Unix security: Difference between revisions

Revision as of 11:23, 16 October 2022

Revision as of 02:37, 4 May 2023

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nickname:password_hash:UserID:GroupID:Complete_Name:home_dir:shell_bin

An example would be:

{{sxhl|2=unixconfig|xfze:$$1zuW2nX3sslp3qJm9MYDdglEApAc36r/:1000:100:Daniel Ernesto Ortiz Costa:/home/xfze:/bin/bash}}

Since all users must have read access to the <code>/etc/passwd</code> file to do many common tasks (<code>ls -l /home</code> will use <code>/etc/passwd</code> to map UIDs to login names for example), anyone could also read the password hashes of other users. To solve this problem, the file <code>[[password shadowing|/etc/shadow]]</code> was created to store the password hashes, with only [[root]] having read access. Under password shadowing, the 2nd field ([[key derivation function|password hash]]) is replaced by an 'x' which tells the system to retrieve the corresponding user's password via the <code>/etc/shadow</code> file.

The <code>/etc/shadow</code> file often only contains values for the first two fields:

{{sxhl|2=unixconfig|xfze:$$1zuW2nX3sslp3qJm9MYDdglEApAc36r/:::::}}

The remaining fields in the <code>/etc/shadow</code> file include: