[strongSwan] how to increase timeout for "deleting half open IKE_SA with <someIP> after timeout" ?

[Harald Dunkel]

Hi folks,

I have a few road warriors (3 out of ~140) having severe problems to
connect via IKEv2. Within the last 4 weeks they had >1000 problems
during IKE SA init each, e.g.:

May 12 09:55:28 18[NET1] <92244> received packet: from 192.168.1.177[61416] to 10.0.0.17[500] (432 bytes)
May 12 09:55:28 18[ENC1] <92244> parsed IKE_SA_INIT request 0 [ SA KE No N(REDIR_SUP) N(NATD_S_IP) N(NATD_D_IP) N(FRAG_SUP) ]
May 12 09:55:28 18[IKE0] <92244> 192.168.1.177 is initiating an IKE_SA
May 12 09:55:28 18[IKE2] <92244> IKE_SA (unnamed)[92244] state change: CREATED => CONNECTING
May 12 09:55:28 18[CFG1] <92244> selected proposal: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_2048
May 12 09:55:28 18[IKE1] <92244> remote host is behind NAT
May 12 09:55:28 18[IKE2] <92244> sending strongSwan vendor ID
May 12 09:55:28 18[IKE1] <92244> sending cert request for "C=DE, O=example AG, CN=ws-CA"
May 12 09:55:28 18[IKE1] <92244> sending cert request for "C=DE, O=example AG, OU=example Certificate Authority, CN=root-CA"
May 12 09:55:28 18[IKE1] <92244> sending cert request for "C=DE, ST=NRW, O=example AG, OU=TI, CN=ipsec-ca"
May 12 09:55:28 18[ENC1] <92244> generating IKE_SA_INIT response 0 [ SA KE No N(NATD_S_IP) N(NATD_D_IP) CERTREQ N(FRAG_SUP) N(CHDLESS_SUP) N(MULT_AUTH) V ]
May 12 09:55:28 18[NET1] <92244> sending packet: from 10.0.0.17[500] to 192.168.1.177[61416] (541 bytes)
May 12 09:55:58 31[JOB1] <92244> deleting half open IKE_SA with 192.168.1.177 after timeout
May 12 09:55:58 31[IKE2] <92244> IKE_SA (unnamed)[92244] state change: CONNECTING => DESTROYING

Obviously there is a 30sec timeout on the IPsec gateway. Is there
a chance to increase this timeout (using stroke, ie. ipsec.conf)?
https://wiki.strongswan.org/projects/strongswan/wiki/ConnSection
mentions only the DPD timeout (150 sec per default) and the inac-
tivity timeout (child sa only, as it seems).

Would it be wise to resend the IKE_SA_INIT response (lets say) 3
times?


Every helpful comment is highly appreciated

Harri