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IOS firewall question

jaguarrt1978
Community Member

Hi,

I am trying to configure firewall on our new cisco 1711 router. Whenever I try to put an access list for fastethernet0(interface that connects to my service provider) it stops all the internet traffic inbound/outbound. My internal network IP is 10.10.0.0 255.255.0.0. Am I doing anything wrong?

access-list 101 permit udp host 4.2.2.4 eq domain host x.x.x.x

access-list 101 deny ip 10.10.0.0 0.0.255.255 any

access-list 101 permit icmp any host x.x.x.x echo-reply

access-list 101 permit icmp any host x.x.x.x time-exceeded

access-list 101 permit icmp any host x.x.x.x unreachable

access-list 110 permit tcp any 10.10.0.10 255.255.0.0 eq www

access-list 101 deny ip 10.0.0.0 0.255.255.255 any

access-list 101 deny ip 172.16.0.0 0.15.255.255 any

access-list 101 deny ip 192.168.0.0 0.0.255.255 any

access-list 101 deny ip 127.0.0.0 0.255.255.255 any

access-list 101 deny ip host 255.255.255.255 any

3 Replies 3

sstudsdahl
Level 8
Level 8

One thing to remember with ACL's is that there is an implicit "deny any any" as the final entry and it is not shown in the configuration.

Try adding:

access-list 101 permit ip any any

as the last line of your ACL. This will block (with the exception of your permits) everything that you have defined above it and will permit everything else.

Steve

csoans
Level 1
Level 1

could you post the entire config, remove any info you feel is sensitive, this will help analyze this problem better.

Regards

Chris

version 12.3

no service pad

service tcp-keepalives-in

service tcp-keepalives-out

service password-encryption

service compress-config

service sequence-numbers

!

hostname router

!

boot-start-marker

boot-end-marker

!

logging buffered 51200 debugging

logging console critical

enable secret 5 xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

!

username xxxx privilege 15 secret 5 xxxxxxxxxxxxxxxxxxxxxxxxxxx

mmi polling-interval 60

no mmi auto-configure

no mmi pvc

mmi snmp-timeout 180

no aaa new-model

ip subnet-zero

no ip source-route

!

!

ip dhcp excluded-address 10.10.0.255 10.255.255.254

ip dhcp excluded-address 10.10.0.1 10.10.0.9

!

ip dhcp pool sdm-pool1

import all

network 10.10.0.0 255.255.0.0

default-router 10.10.0.1

!

!

ip tcp synwait-time 10

ip domain name xxxxxxxx.com

ip name-server 4.2.2.4

no ip bootp server

ip cef

ip ids po max-events 100

ip ssh time-out 60

ip ssh authentication-retries 2

no ftp-server write-enable

!

!

!

!

!

!

!

!

interface Null0

no ip unreachables

!

interface FastEthernet0

ip address x.x.x.x x.x.x.x

ip access-group 101 in

ip verify unicast reverse-path

no ip redirects

no ip unreachables

no ip proxy-arp

ip nat outside

ip virtual-reassembly

ip route-cache flow

duplex auto

speed auto

no cdp enable

!

interface FastEthernet1

no ip address

no cdp enable

!

interface FastEthernet2

no ip address

no cdp enable

!

interface FastEthernet3

no ip address

no cdp enable

!

interface FastEthernet4

no ip address

no cdp enable

!

interface Vlan1

ip address 10.10.0.1 255.255.0.0

ip access-group 102 in

no ip redirects

no ip unreachables

no ip proxy-arp

ip nat inside

ip virtual-reassembly

ip route-cache flow

ip tcp adjust-mss 1452

!

interface Async1

no ip address

no ip redirects

no ip unreachables

no ip proxy-arp

!

ip default-gateway 10.10.0.1

ip classless

ip route 0.0.0.0 0.0.0.0 x.x.x.x

no ip http server

ip http authentication local

ip http secure-server

ip nat inside source list 1 interface FastEthernet0 overload

ip nat inside source static tcp 10.10.0.10 80 interface FastEthernet0 80

ip nat inside source static tcp 10.10.0.10 443 interface FastEthernet0 443

!

!

!

logging trap debugging

access-list 1 permit 10.10.0.0 0.0.255.255

access-list 101 permit udp host 4.2.2.4 eq domain host x.x.x.x

access-list 101 deny ip 10.10.0.0 0.0.255.255 any

access-list 101 permit icmp any host x.x.x.x echo-reply

access-list 101 permit icmp any host x.x.x.x time-exceeded

access-list 101 permit icmp any host x.x.x.x unreachable

access-list 101 permit tcp any 10.10.0.10 255.255.0.0 eq www

access-list 101 permit tcp any 10.10.0.10 255.255.0.0 eq 443

access-list 101 deny ip 10.0.0.0 0.255.255.255 any

access-list 101 deny ip 172.16.0.0 0.15.255.255 any

access-list 101 deny ip 192.168.0.0 0.0.255.255 any

access-list 101 deny ip 127.0.0.0 0.255.255.255 any

access-list 101 deny ip host 255.255.255.255 any

access-list 102 deny ip 192.168.0.0 0.0.255.255 any

access-list 102 deny ip 172.16.0.0 0.15.255.255 any

access-list 102 deny ip 169.254.92.0 0.0.0.255 any

access-list 102 deny ip any 192.168.0.0 0.0.255.255

access-list 102 deny ip any 172.16.0.0 0.15.255.255

access-list 102 deny ip any 169.254.92.0 0.0.0.255

access-list 102 permit ip 10.10.0.0 0.0.255.255 any

access-list 102 permit ip any any

access-list 103 permit ip 10.10.0.0 0.0.255.255 any

access-list 103 deny ip any any

no cdp run

!

!

control-plane

!

banner login ^CAuthorized access only!

Disconnect IMMEDIATELY if you are not an authorized user!^C

!

line con 0

login local

transport output telnet

line 1

stopbits 1

speed 115200

flowcontrol hardware

line aux 0

login local

transport output telnet

line vty 0 4

access-class 103 in

login local

transport input telnet ssh

transport output none

line vty 5 15

access-class 103 in

login local

transport input telnet ssh

transport output none

!

scheduler allocate 4000 1000

scheduler interval 500

end