<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Hello,<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have an iOS configuration profile that is proposing make the Phase 1 connection with Diffie-Hellman Group 21 (ecp521).<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have opened the profile in an XML editor and confirmed that the settings show DH Group 21:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><key>IKESecurityAssociationParameters</key><o:p></o:p></p><p class=MsoNormal><dict><o:p></o:p></p><p class=MsoNormal><key>DiffieHellmanGroup</key><o:p></o:p></p><p class=MsoNormal> <integer>21</integer><o:p></o:p></p><p class=MsoNormal> <key>EncryptionAlgorithm</key><o:p></o:p></p><p class=MsoNormal> <string>AES-256</string><o:p></o:p></p><p class=MsoNormal> <key>IntegrityAlgorithm</key><o:p></o:p></p><p class=MsoNormal> <string>SHA2-256</string><o:p></o:p></p><p class=MsoNormal> <key>LifeTimeInMinutes</key><o:p></o:p></p><p class=MsoNormal> <integer>1440</integer><o:p></o:p></p><p class=MsoNormal></dict><o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The same settings are reflected in my ipsec.conf file:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>conn GPIT<o:p></o:p></p><p class=MsoNormal> keyexchange=ike<o:p></o:p></p><p class=MsoNormal> ike=aes256-sha256-ecp521!<o:p></o:p></p><p class=MsoNormal> esp=aes256-sha256-ecp521!<o:p></o:p></p><p class=MsoNormal> dpdaction=clear<o:p></o:p></p><p class=MsoNormal> dpddelay=300s<o:p></o:p></p><p class=MsoNormal> rekey=no<o:p></o:p></p><p class=MsoNormal> left=%any<o:p></o:p></p><p class=MsoNormal> leftsubnet=0.0.0.0/0<o:p></o:p></p><p class=MsoNormal> leftcert=vpn03generalpurposeitcom.pem<o:p></o:p></p><p class=MsoNormal> leftfirewall=yes<o:p></o:p></p><p class=MsoNormal> leftid=vpn03.generalpurposeit.com<o:p></o:p></p><p class=MsoNormal> leftauth=pubkey<o:p></o:p></p><p class=MsoNormal> leftsendcert=always<o:p></o:p></p><p class=MsoNormal> right=%any<o:p></o:p></p><p class=MsoNormal> rightid=%any<o:p></o:p></p><p class=MsoNormal> rightauth=eap-radius<o:p></o:p></p><p class=MsoNormal> rightsendcert=never<o:p></o:p></p><p class=MsoNormal> rightsourceip=172.16.10.1/24<o:p></o:p></p><p class=MsoNormal> auto=add<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The log file shows the following:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Dec 19 13:41:15 vpn03 strongswan: 10[CFG] received proposals: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/MODP_1024<o:p></o:p></p><p class=MsoNormal>Dec 19 13:41:15 vpn03 strongswan: 10[CFG] configured proposals: IKE:AES_CBC_256/HMAC_SHA2_256_128/PRF_HMAC_SHA2_256/ECP_521<o:p></o:p></p><p class=MsoNormal>Dec 19 13:41:15 vpn03 strongswan: 10[IKE] received proposals unacceptable<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Without changing the configuration profile, if I change my ipsec.conf file to read “ike=aes256-sha256-modp1024!” it will connect…but since DH Group 2 is deprecated, I obviously cannot keep this long term. The Phase 2 connection works fine with the “esp=aes256-sha256-ecp521!” line in my ipsec.conf file.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I have read in the strongSwan wiki a reference to a known bug in iOS in iOS 9+ which reads “For manual configurations, specify only DH group 2 (modp1024) in the ike configuration. Although the iOS client claims to support modp1536, an unfixed bug prevents these connections from succeeding.” (<a href="https://wiki.strongswan.org/projects/strongswan/wiki/AppleClients">https://wiki.strongswan.org/projects/strongswan/wiki/AppleClients</a>) Is this still the case? I opened up a bug fix with Apple regarding this, but I haven’t seen any response yet. Thank you.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>R/s,<o:p></o:p></p><p class=MsoNormal>Brian<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>