Category: Blog

It should be very simple to set up an FTP server on a Linux server but for some reason I always seem to have an issue with it. The first question is which daemon to install when there are so many. The main three contenders seem to be pure-ftpd, proftpd and vsftpd but even choosing between them can be daunting.

Many (if not all) FTP servers seem to have been written with the intent to either providing FTP access for people with shell accounts on the FTP server or for anonymous users. I have no interest in anonymous access and the only one with local account that need file access is myself and I much prefer to use scp via Cyberduck instead. So my requirement for a pure virtual FTP server is usually not mainstream and I invariably find myself lost in all configuration descriptions.

Here is a simple step for setting up pure-ftpd on a Debian system and add an account:

• Install the server [apt-get install pure-ftpd]
• Create an FTP group [groupadd ftp]
• Create an FTP user [useradd -g ftp -d /dev/null -s /etc ftp]
• Create a folder to hold the FTP data [mkdir /var/ftp]
• Change owner on the folder [chown ftp:ftp /var/ftp]
• Add a pure-ftpd user [pure-pw useradd testuser -u ftp -d /var/ftp -N 300]
• Save the changes [pure-pw mkdb]
• Run the server [/usr/sbin/pure-ftpd -j -lpuredb:/etc/pure-ftpd/pureftpd.pdb &]

To start the server automatically, use xinetd and add the following to /etc/xinetd.d/ftp:

service ftp
{
socket_type = stream
server = /usr/sbin/pure-ftpd
server_args = -j -lpuredb:/etc/pure-ftpd/pureftpd.pdb
protocol = tcp
user = root
wait = no
disable = no
}


Then restart xinetd (/etc/init.d/xinetd restart).

Ping is no doubt one of the world’s most wide-spread applications. It is even so common that most people that use it probably don’t even know that they don’t actually “ping” the remote host. What they do is to send ICMP Echo requests and wait from replies.

Despite being great for what it does the standard GNU ping utility (or the Windows application for that matter) fails to record the time when the ping was sent and the output is in some quasi readable format that is not trivial to import into some application.

This Perl script wraps the Linux/UNIX form of the ping utility to output the sequence number and the round trip time as comma separated values. It also prepends each line with the current date and time so that the output can be imported into a spreadsheet to create a graph of the round trip time over time.

N.B. This perl script will not work on Windows since the output format differs from that on Linux/UNIX.

Attachments

• tping.pl.gz

As I wrote earlier, I have bought myself an ALIX 2c0, a smallish embedded computer. It is designed and manufactured by PC Engines and has the following specification:

• 433MHz AMD Geode CPU
• 128MB RAM
• Compact flash slot for storage
• 2 mini-PCI slots for WiFi or other uses
• One serial port that is uses as console but can be reconfigured (although limited in functionality

There are number of distributions that could be used on this system. I found Voyage Linux to be the most interesting since it includes the standard Debian package manager. This means that it is effortless to install additional applications.

To get Voyage Linux onto the ALIX I did this (using another computer running Linux):

1. Download Voyage Linux 0.5.0 or later from the Voyage Linux web site
2. Untar the archive [ tar –numeric-owner -jxvf voyage-0.5.0.tar.bz2 ]
3. Change directory [ cd voyage-0.5.0 ]
4. Create a directory where the compact flash disk can be mounted [ mkdir /mnt/voyage ]
5. Insert the compact flash disk and check which device name it gets (N.B. be absolutely certain that you get this correct or you may end up wiping your hard drive) – This instruction assumes that the compact flash disk is /dev/sda
6. Run the script [usr/local/sbin/format-cf.sh /dev/sda] within the downloaded and unzipped archive. This will initialise the compact flash disk – Again, please verify which device name corresponds to the compact flash disk on your system
7. Run the script [usr/local/sbin/voyage.update]

The script will go through the installation and ask questions. Most of the options will be correct so it is mostly a matter of pressing enter a number of times. What you will want to change is the following:

• The target profile should be set to “4 – ALIX” instead of “7 – WRAP” which is the default
• The target disk should be set to whatever device is your compact flash disk (e.g. /dev/sda) – PLEASE check the correct device name on your system or risk wiping your hard drive, but on the other hand if you didn’t heed my warning earlier your disk is already toast.
• The drive where the compact flash disk should be mounted should be set to the folder created above (e.g. /mnt/voyage)

At the end you will be faced with a summary of all the settings. Check that it is correct and then type “y” to continue. The copying will take a minute or two, after that the compact flash disk is ready. Just place it in the ALIX, connect it to your network and boot.

The system will automatically use DHCP to get an IP address. It can be reached by SSH with the default root password of “voyage”.