“My friend Mike Storm has come up with a good “base” ACL for use on Internet facing routers and firewall devices. While he has it listed on his blog, I am referencing it here for my own future reference.”

Assuming my PubNet range is a block of 32 66.238.29.0 – 31. See below

! no fragments
access-list 100 deny tcp any 66.238.29.0 0.0.0.31 log fragments
access-list 100 deny udp any 66.238.29.0 0.0.0.31 log fragments
access-list 100 deny icmp any 66.238.29.0 0.0.0.31 log fragments
! no snmp inbound from the Internet
access-list 100 deny udp any any eq snmp
access-list 100 deny udp any any eq snmptrap
! RFC 2827 Ingress, RFC 3804 Martian Filtering and RFC 1918 private Address Filtering
access-list 100 deny ip 127.0.0.0 0.255.255.255 any log
access-list 100 deny ip 255.0.0.0 0.255.255.255 any log
access-list 100 deny ip 224.0.0.0 31.255.255.255 any log
access-list 100 deny ip host 0.0.0.0 any log
access-list 100 deny ip 10.0.0.0 0.255.255.255 any log
access-list 100 deny ip 172.16.0.0 0.15.255.255 any log
access-list 100 deny ip 192.0.2.0 0.0.0.255 any log
access-list 100 deny ip 192.168.0.0 0.0.255.255 any log
access-list 100 deny ip 14.0.0.0 0.255.255.255 any log
access-list 100 deny ip 169.254.0.0 0.0.255.255 any log
access-list 100 deny ip 198.18.0.0 0.0.255.255 any log
access-list 100 deny ip 66.238.29.0 0.0.0.31 any log
! no routing protocols inbound (unless needed)
access-list 100 deny tcp any any eq bgp log
access-list 100 deny tcp any eq bgp any log
access-list 100 deny ipinip any any
access-list 100 deny gre any any
access-list 100 deny pim any any
access-list 100 deny 90 any any
access-list 100 deny ospf any any log
access-list 100 deny eigrp any any log
access-list 100 deny udp any eq rip any log
access-list 100 deny udp any any eq rip log
access-list 100 permit now begins your permits…if any

Notes:
192.0.2.0 0.0.0.255 any log (range known to be used exploit default pw on WLA devices)
4.0.0.0 0.255.255.255 any log (Known as Net-14, a Public use network, possibly used by attackers)
69.254.0.0 0.0.255.255 any log (RFC2026 Link Local)
198.18.0.0 0.0.255.255 any log (block for benchmark tests of network interconnect devices, RFC2544)