Internet Key Exchange (IKE or IKEv2) is the protocol used to set up a security association (SA) in the IPsec protocol suite. IKE builds upon the Oakley protocol and ISAKMP. IKE uses X.509 certificates for authentication which are either pre-shared or distributed using DNS (preferably with DNSSEC) and a Diffie-Hellman key exchange to set up a shared session secret from which cryptographic keys are derived.
Internet Key Exchange (IKE) Internet key exchange allows communicating partners to prove their identity to each other and establish a secure communication channel, and is applied as an authentication component of IPSec.
IKE uses two phases:
Phase 1: In this phase, the partners authenticate with each other, using one of the following:
Shared Secret: A key that is exchanged by humans via telephone, fax, encrypted e-mail, etc.
Public Key Encryption: Digital certificates are exchanged.
Revised mode of Public Key Encryption: To reduce the overhead of public key encryption, a nonce (a Cryptographic function that refers to a number or bit string used only once, in security engineering) is encrypted with the communicating partner's public key, and the peer's identity is encrypted with symmetric encryption using the nonce as the key. Next,
IKE establishes a temporary security association and secure tunnel to protect the rest of the key exchange. Phase 2: The peers' security associations are established, using the secure tunnel and temporary SA created at the end of phase 1.
The following reference(s) were used for this question:
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third
Edition ((ISC)2 Press) (Kindle Locations 7032-7048). Auerbach Publications. Kindle
Edition.
and
RFC 2409 at http://tools.ietf.org/html/rfc2409
and
http://en.wikipedia.org/wiki/Internet_Key_Exchange

A proxy server is a server that sits between a client and server application, such as a Web browser and a source web server. It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the original source web server. Firewalls usually provides this kind of services to have more control over user request and allow / deny the traffic of those through the gateway. At this time the most common Proxy server is for HTTP protocol, we can also have proxies for SMTP and FTP.

The right to audit the MSSP's security process should be included in the outsourcing contract.
This allows the organization to verify that the MSSP is meeting the requirements set out in the contract and is providing the level of service that has been agreed upon. The organization should also ensure that the contract includes provisions for reporting on security incidents and breach notifications. While including an overview of equipment and having an executive manager responsible for information security are important considerations, they are not as critical as the right to audit the MSSP's security process.

Data trust frameworks establish agreed-upon technical, legal, and governance standards among multiple participating organizations, defining how data can be securely shared, accessed, and used across organizational boundaries while maintaining appropriate privacy, security, and compliance safeguards, increasingly important in collaborative ecosystems such as healthcare research consortia or industry information-sharing groups.