Which two statements are true regarding the use of the ssh-agent and ssh-add commands?
A.
The ssh-agent is used to hold private keys.
B.
The ssh-add command may ask for a passphrase each time the same key is required by the
same user in the same shell.
C.
The ssh-agent is used to hold only public keys.
D.
The ssh-add command asks for the passphrase only the first time a key is required by the same
user in the same shell.
E.
The ssh-add command retries the most recently saved passphrase if multiple key files are
used.
Explanation:
A (not C): If you want to omit passphrase and password entry when you are using
Solaris Secure Shell, you can use the agent daemon. Use the ssh-agent command at the
beginning of the session. Then, store your private keys with the agent by using the ssh-add
command.
D: Add your private key to the agent daemon.
The ssh-add command adds your private key to the agent daemon so that subsequent Secure
Shell activity does not prompt you for the passphrase.
myLocalHost% ssh-add
Enter passphrase for /home/johndoe/.ssh/id_rsa:
Identity added: /home/johndoe/.ssh/id_rsa(/home/johndoe/.ssh/id_rsa)
myLocalHost%
A, D
A,D
A & E
Excerpt from ssh-add’s man page:
If any file requires a passphrase, ssh-add asks for the passphrase from
the user. The passphrase is read from the user’s tty. ssh-add retries
the last passphrase if multiple identity files are given.
D,E
A, D
https://unix.stackexchange.com/questions/72552/whats-the-purpose-of-ssh-agent/72555
ssh-agent is a program to hold private keys used for public key authentication (RSA, DSA, ECDSA). The idea is that ssh-agent is started in the beginning of an X-session or a login session, and all other windows or programs are started as clients to the ssh-agent program. Through use of environment variables the agent can be located and automatically used for authentication when logging in to other machines using ssh(1).
http://sshkeychain.sourceforge.net/mirrors/SSH-with-Keys-HOWTO/SSH-with-Keys-HOWTO-6.html
The little program ssh-agent does you a favor by managing your keys for you. You enter the passphrase once, and after that, ssh-agent keeps your key in its memory and pulls it up whenever it is asked for it.