CCNP Security 350-701 Book

ExplanationThe command crypto isakmp key cisco address 1.2.3.4 authenticates the IP address of the 1.2.3.4 peer by using the key cisco. The address of “0.0.0.0” will authenticate any address with this key

The Southbound API is used to communicate between Controllers and network devices.

ExplanationExplanationHow To Troubleshoot ISE Failed Authentications & AuthorizationsCheck the ISE Live LogsLogin to the primary ISE Policy Administration Node (PAN).Go to Operations > RADIUS > Live Logs(Optional) If the event is not present in the RADIUS Live Logs, go to Operations > Reports > Reports >Endpoints and Users > RADIUS AuthenticationsCheck for Any Failed Authentication Attempts in the Log

3DES is a symmetric-key block cipher that applies the DES algorithm three times to each data block. It was developed to improve the security of DES, which has a small key size and is vulnerable to brute-force attacks. 3DES encrypts traffic by using three different keys, each 56 bits long, to perform three rounds of encryption on the plaintext. The encryption process can be described as follows:

• Encrypt the plaintext with the first key (K1).
• Decrypt the result with the second key (K2).
• Encrypt the result again with the third key (K3).

The final ciphertext is the output of the third encryption. The decryption process is the reverse of the encryption process, using the same keys in reverse order:

• Decrypt the ciphertext with the third key (K3).
• Encrypt the result with the second key (K2).
• Decrypt the result again with the first key (K1).

The final plaintext is the output of the third decryption. 3DES is more secure than DES because it uses a longer effective key length of 168 bits (56 x 3), which makes brute-force attacks more difficult. However, 3DES is also slower than DES because it requires three times more computations. Moreover, 3DES has some weaknesses, such as the meet-in-the-middle attack, which can reduce the effective key length to 112 bits. Therefore, 3DES is not recommended for new applications and has been deprecated by NIST since 201712

References := 1: NIST Special Publication 800-67 Revision 2 Recommendation for the Triple Data Encryption Algorithm (TDEA) Block Cipher 2: What is 3DES encryption and how does DES work? | Comparitech