simon.schönbeck.dk

Tag: error

  • Apache: DocumentRoot does not exist. Why SELinux?

    Once more SELinux has been playing up with the normal operations of a box. During the installation and set up of an Apache instance and a few virtual hosts I simply could not get around the dreaded error message:

    Starting httpd: Warning: DocumentRoot [/home/www/myhost] does not exist

    No matter which permissions and owners were given to the directories or files related the error still came up hindering the Apache httpd service to start. Obviously the path was correct, copied and pasted, to exclude any spelling issues.

    After experiencing similar conundrums in the past I had a slight suspicion regarding SELinux, which comes enabled by default on Fedora, may have been blocking access to the directory somehow.

    A bit of searching did confirm that SELinux indeed also intervened at this level blocking Apache’s normal operations. I fully understand and agree with the goal of SELinux, but it is simply too big a compromise between security and usability. As Theodore Tso pretty much summarises it:

    SELINUX is so horrible to use, that after wasting a large amount of time enabling it and then watching all of my applications die a horrible death since they didn’t have the appropriate hand-crafted security policy, caused me to swear off of it. For me, given my threat model and how much my time is worth, life is too short for SELinux.

    SELinux stays disabled again…

  • Error: Could not open the local file – FTP madness!

    Trying to move some automatic backups from one location to another became a bit of a struggle recently. The backups are created automatically and uploaded to a file server at a scheduled pattern. From this file server I had to use some of the backups and tried to download them to my local machine. This is where the problem started.

    I am long time user of the excellent FTP client named FileZilla and very seldom experience any issues with it. But this time during the download process I kept receiving this weird error message:

    Error:    Could not open the local file path/filename
    Error:    Download failed

    I initially thought about some permission problems like no read access until I swiftly realised it was actually on the local side the issue was and not on the server. This just made no sense as obviously why would it want to open the file when it actually had to create the file instead. I tried to download the backups to different locations on the hard disks, even external ones as well, to see if oddly enough they had magically become write protected. This was not successful and I started to think of the directory structure as downloading the individual file worked just fine.

    So to summarise:

    1. Downloading the directory containing the backups did not work.
    2. Downloading each individual file inside the directory worked as expected.

    Very strange indeed…

    I actually did not break it until the following morning when I woke up with the solution. I am not sure what happened as I would not dream about such a pity issue but I just woke up and Eureka!

    In hindsight it was really obvious what the problem was but at the point it just did not come to my mind.

    Linux and Windows have some dramatic differences and one of them is the fact that file and directory names under Windows are limited to certain characters while Linux pretty much takes it all. I was trying to download directories to a Windows XP PC with a colon (:) in the name, such as . This is incompatible with Windows and therefore FileZilla was not permitted to create such directories anywhere on the hard disks.

    Never use the following characters in file or directory names if you expect Windows compatibility:

    / \ : * ? " < > |