Something

!
crypto isakmp policy 10
 encr 3des
 hash md5
 authentication pre-share
 group 2
 lifetime 28800
crypto isakmp key thekey address 4.3.2.1
!
!
crypto ipsec transform-set to_ipsec_peer esp-3des esp-md5-hmac

!
crypto map ipsec_peer_map 10 ipsec-isakmp
 set peer 4.3.2.1
 set transform-set to_ipsec_peer
 set pfs group2
 match address 112
!
!
interface Tunnel0
 no ip address
 keepalive 10 5
 tunnel source 11.12.13.14.15
 tunnel destination 1.2.3.4
 crypto map ipsec_peer_map
!
interface Loopback2
 ip address 11.12.13.14.15 255.255.255.0
 crypto map ipsec_peer_map
!
access-list 112 permit ip 1.2.3.0 0.0.0.255 7.8.9.0 0.0.0.255
access-list 112 permit ip 7.8.9.0 0.0.0.255 1.2.3.0 0.0.0.255