Escape Characters

It is possible to control the SSH client while being logged in to a server:

Cloning Perl Arrays

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SSH Agent

The SSH agent stores unencrypted private keys to help you log in to servers without supplying your private key’s passphrase during retries.

Regenerating a Public Key

To regenerate your public key from the private key:

Perl Variable Aliases

When a variable is passed by value, Perl does not create a copy of the contents to build @_ but, rather, creates an alias to the contents of the original variable. Therefore, a memory blow-up is caused by reading from @_.

Cross Compiling Hint for Linux From Scratch has a new Maintainer

The crosscompiling hint is now maintained by Ted Bullock.


For a series of measurements $x_i = x_1, \dots, x_n$, it is useful to examine the magnitude of a certain fraction of the number of values.

Agent Forwarding

When logging into different hosts and over several hops generating key pairs and distributing public keys becomes a hassle with each additional host. At the same time security (i.e. key integrity and authentication) becomes a problem because breaking into one of your hosts might possibly compromise your private key and allow the attacker to login to one or more of the hosts you’re using.


keychain is a manager for the SSH agent. It ensures that there is a single running SSH agent which can be used from several shells at the same time.

Session Multiplexing

Although the OpenSSH client supports session multiplexing as of version 3.9, I understand that the server offers the support for some time. It allows several logins to share the same session and therefore the same login credentials. You will not have to authenticate everytime you open a session.