only match beginning of the chain names in the regex

docker-prestart-iptables-flush.sh

@@ -9,7 +9,7 @@
 #
 for TABLE in nat mangle raw; do
 	iptables -v -t $TABLE -F
-	CHAINS=$(iptables -t $TABLE -L | egrep '^Chain' | awk '{print $2}' | egrep --color=never '(KUBE|DOCKER|cali)($|\-)')
+	CHAINS=$(iptables -t $TABLE -L | egrep '^Chain' | awk '{print $2}' | egrep --color=never '^(KUBE|DOCKER|cali)($|\-)')
 	for C in $CHAINS; do iptables -v -t $TABLE -X $C; done
 done
 
@@ -18,7 +18,7 @@ iptables -v -F FORWARD
 
 # Then go through the others deleting them after removing anything 
 # that refers to them
-DELETE_CHAINS=$(iptables -L | egrep '^Chain' | awk '{print $2}' | egrep --color=never '(KUBE|DOCKER|cali)($|\-)')
+DELETE_CHAINS=$(iptables -L | egrep '^Chain' | awk '{print $2}' | egrep --color=never '^(KUBE|DOCKER|cali)($|\-)')
 for DC in $DELETE_CHAINS; do
 	CHAINS=$(iptables -L | egrep '^Chain' | awk '{print $2}')
 	iptables -v -F $DC