Add support for config file

dropbear_hook

@@ -4,8 +4,15 @@ run_hook() {
     [ -d /dev/pts ] || mkdir -p /dev/pts
     mount -t devpts devpts /dev/pts
 
-    echo "Starting dropbear"
-    /usr/sbin/dropbear -E -s -j -k
+    if [ -s /etc/dropbear/config ]; then
+        echo "Found dropbear config file"
+        . /etc/dropbear/config
+    fi
+
+    port=${DROPBEAR_PORT:-22}
+
+    echo "Starting dropbear on port $port"
+    /usr/sbin/dropbear -E -s -j -k -p "$port"
 }
 
 run_cleanuphook() {