4.12 Reusing passwords for several connections

To avoid repeated prompts for passwords, consider native caching mechanisms, such as ssh-agent for ssh-like methods, or pageant for plink-like methods.

TRAMP offers alternatives when native solutions cannot meet the need.

4.12.1 Using an authentication file

The package auth-source.el, originally developed for No Gnus, reads passwords from different sources, See (auth)auth-source. The default authentication file is ~/.authinfo.gpg, but this can be changed via the variable auth-sources.

A typical entry in the authentication file:

machine melancholia port scp login daniel password geheim

The port can take any TRAMP method (see Inline methods, see External methods). Omitting port values matches all TRAMP methods.

Setting auth-source-debug to t to debug messages.

4.12.2 Caching passwords

TRAMP can cache passwords as entered and reuse when needed for the same user or host name independent of the access method.

password-cache-expiry sets the duration (in seconds) the passwords are remembered. Passwords are never saved permanently nor can they extend beyond the lifetime of the current Emacs session. Set password-cache-expiry to nil to disable expiration.

Set password-cache to nil to disable password caching.

Implementation Note: password caching depends on password-cache.el package. TRAMP activates password caching only if TRAMP can discover, while Emacs is loading, the package through load-path.