. Refer also to the answer for "FTP server
says: "421 service not available, remote server has closed
If it's an FTP server on an older system, make sure that the account
exists in /etc/passwd, especially "anonymous."
This type of problem may also be caused a failure to resolve the host
addresses properly, especially if using Reverse Address Resolution
Protocol (RARP). The simple answer to this is to list all relevant
host names and IP addresses in the /etc/hosts files on each machine. (
Refer to the example /etc/hosts and /etc/resolv.conf files in:
"Sendmail Pauses for Up to a Minute at Each Command..") If the network
has an internal DNS, make sure that each host can resolve network
addresses using it.
If the host machine doesn't respond to FTP or Telnet clients at all,
then the server daemon is not installed correctly, or at all. Refer to
the manual pages: inetd and inetd.conf on older systems, or xinetd and
xinetd.conf, as well as ftpd, and telnetd.