StrongSwan – Multiple Roadwarrior Connections on Different Subnets

ipsecpoint-to-site-vpnstrongswanvpnwindows

I'm trying to setup a StrongSwan VPN Server which should host multiple (Windows 10 – internal vpn client) roadwarrior connections, but different subnets, depending on the clients certificate.

root@VPN:/# ipsec version

Linux strongSwan U5.8.2/K5.4.0-26-generic

My setup has 2 pairs of public and private key, using a different CNs let's say vpn-dev.mycom.com and vpn-liv.mycom.com. The used ipsec.conf looks something like this:

conn vpn-dev
    auto=add
    compress=no
    type=tunnel
    keyexchange=ikev2
    fragmentation=yes
    forceencaps=yes
    dpdaction=clear
    dpddelay=300s
    rekey=no
    ikelifetime=25200s
    leftid=vpn-dev.mycom.com
    leftcert=server-cert.pem
    leftsendcert=always
    leftsubnet=0.0.0.0/0
    right=%any
    rightid=%any
    rightauth=eap-mschapv2
    rightsourceip=10.100.0.0/16-10.100.254.254/16
    rightdns=8.8.8.8,8.8.4.4
    rightsendcert=never
    rightcert=ca-cert.pem
    eap_identity=%identity
    ike=aes128-sha1-modp1024


conn vpn-liv
    also=vpn-dev
    leftid=vpn-liv.mycom.com
    leftcert=liv-server-cert.pem
    rightsourceip=10.200.0.0/16-10.200.254.254/16
    rightcert=liv-ca-cert.pem

both certificate keys are also stored in the ipsec.secrets

vpn-dev.mycom.com : RSA "server-key.pem"
vpn-liv.mycom.com : RSA "liv-server-key.pem"

someuser : EAP "somepassword"

However as soon as i try to connect to the strongswan instance, the vpn-dev connection is used and strongswan is not switching to conn vpn-liv

here are the logs during a try:

Mar 30 08:47:48 VPN charon: 16[NET] received packet: from X.X.X.X[64558] to X.X.X.X[500] (1084 bytes)
Mar 30 08:47:48 VPN charon: 16[IKE] received MS NT5 ISAKMPOAKLEY v9 vendor ID
Mar 30 08:47:48 VPN charon: 16[IKE] received MS-Negotiation Discovery Capable vendor ID
Mar 30 08:47:48 VPN charon: 16[IKE] X.X.X.X is initiating an IKE_SA
Mar 30 08:47:48 VPN charon: 16[CFG] selected proposal: IKE:AES_CBC_128/HMAC_SHA1_96/PRF_HMAC_SHA1/MODP_1024
Mar 30 08:47:48 VPN charon: 16[IKE] local host is behind NAT, sending keep alives
Mar 30 08:47:48 VPN charon: 16[IKE] remote host is behind NAT
Mar 30 08:47:48 VPN charon: 16[NET] sending packet: from X.X.X.X[500] to X.X.X.X[64558] (328 bytes)
Mar 30 08:47:48 VPN charon: 06[NET] received packet: from X.X.X.X[64596] to X.X.X.X[4500] (576 bytes)
Mar 30 08:47:48 VPN charon: 10[NET] received packet: from X.X.X.X[64596] to X.X.X.X[4500] (576 bytes)
Mar 30 08:47:48 VPN charon: 05[NET] received packet: from X.X.X.X[64596] to X.X.X.X[4500] (576 bytes)
Mar 30 08:47:48 VPN charon: 14[NET] received packet: from X.X.X.X[64596] to X.X.X.X[4500] (368 bytes)
Mar 30 08:47:48 VPN charon: 14[IKE] received cert request for "CN=PRIV VPN LIV CA"
Mar 30 08:47:48 VPN charon: 14[IKE] received 69 cert requests for an unknown ca
Mar 30 08:47:48 VPN charon: 14[CFG] looking for peer configs matching X.X.X.X[%any]...X.X.X.X[192.168.0.117]

Mar 30 08:47:48 VPN charon: 14[CFG] selected peer config 'vpn-dev' # << here it has not selected vpn-live, even if the earlier provided private key is only matching vpn-live

Mar 30 08:47:48 VPN charon: 14[IKE] initiating EAP_IDENTITY method (id 0x00)
Mar 30 08:47:48 VPN charon: 14[IKE] peer supports MOBIKE
Mar 30 08:47:48 VPN charon: 14[IKE] authentication of 'vpn-dev.mycom.com' (myself) with RSA     signature successful
Mar 30 08:47:48 VPN charon: 14[IKE] sending end entity cert "CN=vpn-dev.mycom.com"
Mar 30 08:47:49 VPN charon: 14[IKE] sending cert request for "CN=PRIV VPN DEV CA"
Mar 30 08:47:49 VPN charon: 14[IKE] sending cert request for "CN=PRIV VPN LIV CA"
Mar 30 08:47:49 VPN charon: 14[NET] sending packet: from X.X.X.X[500] to X.X.X.X[64548] (364 bytes)
Mar 30 08:47:49 VPN charon: 06[NET] received packet: from X.X.X.X[64618] to X.X.X.X[4500] (92 bytes)
Mar 30 08:47:49 VPN charon: 06[IKE] received (28) error notify

the goal is basically to host 2 vpn endpoints on one machine but provide different ip ranges depending on the login / used certificate.

The local configuration is done with (powershell)

Import-Certificate -FilePath liv-ca-cert.pem -CertStoreLocation 'Cert:\LocalMachine\Root'
Add-VpnConnection -Name 'LIV VPN' -ServerAddress 'vpn-live.mycom.com' -AuthenticationMethod Eap -IdleDisconnectSeconds 43200

am i missing something?
is my setup misconfigured?
or is this simply not possible with strongswan and windows 10 internal vpn client?

Best Answer

It's only possible to switch connections based on the server identity/certificate if either

  • the clients send a remote identity (IDr) in their IKE_AUTH request, which many clients don't (in particular Windows), otherwise, there is no identity to match, so the first connection will be used

or

  • if the FQDNs map to different IP addresses, which can be configured as local addresses for the connections so the correct connection is selected early on
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