+IPv6 through single SA Yes Yes No Yes  
  All combinations of IPv4, IPv6, IPCOMP, TRANSPORT, TUNNEL k6.3?   10.0    
  Kernel NAT keepalive Yes
v?.?		       Libreswan needs changes
  Hardware Offload (i.e., ConnectX-7) Yes 15.1
2026		 No    
  Host-Host Yes v5.4 v5.4 v5.4 Remember vN.M is the Libreswan version
             
  Kernel Algorithms          
  AES_GCM Yes Yes Yes Yes  
  CHACHA Yes Yes No Yes  
draft Use of SHA-3 in the Internet Key Exchange Protocol Version 2 (IKEv2) and IPsec         It’s comming
             
  Sequence Numbers and Sliding Windows          
  ESP without sliding window         w/ Hardware it can be cheaper to decrypt packets
RFC 4302 Appendix B: Extended (64-bit) Sequence Numbers (AH) Yes Yes No Yes  
RFC 4303 Appendix A: Extended (64-bit) Sequence Numbers (ESP) Yes Yes No Yes  
RFC 6479 IPsec Anti-Replay Algorithm without Bit Shifting         Interesting Idea
  Large Sliding Window Yes Yes No    
             
RFC 3948 UDP Encapsulation of IPsec ESP Packets Yes Yes Yes Yes  
RFC 4302 IP Authentication Header (AH) Yes Yes Yes Yes  
RFC 4303 IP Encapsulating Security Payload (ESP) Yes Yes Yes Yes  
             
RFC 9329 TCP Encapsulation of Internet Key Exchange Protocol (IKE) and IPsec Packets k5.1   No    
draft Separate Transports for IKE and ESP         Motivated by PQ
             
RFC 9347 Aggregation and Fragmentation Mode for Encapsulating Security Payload (ESP) and Its Use for IP Traffic Flow Security (IP-TFS) k6.14        
RFC 9478 Labeled IPsec Traffic Selector Support for the Internet Key Exchange Protocol Version 2 (IKEv2) Yes       Does anyone care?
draft Enhanced Encapsulating Security Payload (EESP)