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Pages with category Transfer

  • Setup your interface for multiple IP addresses

    Today I got a new IP address for a server and I had to assign it to the same NIC as my current IP address.

    So?! How do you do that on a Debian or Ubuntu server?

    It is actually very simple. On Ubuntu you go to /etc/network and edit the interfaces file. It should already include a definition for eth0 (virtual machines will have something else than eth0).

      # The loopback network interface
      auto lo
      iface lo inet loopback
    
      # The primary network interface
      auto eth0
      iface eth0 inet static
            address 192.168.1.1
            ...
  • I've been looking around every now and then to try to understand how I could create a server that replies on the correct Ethernet port.

    The idea is simple, we have very powerful servers that can handle many requests, more requests that one Ethernet port can handle. In other words, we could have 2, 3, 4, probably even 10 Ethernet connections (it really depends on your application, of course: how much RAM you need, how much processing is necessary for each access, etc.)

    The solution is to use the ip command line which allows us to add default gateways for each ethernet card based on the ...

  • Yesterday I had a customer sending me emails from a different account from last time. That different account is a Yahoo! account so in general there is no problems with that.

    Yet, this one time it did not make it. One of my email filters failed. Namely, the DKIM filter. It uses the dkim library to check mail messages and make sure that they indeed originate from where they say they are from.

    It is an interesting concept. In the following figure I show the standard scenario of a hacker sending me spam and a valid domain sending me an email:

    As you can see, if I communicate with the ...

  • Today I wasted another hour or so in trying to get samba to work for one of my Windows computer so I could connect to one of my Linux computer. I knew that the installation was correct since I could log in with another computer/user that had worked for a long time. So... why would this one fail?

    Two things, for of all, I could see NOTHING happening in the logs. Really wondering why the default is to log close to nothing with such a non-secure piece of software, but that's a different question. I added the following to actually get about enough logs to understand what was happening:

    log ...
  • Lately, I noticed that I always had a clamav.inoc.net connection. I was wondering why... I did install clamav but I did not recall changing anything in Apache where I'd get requests from the outside that would look like clamav.

    The fact is I also installed freshclam. By default, that gives you a line like this in your netstat -a64 listing:

        tcp   383     0 halk:38272       clamav.inoc.net:www     CLOSE_WAIT

    Most of the time you won't catch it when it is still connected and sending/receiving data. The deamon that accepts the connections is freshclam and it will save the new data ...

  • I use VirtualBox and had a problem with copying files between my host (main computer on which you boot your computer) and the guests (virtual computer that you run on your host).

    The fact is that it is all explained right here:

    http://www.virtualbox.org/manual/ch04.html#sharedfolders

    There are a few steps as follow.

    Install the Virtual Box Tools

    Install the Virtual Box Tools (called Guest Additions) on your guest; these tools allow your guest to communicate with the host to allow files to be written in a directory on the host.

    To install those, it should be as easy as using the ...

  • Copying an entire partition to another when both are not of the exact same size (in blocks) can be tricky, especially if that partition includes special files such as /dev/hda and FIFOs.1

    Yet, there are several ways to do so:

    • 1. Note that was the case especially in the 90's. As of today, things have come a long way and there are command line options one can use with the cp and tar instructions to copy pretty much anything. You will still have problems with some files such as locks, though. But you should not have to copy them!
  • I run a few Drupal website and once per hour I run the cron.php script. I do it only once per hour because nothing changes so often on my websites so it would require faster refreshes.

    Once in a while (relatively rarely now) I get a list of errors from CRON saying that the checks failed. The errors look something like this:

    HTTP/1.0 302 Found
    Location: /cgi-bin/ipdiags.ha
    Pragma: no-cache
    Content-Type: text/html
    
    <html><meta http-equiv=Refresh content=0;url=/cgi-bin/ipdiags.ha>
    <body></body></html>
    

    As you can see, this is a 302 so a temporary error. ...

  • How to force a download of any file in a CGI script

    I have been wondering for a while, now I have the answer, so I can share it with you guys.

    Your script has to do the following steps:

    1. Print a header which at least includes:

      1. Content-Type: application/force-download

        (you can also use octet-stream instead of force-download)

  • Well... I knew that a firewall could generate a few problems, but this one, I did not expect!

    I just could not FTP anything from my FedoraCore box. I checked the source system firewall, tweaked all sorts of options in the vsftpd.conf file to no aval.

    The error I was getting was this:

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