Libreswan Documentation

Logo

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

It’s assumed that the test basic-pluto-01 is is causing problems on east.

First, check that Makefile.inc.local does not contain KVM_RUN_POST_MORTEM=true. If it does, ./kvm will shutdown pluto and destroy the VMs.

Core Dump During A Test

Run the test, then login and use GDB to examine the core dump:

./kvm install # only when a re-build is needed
./kvm check testing/pluto/basic-pluto-01`
./kvm sh east
east# gdb --core /tmp/core.pluto.NNN
(gdb) bt
(gdb) list
(gdb) up
(gdb) up
(gdb) list
(gdb) print variable

Core Dump During Shutdown

Run the test, then login and attach to the running pluto process using GDB. Then, from the debugger, run the shutdown command in the background:

./kvm install # only when a re-build is needed
./kvm check testing/pluto/basic-pluto-01`
./kvm sh east
east# gdb --args /usr/local/libexec/ipsec/pluto $(pidof pluto)
(gdb) shell ipsec shutdown &   # run command in background
(gdb) continue                 # let pluto process request
... crash happens ...
(gdb) bt

Note the &. This causes ipsec shutdown to be run in the background.

Disabling systemd’s watchdog timer

For more longer debugging sessions, where pluto may be paused while you’re pokeing around with the debugger, systemd’s watchdog timer will need to be. Otherwise it will fire, killing pluto.

Temporarily disable systemd’s watchdog timer

First boot the test domains used by the test basic-pluto-01

./kvm boot testing/pluto/basic-pluto-01

Next modify ipsec.service so that the watchdog timer is disabled:

./kvm sh east
east# sed -i -e '/WatchdogSec=/ s/^/#/' /usr/lib/systemd/system/ipsec.service

Now the tests can be run manually using east and west’s consoles:

east# cd /testing/basic-pluto-01
east# ./eastinit.sh
east# gdb --args /usr/local/libexec/ipsec/pluto $(pidof pluto)
(gdb) continue
....
./kvm sh west
east# cd /testing/basic-pluto-01
east# ./westinit.sh
east# ./westrun.sh

Note: because the test domains are transient, shutting down and then booting will loose this change.

Permanently disable systemd’s watchdog timer

systemd’s watchdog timer can be permanently disabled in the KVM build by adding KVM_USE_SYSTEMD_WATCHDOG=false to Makefile.inc.local.

Interactively Debugging A Test

This time both east and west are used. And pluto is started manually (not via systemd). Two terminals are required.

In the first terminal get pluto started on east with connection loaded. Notice how ipsec add connection is invoked by momentarily halting pluto, running the command in the background, and then continuing pluto:

./kvm install # only when a re-build is needed
./kvm sh east
east# /testing/guestbin/swan-prep ...
east# gdb --args /usr/local/libexec/ipsec/pluto --nofork --config /etc/ipsec.conf --stderrlog  --log-no-time
(gdb) run
^C
(gdb) shell ipsec add connection &
(gdb) continue

Next, in the second terminal, start pluto on west, load and then initiate connection:

./kvm sh west
west# /testing/guestbin/swan-prep ...
west# gdb --args /usr/local/libexec/ipsec/pluto --nofork --config /etc/ipsec.conf --stderrlog  --log-no-time
(gdb) run
^C
(gdb) shell ipsec add connection &
(gdb) continue
^C
(gdb) shell ipsec up connection &
(gdb) continue
...crash...

Finally

Once things seem to be fixed, be sure to run the test from scratch, including post-mortem:

./kvm install check -pm testing/pluto/basic-pluto-01