Buscar

48.2.6. Securing FTP

download PDF
The File Transfer Protocol (FTP) is an older TCP protocol designed to transfer files over a network. Because all transactions with the server, including user authentication, are unencrypted, it is considered an insecure protocol and should be carefully configured.
Red Hat Enterprise Linux provides three FTP servers.
  • gssftpd — A Kerberos-aware xinetd-based FTP daemon that does not transmit authentication information over the network.
  • Red Hat Content Accelerator (tux) — A kernel-space Web server with FTP capabilities.
  • vsftpd — A standalone, security oriented implementation of the FTP service.
The following security guidelines are for setting up the vsftpd FTP service.

48.2.6.1. FTP Greeting Banner

Before submitting a username and password, all users are presented with a greeting banner. By default, this banner includes version information useful to crackers trying to identify weaknesses in a system.
To change the greeting banner for vsftpd, add the following directive to the /etc/vsftpd/vsftpd.conf file:
ftpd_banner=<insert_greeting_here>
Replace <insert_greeting_here> in the above directive with the text of the greeting message.
For mutli-line banners, it is best to use a banner file. To simplify management of multiple banners, place all banners in a new directory called /etc/banners/. The banner file for FTP connections in this example is /etc/banners/ftp.msg. Below is an example of what such a file may look like:
######### # Hello, all activity on ftp.example.com is logged. #########

Note

It is not necessary to begin each line of the file with 220 as specified in Section 48.2.1.1.1, “TCP Wrappers and Connection Banners”.
To reference this greeting banner file for vsftpd, add the following directive to the /etc/vsftpd/vsftpd.conf file:
banner_file=/etc/banners/ftp.msg

Important

Make sure that you specify the path to the banner file correctly in /etc/vsftpd/vsftpd.conf, or else every attempt to connect to vsftpd will result in the connection being closed immediately and a 500 OOPS: cannot open banner <path_to_banner_file> error message.
Note that the banner_file directive in /etc/vsftpd/vfsftpd.conf takes precedence over any ftpd_banner directives in the configuration file: if banner_file is specified, then ftpd_banner is ignored.
It also is possible to send additional banners to incoming connections using TCP Wrappers as described in Section 48.2.1.1.1, “TCP Wrappers and Connection Banners”.
Red Hat logoGithubRedditYoutubeTwitter

Aprender

Pruebe, compre y venda

Comunidades

Acerca de la documentación de Red Hat

Ayudamos a los usuarios de Red Hat a innovar y alcanzar sus objetivos con nuestros productos y servicios con contenido en el que pueden confiar.

Hacer que el código abierto sea más inclusivo

Red Hat se compromete a reemplazar el lenguaje problemático en nuestro código, documentación y propiedades web. Para más detalles, consulte el Blog de Red Hat.

Acerca de Red Hat

Ofrecemos soluciones reforzadas que facilitan a las empresas trabajar en plataformas y entornos, desde el centro de datos central hasta el perímetro de la red.

© 2024 Red Hat, Inc.