is a ccna certification worth it

is a ccna certification worth it.Secure Shell (SSH) encrypts the traffic between the client and the SSH server. SSH was developed as a security tool to replace Telnet, which does not support encryption and is highly susceptible to man-in-the-middle attacks. Network administrators often use SSH to protect traffic between the management client and the managed network device when accessing and managing network devices remotely.SSH both authenticates the remote computer with public key encryption and allows the remote computer to authenticate the user's identity. A variety of encryption algorithms (such as the RSA [Rivest, Shamir, and Adelman] algorithm, the Digital Signature Algorithm (DSA), and the Elliptic Curve Digital Signature Algorithm [ECDSA]) can be used to generate SSH keys. The basic components of an SSH system include an SSH server, an SSH client, and a key. The standard listening port for the SSH server is port TCP22. Various online sources can be consulted for detailed information related to developing an SSH solution. However, how to develop an SSH solution is beyond the scope of the SECFND exam.An attacker could use SSH to hide traffic, for example, by creating a reverse SSH tunnel from the compromised system to an external SSH server, hiding traffic destined for an external network and containing sensitive data. Figure 14-5 shows how a typical SSH session is created.Remote HostCompany IntranetFigure 14-5 SSH VPN Example 14.2 Encryption and Tunneling 495Examples abound of attackers compromising a network and then initiating some sort of VPN session from the inside out. Let's say that Hak5's LANTurtleUSB adapter is used and configured to automatically initiate a reverse SSH tunnel to a cloud storage server, thus opening a back door within the victim's network that can access the cloud. Figure 14.6 shows the LAN Turtleo plugged into the laptop computerFigure 14-6 Hak5's LAN TurtleIt is very difficult for network administrators to locate the LANTurtle, because it is usually plugged into a trusted system and does not require an IP address to be configured to establish a reverse encryption tunnel. Figure 14.7 shows a LANTurtle plugged into an intranet server, which creates an encrypted tunnel to a remote attack server. In other words, the attacker has launched a physical attack that opens a back door on the internal network to an external malicious host.Attacker-controlled cloud server