For example, an authentication protocol might be used to establish the identities of the server and client while a separate messaging protocol might be used to exchange data. If there is a weakness in a protocol used by the client and server, an attacker might take advantage of this to perform various types of attacks. For example, if the attacker is able to manipulate an authentication protocol, the attacker may be able spoof other clients or servers. If the attacker is able to manipulate a messaging protocol, the may be able to read sensitive information or modify message contents. This attack is often made easier by the fact that many clients and servers support multiple protocols to perform similar roles. For example, a server might support several different authentication protocols in order to support a wide range of clients, including legacy clients. Some of the older protocols may have vulnerabilities that allow an attacker to manipulate client-server interactions.