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New Member

managing routers after a firewall using aaa


Please i would like to manage my internet routers using tacacs. However, this has not been possible cos a firewall blocks the traffic. Can anybody advice me on how to achieve this?



Re: managing routers after a firewall using aaa


First, you need to allow router and ACS to reach each other.

Configure your internet router with appropriate aaa configuration as desired. Refer below as an example:


Router FastEthernet: xx.xx.xx.5/24

Firewall Outside IP: xx.xx.xx.6/24

Firewall Inside IP:

Internal ACS:


aaa new-model

aaa authentication login TELNET group tacacs+ local

aaa authentication login CONSOLE local

aaa authentication enable default enable

aaa authorization exec default group tacacs+ local

aaa authorization network default group tacacs+ if-authenticated local

aaa accounting exec default start-stop group tacacs+

aaa accounting network default start-stop group tacacs+

tacacs-server host xx.xx.xx.10 timeout 10 key secretkey


1. Map internal ACS to a public IP, or use port re-directio if you don't have enough public (outside) IP to be used.

static (inside,outside) xx.xx.xx.10 netmask

For security reason, you can limit session to tacacs+ from the router by adding any number like "10 5" after the netmask, e.g

static (inside,outside) xx.xx.xx.10 netmask 10 5

10 = half open session (embryonic level)

5 = max connection to ACS (thru tacacs+ port)

2. Create ACL on outside interface to allow Router's fastethernet interface IP to reach internal ACS via xx.xx.xx.10 IP via tacacs+ port. Bind the ACL to outside interface.

Also, for testing purposes, enable PING/ICMP from router to the ACS. This can be disable later on as desired.

access-list outside permit tcp host xx.xx.xx.5 host xx.xx.xx.10 eq tacacs

access-list outside permit icmp host xx.xx.xx.5 host xx.xx.xx.10 any any

access-group outside in interface outside

3. Add the Router's FastEthernet IP as AAA client to ACS. Refer to the following config guide:

Make sure you select tacacs+ as the authentication protocol, use the same key as configured in router.



New Member

Re: managing routers after a firewall using aaa

Thanks AK, Will try and get back to you.