[master] Use alias/-alias for ifconfig calls in netbsd & openbsd client scripts

    Merges rt31573.

RELNOTES

@@ -1124,6 +1124,11 @@ by Eric Young (eay@cryptsoft.com).
   number of false positives when UDP checksum offloading is enabled.
   [ISC-bugs #41757]
 
+- Replaced ifconfig parameters "add" and "delete" with "alias" and "-alias"
+  for IPv6 mode in the client scripts, netbsd and openbsd.  This was
+  preventing IPv6 addresses from being added or removed from interfaces.
+  [ISC-bugs #31573]
+
 			Changes since 4.2.0 (new features)
 
 - If a client renews before 'dhcp-cache-threshold' percent of its lease

client/scripts/netbsd

@@ -314,7 +314,7 @@ if [ ${reason} = BOUND6 ] ; then
     exit_with_hooks 2;
   fi
 
-  ifconfig ${interface} inet6 add ${new_ip6_address}/${new_ip6_prefixlen}
+  ifconfig ${interface} inet6 alias ${new_ip6_address}/${new_ip6_prefixlen}
 
   # Check for nameserver options.
   make_resolv_conf
@@ -351,7 +351,7 @@ if [ ${reason} = EXPIRE6 -o ${reason} = RELEASE6 -o ${reason} = STOP6 ] ; then
     exit_with_hooks 2;
   fi
 
-  ifconfig ${interface} inet6 delete ${old_ip6_address}/${old_ip6_prefixlen}
+  ifconfig ${interface} inet6 -alias ${old_ip6_address}/${old_ip6_prefixlen}
 
   exit_with_hooks 0
 fi

client/scripts/openbsd

@@ -308,7 +308,7 @@ if [ ${reason} = BOUND6 ] ; then
     exit_with_hooks 2;
   fi
 
-  ifconfig ${interface} inet6 add ${new_ip6_address}/${new_ip6_prefixlen}
+  ifconfig ${interface} inet6 alias ${new_ip6_address}/${new_ip6_prefixlen}
 
   # Check for nameserver options.
   make_resolv_conf
@@ -345,7 +345,7 @@ if [ ${reason} = EXPIRE6 -o ${reason} = RELEASE6 -o ${reason} = STOP6 ] ; then
     exit_with_hooks 2;
   fi
 
-  ifconfig ${interface} inet6 delete ${old_ip6_address}/${old_ip6_prefixlen}
+  ifconfig ${interface} inet6 -alias ${old_ip6_address}/${old_ip6_prefixlen}
 
   exit_with_hooks 0
 fi