Data in transit is vulnerable to eavesdropping if the network devices are not properly configured. If the users require additional security, they can use IPSec, which provides a means of encrypting and authenticating traffic when the traffic is sent from the source to the destination. We covered the IPSec encryption of the links in Chapter 6, Understanding and Configuring WAN technologies. IPSec is also used by remote users when they access the network remotely by logging into the network through a VPN. This configuration was discussed in Chapter 7, Understanding and Configuring Data Center Technologies.