VPN With Pre-Shared Keys - Page 4
One advantage of using the PIX Firewall is that it has become a standard within the industry. As time passes, your business might acquire or become acquired by another company. To provide connectivity, you are faced with two choices: enabling VPNs over the Internet or using dedicated connections. Because one of the benefits of the PIX box is to allow secure VPNs, this section explores how to set up two PIX Firewalls between different locations through the Internet.
In this scenario, shown in Figure 4-10, assume that both companies trust each other totally. This means that you will not filter any traffic between the sites, and all hosts on both sites will be able to see all hosts on the other site. The peers use ISAKMP in Phase 1 to negotiate an IPSec connection in Phase 2.
As shown in Figure 4-12, the main office uses an internal IP address of 10.1.1.1/24 with an IP address of 172.30.1.1 on the outside interface. The branch office uses an internal IP address of 10.2.1.1/24 and an IP address of 172.30.2.1 on the outside interface. The following is the configuration for the PIX Firewall at the main office. After the configuration, you will see a discussion of the commands used.
hostname mainofficepix nameif ethernet0 outside security0 nameif ethernet1 inside security100 interface ethernet0 auto interface ethernet1 auto mtu outside 1500 mtu inside 1500 ip address outside 172.30.1.1 255.255.255.0 ip address inside 10.1.1.1 255.255.255.0 access-list 100 permit ip 10.1.1.0 255.255.255.0 10.2.1.0 255.255.255.0 nat (inside) 0 access-list 100 sysopt connection permit-ipsec crypto ipsec transform-set maintransformset esp-des esp-md5-hmac crypto map mymap 10 ipsec-isakmp crypto map mymap 10 match address 100 crypto map mymap 10 set peer 172.30.2.1 crypto map mymap 10 set transform-set maintransformset crypto map mymap interface outside isakmp enable outside isakmp key mysharedkey address 172.30.2.1 netmask 255.255.255.255 isakmp policy 10 authentication pre-share isakmp policy 10 encryption des isakmp policy 10 hash md5 isakmp policy 10 group 1 isakmp policy 10 lifetime 768All of the preceding commands have been discussed previously within this chapter. There are only a few new items that you need to watch carefully to ensure that this configuration will work.