Improve VPN config

- Clean up obsolete Libreswan keywords

extras/ikev2setup.sh

@@ -169,7 +169,7 @@ confirm_or_abort() {
 show_header() {
 cat <<'EOF'
 
-IKEv2 Script   Copyright (c) 2020-2025 Lin Song   1 Sep 2025
+IKEv2 Script   Copyright (c) 2020-2025 Lin Song   2 Sep 2025
 
 EOF
 }
@@ -1197,7 +1197,6 @@ conn ikev2-cp
   narrowing=yes
   dpddelay=30
   retransmit-timeout=300s
-  dpdaction=clear
   auto=add
   ikev2=insist
   rekey=no

vpnsetup_alpine.sh

@@ -353,10 +353,8 @@ conn shared
   authby=secret
   pfs=no
   rekey=no
-  keyingtries=5
   dpddelay=30
   dpdtimeout=300
-  dpdaction=clear
   ikev2=never
   ike=aes256-sha2;modp2048,aes128-sha2;modp2048,aes256-sha1;modp2048,aes128-sha1;modp2048
   phase2alg=aes_gcm-null,aes128-sha1,aes256-sha1,aes256-sha2_512,aes128-sha2,aes256-sha2

vpnsetup_amzn.sh

@@ -377,10 +377,8 @@ conn shared
   authby=secret
   pfs=no
   rekey=no
-  keyingtries=5
   dpddelay=30
   dpdtimeout=300
-  dpdaction=clear
   ikev2=never
   ike=aes256-sha2;modp2048,aes128-sha2;modp2048,aes256-sha1;modp2048,aes128-sha1;modp2048
   phase2alg=aes_gcm-null,aes128-sha1,aes256-sha1,aes256-sha2_512,aes128-sha2,aes256-sha2

vpnsetup_centos.sh

@@ -484,10 +484,8 @@ conn shared
   authby=secret
   pfs=no
   rekey=no
-  keyingtries=5
   dpddelay=30
   dpdtimeout=300
-  dpdaction=clear
   ikev2=never
   ike=aes256-sha2;modp2048,aes128-sha2;modp2048,aes256-sha1;modp2048,aes128-sha1;modp2048
   phase2alg=aes_gcm-null,aes128-sha1,aes256-sha1,aes256-sha2_512,aes128-sha2,aes256-sha2

vpnsetup_ubuntu.sh

@@ -441,10 +441,8 @@ conn shared
   authby=secret
   pfs=no
   rekey=no
-  keyingtries=5
   dpddelay=30
   dpdtimeout=300
-  dpdaction=clear
   ikev2=never
   ike=aes256-sha2;modp2048,aes128-sha2;modp2048,aes256-sha1;modp2048,aes128-sha1;modp2048
   phase2alg=aes_gcm-null,aes128-sha1,aes256-sha1,aes256-sha2_512,aes128-sha2,aes256-sha2