Monthly Archives: March 2008

Ubuntu Server 7.10: Installing Proftpd and ‘warning: unable to determine IP address of’

I had some trouble installing proftpd today on a VPS server. For anyone that hasn’t used linode, it’s a colo service that lets people lease different grades of Linux VPS servers at reasonable prices. I’ve been using them for 4 months with few problems.

Installing proftpd in Ubuntu is easy. All you have to do is open a Terminal window or SSH into your server and type:

sudo apt-get install proftpd

However for some reason, the Ubuntu distros mounted on Linode’s servers have a quirk or two that require a few tweaks to get the server working. The first thing is whether to run the server in standalone or xinetd mode. The server won’t be able access port 21 unless it’s operating in standalone mode. So, set it to standalone mode.

The second quirk, which is not unique to Linode VPS servers, regards resolving the host’s address. You must add the server’s static address to the hosts file. For example, if your machine’s name is ‘johnny’ and the static IP address is

To edit your hosts file type

sudo vi /etc/hosts

Your hosts file  should look like this:       localhost johnny

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

You can determine your machine’s host name by opening the file,¬† ‘/etc/hostname’.

Aftewards, check your proftpd configuration. To do this, type:

sudo proftpd -td5

If you would like more information on setting up Proftpd or Ubuntu’s network configuration. Please consult the following: