Answer -Pick any one cryptographic protocol (e.g., SSL, TLS, IKE, Kerberos, SSH, PPTP, WEP, WPA, TKIP etc.). In your initial discussion post, please explain the working and details of the protocol clearly (no copy+paste). Wikipedia is not acceptable. When responding to someone's post, please provide any missing details of the protocol that was explained, with particular emphasis on attacks/limitations of the protocol.

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SSH is an acronym for Secure Shell. It was invented by the founder of SSH Communications Security, Tatu Ylönen ("About," 2015). It is used as a secure way to connect remotely between two network devices ("Configuring Secure Shell on Routers and Switches Running Cisco IOS," 2007). Both of the network devices are authenticated by a certificate and an encrypted password. It uses public key cryptography with an International Data Encryption Algorithm (IDEA) algorithm by default (Rouse, 2015).

Three major components comprise SSH. One is the Transport Layer Protocol. It authenticates servers. The second is the User Authentication Protocol. It authenticates clients. The last is the Connection Protocol which divides the tunnel between the two network devices into channels ("The Secure Shell (SSH) Protocol Architecture," 2005). Once authentication is complete, SSH gives a user the ability to have command line access to a UNIX or Linux system ("Explanation of SSH (Secure Shell Access)," 2015).

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IPSec is a set of protocols developed by the  IETF (internet engineering task force) to support secure exchange of packets at the IP layer.  Ipsec has been deployed widely to implement virtual private networks.  There are two encryption modes supported by ipsec including transport mode and tunnel mode.  VPN's use the tunnel mode, which encrypts the payload and the header.  Transport mode only encrypts the payload but leaves the header less secure. (Beal, 2015) The sending and receiving devices need to be ipsec-compliant so that encryption and de-cryption can take place on both sides of the communication.  One additional note mentioned is that for IPsec to work, a public key is used through a protocol known as ISAKMP/Oakley. (Beal, 2015)

One compelling reason to move from IPv4 to IPv6 for internet use is that the framework for VPN is built into the IPv6 protocol for a more secure usage.