diff --git a/doc/tutorials/using_ubuntu_as_sos.rst b/doc/tutorials/using_ubuntu_as_sos.rst
index ead2b1512..4d1e92b86 100644
--- a/doc/tutorials/using_ubuntu_as_sos.rst
+++ b/doc/tutorials/using_ubuntu_as_sos.rst
@@ -355,15 +355,15 @@ script example shows how to set this up (verified in Ubuntu 16.04 and 18.04 as t
      
      # if bridge not existed
      if [ "$br"x != "acrn-br0"x ]; then
-	     # setup bridge for uos network
+	    # setup bridge for uos network
      	brctl addbr acrn-br0
-	     brctl addif acrn-br0 enp3s0
-	     ifconfig enp3s0 0
-	     dhclient acrn-br0
-	     # add existing tap devices under the bridge
-	     for tap in $taps; do
-	     	ip tuntap add dev acrn_$tap mode tap
-	     	brctl addif acrn-br0 $tap
+	    brctl addif acrn-br0 enp3s0
+	    ifconfig enp3s0 0
+	    dhclient acrn-br0
+	    # add existing tap devices under the bridge
+	    for tap in $taps; do
+			ip tuntap add dev acrn_$tap mode tap
+			brctl addif acrn-br0 $tap
 	     	ip link set dev $tap down
 	     	ip link set dev $tap up
 	     done