ovpn_run: Don't call sysctl which requires --privileged

* Instead encourage the user to change how they invoke docker.

Author: kylemanna

bin/ovpn_run

@@ -87,13 +87,18 @@ fi
 
 ip -6 route show default 2>/dev/null
 if [ $? = 0 ]; then
-    echo "Enabling IPv6 Forwarding"
-    # If this fails, ensure the docker container is run with --privileged
-    # Could be side stepped with `ip netns` madness to drop privileged flag
+    echo "Checking IPv6 Forwarding"
+    if [ "$(</proc/sys/net/ipv6/conf/all/disable_ipv6)" != "0" ]; then
+        echo "Sysctl error for disable_ipv6, please run docker with '--sysctl net.ipv6.conf.all.disable_ipv6=0'"
+    fi
+
+    if [ "$(</proc/sys/net/ipv6/conf/default/forwarding)" != "1" ]; then
+        echo "Sysctl error for default forwarding, please run docker with '--sysctl net.ipv6.conf.default.forwarding=1'"
+    fi
 
-    sysctl -w net.ipv6.conf.all.disable_ipv6=0 || echo "Failed to enable IPv6 support"
-    sysctl -w net.ipv6.conf.default.forwarding=1 || echo "Failed to enable IPv6 Forwarding default"
-    sysctl -w net.ipv6.conf.all.forwarding=1 || echo "Failed to enable IPv6 Forwarding"
+    if [ "$(</proc/sys/net/ipv6/conf/all/forwarding)" != "1" ]; then
+        echo "Sysctl error for all forwarding, please run docker with '--sysctl net.ipv6.conf.all.forwarding=1'"
+    fi
 fi
 
 echo "Running 'openvpn ${ARGS[@]} ${USER_ARGS[@]}'"