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Cisco Bug: CSCul68263 - tcp adjust-mss and ACL incorrect behavior in case of in2out NAT

Last Modified

Nov 27, 2020

Products (2)

  • Cisco 2600 Series Multiservice Platforms
  • Cisco 2600 Series Multiservice Platforms

Known Affected Releases

15.2(4)M4.3 15.3(3)S

Description (partial)

TCP/telnet is not working with NAT+ACL+TCP-adjust mss features.
Usage of egress "ip tcp adjust-mss" on output Tunnel seems changes the Features      
order of operation for TCP SYN packets.
NAT Inside-to-Outside gets performed on it first and only then ingress ACL, 
which are acting on already nat translated src_ipv4.

C7200 with
nat+acl on ingress interface:
ip tcp-adjast on egress interface
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