18.6 Managing Multiple Keys

It is not uncommon for multiple private keys to reside on a client system, each providing access to a different server. There are a number of options for selecting a specific key when establishing a connection. It is possible, for example, to specify the private key file to be used when launching the ssh client as follows:

$ ssh -l neilsmyth -i ~/.ssh/id_work 35.194.18.119

Alternatively, the SSH client user configuration file may be used to associate key files with servers. The configuration file is named config, must reside in the .ssh directory of the user’s home directory and can be used to configure a wide range of options including the private key file, the default port to use when connecting, the default user name, and an abbreviated nickname via which to reference the server. The following example config file defines different key files for two servers and allows them to be referenced by the nicknames home and work. In the case of the...