[strongSwan] swanctl -l - loses transport info?

[Kostya Vasilyev]

On Thu, Apr 4, 2019, at 9:42 PM, Noel Kuntze wrote:
> Hi,
> 
> In IKEv2, the KEX in P2 is only displayed when it actually occurs. In 
> any case, in the first CHILD_SA of a new IKE_SA, there's no KEX when it 
> is negotiated, so it's not displayed, because the KEX algorithm and 
> keylength are unknown. When a new CHILD_SA is negotiated (which 
> rekeying uses), a KEX is made, thus the algorithm and keylengtha re 
> known and it is displayed. You can easily recreate that scenario with 
> `swanctl --rekey [...]`.

Thank you. Exactly what I just discovered too :)

So I guess another way to look at this is - 

- the initial SA doesn't need to do a key exchange because it was just done by IKE

- rekeying does, and uses that configured ECP256 (or DH groups etc.)

Correct (more or less)?

-- K

> 
> Kind regards
> 
> Noel
> 
> Am 04.04.19 um 20:32 schrieb Kostya Vasilyev:
> > Hi,
> > 
> > I'm seeing something weird with the output of "swanctl -l".
> > 
> > Sometimes the SA's are output like this:
> > 
> > home_gre: #3, reqid 3, INSTALLED, TRANSPORT, ESP:AES_CTR-128/HMAC_SHA2_256_128
> > 
> > linode: #4, reqid 4, INSTALLED, TRANSPORT, ESP:AES_GCM_16-128
> > 
> > And sometimes like this:
> > 
> > home_gre: #6, reqid 6, INSTALLED, TRANSPORT, ESP:AES_CTR-128/HMAC_SHA2_256_128/ECP_256
> > 
> > linode: #4, reqid 4, INSTALLED, TRANSPORT, ESP:AES_GCM_16-128/ECP_256
> > 
> > The variation is in the "/ECP256" at the end.
> > 
> > I think this varies depending on how I start strongSwan (swanctl -q vs. systemctl restart) or maybe rekeying.
> > 
> > But my server and client configs don't change.
> > 
> > My server config is like this:
> > 
> > connections {
> > 	ec_tunnel {
> > 		version = 2
> > 		proposals = aes128-sha256-ecp256
> > 
> > 		// local, remote adds and auth omitted
> > 		
> > 		children {
> > 			home_gre {
> > 				local_ts  = dynamic[gre]
> > 				remote_ts = dynamic[gre]
> > 
> > 				mode = transport
> > 				esp_proposals = aes128ctr-sha256-ecp256
> > 			}
> > 
> > 			linode {
> > 				mode = transport
> > 				esp_proposals = aes128gcm128-ecp256
> > 			}
> > 		}
> > 	}
> > }
> > 
> > Client config for "linode" clinets:
> > 
> > connections {
> > 	ecdsa_tunnel {
> > 		version = 2
> > 		proposals = aes128-sha256-ecp256
> > 
> > 		// local, remote adds and auth omitted
> > 		
> > 		children {
> > 			fra  {
> > 				mode = transport
> > 				esp_proposals = aes128gcm128-ecp256
> > 				start_action = start
> > 				close_action = start
> > 				dpd_action = restart
> > 			}
> > 		}
> > 	}
> > }
> > 
> > Client "home_gre" (AES CTR) is a Miktotik at home and it also has ECP256 in its SA encryption config.
> > 
> > Does this look like a bug in swanctl -l ?
> > 
> > Or - most likely - user error?
> > 
> > I got ideas for my crypto settings from here:
> > 
> > https://wiki.strongswan.org/projects/strongswan/wiki/IKEv2CipherSuites
> > 
> > Suite-B-GCM-128:
> > IKEv2: aes128gcm16-prfsha256-ecp256
> > ESP: aes128gcm16-ecp256
> > 
> > Except I can't use GCM or PRF for IKE because of the Mikrotik client.
> > 
> 
> 
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