<div dir="ltr">Hi, <div><br></div><div>From the below link, we see that strong-swan currently does not support this standard.</div><div><a href="https://wiki.strongswan.org/projects/strongswan/wiki/IpsecStandards">https://wiki.strongswan.org/projects/strongswan/wiki/IpsecStandards</a>  <br></div><div><br></div><div>However in 5.5.2 strongswan release note we found that </div><div><ul style="padding-left:2em;margin-bottom:2em;color:rgb(51,51,51);font-size:medium"><li style="list-style:square;margin-bottom:0.6em">Support for handling <code>IKEV2_MESSAGE_ID_SYNC</code> notifies as responder (usually the original initiator of an IKE_SA) as defined in <a class="external" href="https://tools.ietf.org/html/rfc6311" style="color:rgb(0,0,255);text-decoration-line:none">RFC 6311</a> was added</li></ul></div><div>Is there any possibility to support IPSEC_REPLAY_COUNTER_SYNC in any future release of strongswan to provide complete support for RFC 6311..</div><div><br></div><div>Regards, </div><div>Nishit.</div></div>