[c-nsp] ACL to block udp/0?

Hank Nussbacher via cisco-nsp <[email protected]> Tue, 5 Dec 2023 23:27:21 +0200

Newsgroups	gmane.network.nsp.cisco
Message-ID	<[email protected]>

We encountered something strange.  We run IOS-XR 7.5.2 on ASR9K platform.

Had a user under udp/0 attack.  Tried to block it via standard ACL:


ipv4 access-list block-zero
  20 deny udp any any eq 0
  30 deny tcp any any eq 0
  40 permit ipv4 any any


Applied to interface:

  ipv4 access-group block-zero ingress
  ipv4 access-group block-zero egress


Yet, based on Kentik, we had no effect and the udp/0 attack just 
continued - as if the Cisco ACL is totally ignored.  Or am I missing 
something in the ACL listed above?


Thanks,

Hank

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