Working with ISO from the Linux Command Line
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Posted on August 1, 2011 by

If you have wondered how to create an iso from the command line, it is very simple.  You just need to use the following commands:

mkisofs -o <name of iso>.iso <directory to be iso>

To burn an ISO from the command-line many people do a DD, this doesn’t always work since it is technically not the correct way to do it.  To do it the proper way you would need to run the following commands:

  1. Determine the Device ID number by running the following command:

    cdrecord -scanbus

    * The device ID number will be x,x,x on the row which lists the CD/DVD drive you will be using.

  2. Next you will want to do the actual burning of the ISO to that device using the following command:

cdrecord -v dev=<Device ID from the scanbus command> <ISO to burn>.iso

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Unlock An Account
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Posted on August 1, 2011 by

To unlock a user in Linux is quite easy you just need to run the following command:

passwd -u <account>

This will unlock the account which has expired, but if you have turned on the advanced PAM Account Auditing you will also need to reset their account using the following command:

/sbin/pam_tally2 –user <account> –reset

This will reset the number of times they have incorrectly logged in so the account can be used again.

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Fedora 15 Default Run-level
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Posted on July 11, 2011 by

There were many changes made to Fedora 15, one of the ones that I keep running into is how to change the default run-level of your box.  I use Fedora as a server OS in many situations because it offers some advanced features which CentOS either has out of date or doesn’t even include.  Since often these boxes run headless I just set them to boot to run-level 3.  The command below tells you how to do it:

ln -s /lib/systemd/system/<target name>.target /etc/systemd/system/default.target

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Mounting folders through SSH
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Posted on July 7, 2011 by

One of the first rules of security is to not have any ports open which you do not need to have open.  That is also pretty common sense.  One problem you run into though is you still need to access data from one machine on another.  Samba is generally used for file sharing but since it follows the windows standard for file sharing it announces your shares to anyone who asks.

If it is just you accessing your files you can actually mount a folder from another system using sshfs.  Sshfs is available in all of the major distro’s repositories so it should be easy to find.

The first step is to just create a folder which you want to use as a mount point.  Once you do that you just use the following command:

sshfs <user>@<machine>:/path/on/remote/system /local/path

After you do that your local folder will now display the contents of your remote folder.

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Setting a Lock-out Policy
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Posted on June 29, 2011 by

Setting a lock out policy in CentOS or Fedora is very easy.

  1. edit /etc/pam.d/system-auth

auth required pam_tally.so onerr=fail no_magic_root
account required pam_tally.so deny=3 unlock_time=3600 no_magic_root reset

onerr=fail if there is a problem opening the file for some reason fail login
no_magic_root this means if the module is called with a uid=0 then the counter is incremented, this is for launching services
deny=3 lockout will occur if the user exceeds 3 logins
reset means if the sign in correctly then the account will be reset
unlock_time=3600 number of seconds before unlock

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