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Tag Archives: users

July, 2010

  • 16 July

    How to Fix an Open Relay in Postfix

    postfix

    As I have been reiterating all week, an open relay is a bad idea. If your mail server is left open, anyone can use your SMTP service to send mail, and spammers will use it. This can result in your server being blacklisted and extraneous use of system resources that …

June, 2010

  • 25 June

    How To Create Multiple New Users

    In Linux, the most common method used to create new users is to use the “adduser” command. This is fine when you need to add one or even a few users, but if you need to add numerous (i.e. 50, 100, or even 500), typing in the adduser command repeatedly …

April, 2010

  • 12 April

    Server redundancy

    In an ideal world, you get what you want all the time. The shopping lines are always short, the traffic is always light, and there are more jobs than there are people to fill them. Unfortunately, we do not live in an ideal world, and just like a street can …

  • 1 April

    To chmod or not to chmod

    When installing scripts on a server, there is a tendency of both developers (in their instructions) and users to be overly generous in dishing out file permissions. In Linux, file permissions can be manipulated with the “chmod” command. For example, a script may require write access to a temporary directory, …

February, 2010

  • 15 February

    How to list all users in Linux

    Question: How do I see all of the users that have accounts on my server? Answer: In a previous post, we covered the “who” command, which will tell an administrator which users are currently logged into the system, but another important thing to know about your server is which users …

January, 2010

  • 14 January

    How to prevent users from reusing old passwords in Linux

    In a previous blog post, we learned how to force users to change their passwords on a regular basis. This prevents them from keeping the same password forever, but it does not prevent them from alternating between the same two passwords or between a handful of them. Fortunately, PAM, Linux‘s …

November, 2009

  • 3 November

    Changing file ownership in Linux

    There are many situations when you may need to change the ownership of files, especially if you are operating a virtual private server or dedicated server. For example, you may install something for a website as root but then need to set ownership of the file to the local user. …