Frequently Asked Questions
 Question: Why do I see the following when my proftpd starts up? 

  getaddrinfo 'hostname' error: No address associated with hostname   warning: unable to determine IP address of 'hostname'

Answer: This error is ProFTPD's way of reporting that it was unsuccessful in resolving hostname to an IP address. Fixing this is a matter of configuring DNS for that hostname: properly set up an IP address for that DNS name in your DNS server, use a DNS name that has an IP address, or (as a quick fix/last resort) add that DNS name to your /etc/hosts file. The proper solution depends largely on the circumstances.

Question: If proftpd resolves any DNS names to IP addresses when it starts up, and I am using dynamic IP addresses which change after my proftpd has started, will proftpd see my new IP addresses?
Question: Unfortunately not. ProFTPD has no easy way of handling dynamic IP addresses by itself. One way of dealing with this situation is to restart proftpd periodically, which will force it to re-parse its configuration and thus re-resolve all IP addresses.

Question: What if I do not want proftpd to use DNS to resolve the hostname to an IP address because I am in an environment where there is no DNS at all?
Answer: In ProFTPD 1.3.3rc1, support for a new -S command-line option was added. This option can be used to specify the IP address of the host machine. By default, proftpd attempts to resolve the host IP address by using DNS resolution of the hostname. However, in cases where DNS is not configured for the host machine, this approach does not work.

To specify the desired IP address, use -S when starting proftpd, e.g.: 

  /usr/local/sbin/proftpd -S 1.2.3.4 ...

And if you want proftpd to listen on all interfaces, you can specify a wildcard socket using an IP address of 0.0.0.0: 

/usr/local/sbin/proftpd -S 0.0.0.0 ...

Note that will also mean that, in your proftpd.conf, any <VirtualHost> sections will need to use IP addresses, not DNS names.