|  |  | A bastion host is a secure server that is exposed to the outside world. All unnecessary services are turned off, and only minimum services are left running. The bastion host is configured only for a network's necessary accounts, and may be configured as an FTP server, Web server, DNS server, or email server. Consistent and thorough backups are essential, because we can expect the exposed server to be attacked. The bastion host should be monitored closely, and often for possible compromise attempts.