In this lesson we’ll take a look how to configure remote access IPsec VPN using the Cisco VPN client. This allows remote users to connect to the ASA and access the remote network through an IPsec encrypted tunnel.
The remote user requires the Cisco VPN client software on his/her computer, once the connection is established the user will receive a private IP address from the ASA and has access to the network.
The Cisco VPN client is end-of-life and has been replaced by the Cisco Anyconnect Secure Mobility Client. It’s not supported any more but still widely in use nowadays.
This is the topology that we will use for this example:
Many companies have multiple remote offices which need secure network connectivity with the headquarters or between them. This can be achieved by using a site-to-site VPN setup which allows offices in multiple fixed locations to establish secure connections and share resources with each other over a public network such as the Internet. Cisco ASA supports the IPsec protocol for configuring an site-to-site VPN tunnel. IPsec works by authenticating and encrypting each IP packet of a communication session and uses the Internet Key Exchange (IKE) protocol to negotiate and establish a secure VPN tunnel. The original IKE version 1 is defined in RFC 2409 and the IKE version 2 (IKEv2) is defined in RFC 5996. Cisco introduced support for IKEv2 beginning with ASA version 8.4 but in this article we will focus only on the legacy IKEv1 implementation.
Normally when a routing device receives a packet it decides where to forward it based on the destination address of the packet. Policy Based Routing (PBR) is a mechanism which allows you forward packets based on policies manually defined by network administrators. A good use case for PBR is when a company which has multiple outside connections to different ISPs needs to control how traffic can be distributed across these connections. Compared to traditional routing PBR allows you to implement routing policies based on different criterias like source or destination address, source or destination port, protocol, size of the packet, packet classification and so on. Cisco introduced this feature on Cisco ASA beginning with version 9.4(1). Let’s dive into the PBR configuration.
In modern datacenters one of the most important things that needs to be addressed is uptime. Cisco ASA offers high availability mechanisms like failover in order to provide network uptime and redundancy. In order to configure failover we need two identical ASA devices connected to each other through a dedicated failover link and, optionally, a stateful failover link. There are two different failover modes that are supported on the ASA platform: active/standby and active/active. In this article we will focus only on configuring active/standby failover. In an active/standby failover setup only one unit called the active unit is passing traffic. The standby unit is used as a backup of the active unit and only accepts management connections (all transit traffic is dropped). When the active unit fails, it changes to the standby state while the standby unit changes to the active state.