You bet:
crypto isakmp policy 1
---this command creates the isakmp policy '1'---
hash md5
---this command sets the crypto hash to 'md5'---
authentication pre-share
---This command sets the tunnel authentication type to 'pre-share' (since we are using a key)---
crypto isakmp key blahblah address a.b.c.d no-xauth
--This command sets the isakmp key to for your peer to 'blahblah' (it can be anything you want, you just have to match it on the other side of the tunnel)---
!
!
crypto ipsec transform-set to_vpn esp-des esp-md5-hmac
---This command sets the ipsec transform set named 'to_vpn' (it can be any name you want). These transform sets are the encryption and hash types allowed for this tunnel; i.e. 3des, des, md5, etc. Thes transform-sets have to match on both sides of the tunnel---
!
crypto map to_vpn 10 ipsec-isakmp
---This command creats the crypto map 'to_vpn'it can be any name you choose. 10 is the map sequence number and ipsec-isakmp is the type of crypto map---
set peer a.b.c.d
---This is your set statement for the peer, you configure this with the IP address of your router at the other end of the tunnel---
set transform-set to_vpn
---This command sets the transform set to the above configured transform-set 'to_vpn'---
match address 100
--This is the map match statement that applies the above set statements to what matches the ACL created below---
!
interface Ethernet1/0
ip address w.x.y.z 255.255.255.0
---IP address of your outside interface---
crypto map to_vpn
---This is your router external interface config. The 'crypto map to_vpn' statement applies the crypto map 'to_vpn' to the outside interface of your router---
!
access-list 100 remark LAN2LAN Match Address
access-list 100 permit ip w.x.y.z 0.0.0.255 a.b.c.d 0.0.255.255
---This is an ACL that the crypto map uses to match what addresses to 'tunnel'. This is an advanced ACL so it has to match source and destination---
Also, here is a link that may help you if you want to do dynamic client tunnels as well as lan2lan tunnels: http://www.cisco.com/en/US/customer/tech/tk583/tk372/technologies_configuration_example09186a00800949ef.shtml#configs
and another
http://www.cisco.com/en/US/customer/products/ps6350/products_configuration_guide_chapter09186a008049d04c.html
HTH,
Jason
