Merged in dev/vladimir/mpc-3028-network-quality-for-robots (pull requ…

…est elastic#261)

[MPC-3028] improvements to network quality control script

* a script to simulate UDP network losses

* if/while code style

* feedback from Can

* mention default value for loss level

* remove default identity

* limit udp ports

* improvements suggested by Serge

* merge conflict resolved

aws/gen-students-tf/simulate-losses.sh

@@ -11,22 +11,26 @@ SSH_IDENTITY=""
 function usage() {
     cat << EOF
 
-Usage: $0 [-t <target>] [-c <cmd>] [-l <loss>] [-I <identity>]
+Usage: $0 [-H <target>] [-c <cmd>] [-l <loss>] [-I <identity>]
 
     arguments
     ---
-    -t: target, username@hostname
+    -H: target, username@hostname
     -c: command to execute
     -l: specify loss from 0.00 to 0.50, defaults to 0.10
     -I: path to your identity file if needed
 
     commands
     ---
     * list — list all the applied rules
-    * add — add a specific loss rule
-    * remove — remove a specific loss rule
+    * add — add a rule with a specified loss
+    * remove — remove a rule with a specified loss
     * reset — scan for all the related rules and remove them
 
+    example
+    ---
+    ./simulate-losses.sh -I ~/.ssh/Engageli-Stockholm.pem -H ubuntu@13.51.158.18 -c add -l 0.12
+
 EOF
 }
 
@@ -35,9 +39,9 @@ if [ $# -eq 0 ] ; then
   exit 1
 fi
 
-while getopts "I:c:l:t:" opt; do
+while getopts "H:I:c:l:" opt; do
     case $opt in
-        t)
+        H)
             TARGET=$OPTARG
             ;;
         c)