IPsec/en

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We make a cisco 2811 router into an ipsec host.

General info

WAN interface: fa0/0

LAN interface: fa0/1

Configuring

First we setup our network connections

interface FastEthernet0/0
 description *allworkandnoplaymakestranslatoradullboy*
 ip address 10.10.10.2 255.255.255.0
 ip nat outside
 ipv6 ospf cost 1
 crypto map ipsecmap

interface FastEthernet0/1
 description *areallydullboy*
 ip address 192.168.100.1 255.255.255.0
 ip nat inside

We enable aaa new-model simply by running the command

 aaa new-model

We aren't talking about an AA-club, AAA stand for authentication-authorization-accounting. It is often used when fiddling with authentication and the likes.

Now we define logins to be locally sourced and not for instance from a radius server.

 aaa authentication login IPsecE local
 aaa authorization network IPsecO local

We tell the router to ALWAYS use esp-3des esp-md5-hmac encryption.

 crypto ipsec transform-set Example esp-3des esp-md5-hmac

We create a dynamic field which makes ipsec use example encryption.

 crypto dynamic-map TestMap 7
 set transform-set Example 

We make a isakmp policy which defines the connection's tweaks:

 crypto isakmp policy 7
 encr 3des
 authentication pre-share
 group 2

Then we create a group for ipsec

 crypto isakmp client configuration group Testers
 key Key
 pool testpool
 netmask 255.255.255.0

We make an address space by the name testpool which gives addresses to clients.

 ip local pool testpool 192.168.70.20 192.168.70.30

Again we make a map and inspect the work we have done.

 crypto map ipsecmap client authentication list IpsecE
 crypto map ipsecmap isakmp authorization list IpsecO
 crypto map ipsecmap client configuration address respond
 crypto map ipsecmap 7 ipsec-isakmp dynamic TestMap

We still need to setup NAT:

 ip access-list extended nonat
 deny ip 192.168.100.0 0.0.0.255 192.168.70.0 0.0.0.255
 permit ip any any

ip nat inside source list nonat interface FastEthernet0/0 overload

We still make a user.

 username johannes password 0 Qwerty1

Now we test our VPN

We put the information in their place. The picture has the credentials from the original Finnish manual but you can just substitute them with the ones from this manual's configuration which we did above. Testers / Key / 10.10.10.2 / johannes / Qwerty1

And we're in.