As per the concept of ASA, trafuc from inside (Sec 100) to DMZ ( Sec 50) is allowed by default. When I try write some acl (Host to Host block) on the Inside Interface, No other traffic is flowing to and from the Inside Interface.
Everything is blocked. Previously no ACL has been mapped to the Inside Interface.
Kindly help me to resolve this Issue and also provide the document for behaviour of Firewall before and after configuring the ACL.
You are right in terms of the default behave of the ASA as long as there is no ACL on the inside interface, however once there is an ACL this will filter any outgoing traffic. So, if you do not have ACL applied on the inside interface all the traffic will be permitted from a High (100) inteface to a low (50) interface BUT if there is an ACL this will filter ALL the traffic, whatever the values are.....The ACL you create for the inside inteface must permit all the outgoing traffic not only for the internet (outside interface) but also for the DMZ.
Post the acl you entered. Remember, there is an explicit deny any any at the end of the acl. So if you only want to prevent access to some dmz machine, then it has to be written properly. Allow what you want to allow to dmz, deny everything else to dmz, then allow everything else.