An ACL is applied inbound on a router interface. The ACL consists of a single entry:
access-list 210 permit tcp 172.18.20.0 0.0.0.31 172.18.20.32 0.0.0.31 eq ftp .
If a packet with a source address of 172.18.20.14, a destination address of 172.18.20.40, and a protocol of 21 is received on the interface, is the packet permitted or denied?
- permitted
Explanation:
Source Address Match: The source wildcard mask of 0.0.0.31 combined with the network 172.18.20.0 defines a range from 172.18.20.0 to 172.18.20.31. The packet's source address, 172.18.20.14, falls within this permitted range.
Destination Address Match: The destination wildcard mask of 0.0.0.31 combined with 172.18.20.32 defines a range from 172.18.20.32 to 172.18.20.63. The packet's destination address, 172.18.20.40, falls within this permitted range.
Protocol and Port Match: The ACL specifies TCP and the operator eq ftp (port 21). The packet uses protocol 21 (FTP), satisfying the final criteria. Since all conditions (source, destination, protocol, and port) match the permit statement, the packet is allowed.
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