netlink error: Protocol not supported (93)

[martenfredriksson]

Hi,

I'm running the strongx509/strongswam image on Windows Subsystem for Linux (WSL) (ubuntu 20.04). When configuring a connection using ESP with transport mode everything worked fine. IKE_SA and CHILD_SA were successfully created, and traffic were protected using ESP.

children {
   psk {
      remote_ts = 192.168.0.3/32
      local_ts = 192.168.0.2/32
      esp_proposals = aes128gcm16
      dpd_action = trap
      mode = transport
   }
}

However when I change from ESP to AH (i.e. replacing "esp_proposals = aes128gcm16" with "ah_proposals = sha256"), I get an error when trying to create the CHILD_SA.

9[ENC] parsed CREATE_CHILD_SA request 2 [ SA No TSi TSr ]
09[CFG] selected proposal: AH:HMAC_SHA2_256_128/NO_EXT_SEQ
09[KNL] received netlink error: Protocol not supported (93)
09[KNL] unable to add SAD entry with SPI c473461b (FAILED)
09[KNL] received netlink error: Protocol not supported (93)
09[KNL] unable to add SAD entry with SPI cd62469f (FAILED)
09[IKE] unable to install inbound and outbound IPsec SA (SAD) in kernel
09[IKE] failed to establish CHILD_SA, keeping IKE_SA
09[KNL] deleting policy 10.3.0.1/32 === 10.1.0.0/24 in failed, not found
09[KNL] deleting policy 10.3.0.1/32 === 10.1.0.0/24 fwd failed, not found
09[ENC] generating CREATE_CHILD_SA response 2 [ N(NO_PROP) ]

Any idea what the problem can be?

Thankful for help,
Mårten