Examples

! deny ftp data (this is a comment)
access-list 101 deny tcp 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255 eq 20

access-list 101 –> this is the specific access list
deny –> disallow access
tcp –> protocol to deny
0.0.0.0 255.255.255.255 –> any
0.0.0.0 255.255.255.255 –> any
eq –> equal to
20 –> port 20 the ftp data port
Each of the examples follows a similar flow.

! deny ftp commands
acc 101 deny tcp 0.0.0.0 255.255.255.255 0.0.0.0 255.255.255.255 eq 21

! sshd to sshd servers only
acc 101 permit tcp 0.0.0.0 255.255.255.255 your.sshd.ser.ver 0.0.0.0 eq 22