[strongSwan] Strongswan Host-to-Host Connection Linux to Windows

[G J]

Here’s what I use for my system. Both Win10 and Win11 are able to connect to it just fine. I’m using certs rather than psk, but you should be able to work past that. Also, you might want to have a look at https://github.com/gitbls/pistrong/blob/master/CertInstall.md. Although it discusses installing Certs on Win10, some of the settings are appropriate regardless whether it’s cert or psk.

    windows-pubkey-ikev2 {
        version = 2
        proposals = aes256-sha1-modp1024,aes192-sha256-modp3072,default
        rekey_time = 0s
        pools = primary-pool-ipv4
        fragmentation = yes
        dpd_delay = 30s

        local-1 {
             auth = pubkey
             cacerts = strongSwanCACert.pem
             certs = windows-strongSwanVPNCert.pem
             id = windows.mydom.com
        }

        remote-1 {
             id = %any
        }

        children {
             net-windows {
                 local_ts = 0.0.0.0/0
                 rekey_time = 0s
                 dpd_action = clear
                 esp_proposals = aes256-sha1-modp1024,aes192-sha256-modp3072,default
             }
        }
    }
}
    pools {
    primary-pool-ipv4 {
        addrs = 10.92.10.0/24
        dns = 192.168.92.3
    }
}


From: Users <users-bounces at lists.strongswan.org> On Behalf Of Tyler Phillippe
Sent: Friday, May 20, 2022 6:51 AM
To: IL Ka <kazakevichilya at gmail.com>
Cc: users at lists.strongswan.org
Subject: Re: [strongSwan] Strongswan Host-to-Host Connection Linux to Windows

Here are the Linux logs - connecting to a Win10 21H2 machine right now for testing, will migrate over to Server 2019/2022 eventually. Thanks!

09[NET] received packet: from Windows[500] to Linux[500] (256 bytes)
09[ENC] parsed ID_PROT request 0 [ SA V V V V V V V V ]
09[IKE] no IKE config found for Linux...Windows, sending NO_PROPOSAL_CHOSEN
09[ENC] generating INFORMATIONAL_V1 request 2032397121 [ N(NO_PROP) ]
09[NET] sending packet: from Linux[500] to Windows[500] (40 bytes)
05[NET] received packet: from Windows[500] to Linux[500] (256 bytes)
05[ENC] parsed ID_PROT request 0 [ SA V V V V V V V V ]
05[IKE] no IKE config found for Linux...Windows, sending NO_PROPOSAL_CHOSEN
05[ENC] generating INFORMATIONAL_V1 request 1617066194 [ N(NO_PROP) ]
05[NET] sending packet: from Linux[500] to Windows[500] (40 bytes)
11[NET] received packet: from Windows[500] to Linux[500] (256 bytes)
11[ENC] parsed ID_PROT request 0 [ SA V V V V V V V V ]
11[IKE] no IKE config found for Linux...Windows, sending NO_PROPOSAL_CHOSEN
11[ENC] generating INFORMATIONAL_V1 request 728440835 [ N(NO_PROP) ]
11[NET] sending packet: from Linux[500] to Windows[500] (40 bytes)

On Fri, May 20, 2022 at 9:43 AM IL Ka <kazakevichilya at gmail.com<mailto:kazakevichilya at gmail.com>> wrote:
What about Linux logs?
Run ``swanctl --log`` on Linux and reinitiate connection.
Which version of Windows btw?

On Fri, May 20, 2022 at 4:16 PM Tyler Phillippe <tylerphillippe at gmail.com<mailto:tylerphillippe at gmail.com>> wrote:
Hello all! I am attempting to connect a Linux machine to Windows via Strongswan in a host-to-host configuration. I tested with Windows to Windows using the built-in firewall and it connected instantly. I changed the default Windows integrity and encryption ciphers and I think I changed them in the Linux Strongswan configuration. However, I am not getting any connection between the hosts and I can't find any logs on the Windows machine to help me narrow down what the issue is. It definitely does not work, since the SSH session on the Linux machine fails out. Below is the swanctl.conf file on my Linux machine. And, I know it's not the most secure method - I'm just trying to get it to initially connect with a PSK since that's the simplest for now. Windows doesn't support modp3072 unfortunately, so I had to manually set the Linux config below to modp2048. The Windows firewall is set to use AES-CBC 128, SHA-256, MODP2048 for key exchange and ESP AES-CBC 128, SHA-256 for data protection. What am I doing wrong? Thanks everyone!!

connections {
    linuxHost {
        local_addrs =  (Linux machine)
        remote_addrs =  (Windows machine)
        proposals = aes128-sha256-modp2048
        local {
            auth = psk
        }
        remote {
            auth = psk
        }
        children {
            linuxHost {
                esp_proposals = aes128-sha256-modp2048
                mode = transport
            }
        }
        version = 2
        reauth_time = 10800
    }
}

secrets {
    ike {
        secret = <psk>
    }
}
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