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Forum Replies

  1. johxxn says:

    Hi Rene,

    I have that too, R2 points to the ASA, but the lab did not work for me. I think it is a static NAT issue because the ASA drops the packet due to rpf-check. Here is a packet tracer from the ASA

    ciscoasa# packet-tracer input OUTSIDE tcp 23 23
    Phase: 1
    Result: ALLOW
    Implicit Rule
    Additional Information:
    MAC Access list
    Phase: 2
    Subtype: input
    Result: ALLOW
    Additional Information:
    in   DMZ
    Phase: 3
    Subtype: log
    Result: ALLOW
    access-group OUTSIDE_INBOUND in interface OUTSIDE
    access-list OUTSIDE_INBOUND extended permit tcp any host eq telnet 
    Additional Information:
    Phase: 4
    Type: IP-OPTIONS
    Result: ALLOW
    Additional Information:
    Phase: 5
    Type: NAT
    Subtype: rpf-check
    Result: DROP
    object network WEB_SERVER
     nat (DMZ,OUTSIDE) static
    Additional Information:
    input-interface: OUTSIDE
    input-status: up
    input-line-status: up
    output-interface: DMZ
    output-status: up
    output-line-status: up
    Action: drop
    Drop-reason: (acl-drop) Flow is denied by configured rule
  2. Hi Rene,

    Awesome lab.

    Quick question I come from cisco IOS routing and switching background and had a question about the ACL Processing, how does it process the ACLs in terms of do i need to enter a permit ip any any at the end of each ACL Name?


  3. Hi Rene,

    a question regarding those statements:

    •When you create an ACL statement for inbound traffic (lower to higher security level) then the destination IP address has to be: ◦The translated address for any ASA version before 8.3.
    ◦The real address for ASA 8.3 and newer.

    •The access-list is always checked before NAT translation.

    If the ACL is checked first, does the dest IP not have to be the NAT´d IP then?
    Cause the ASA looks at the packet and compares it to the ACL. In the packet we still have the NAT´d IP and therefore we would need to specify the NAT´d IP in the ACL, or not?
    Cause otherwise the ACL wouldn’t match the packet!?


  4. Thanks a lot for your help Laz!!

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