サーバ公開時にapacheのバージョンを非表示にした方が、既知の脆弱性を突かれる可能性が
減るので取り敢えずやっておきましょう。
# nano /etc/apache2/conf.d/security
#
# Disable access to the entire file system except for the directories that
# are explicitly allowed later.
#
# This currently breaks the configurations that come with some web application
# Debian packages. It will be made the default for the release after lenny.
#
#<Directory />
# AllowOverride None
# Order Deny,Allow
# Deny from all
#</Directory>
# Changing the following options will not really affect the security of the
# server, but might make attacks slightly more difficult in some cases.
#
# ServerTokens
# This directive configures what you return as the Server HTTP response
# Header. The default is 'Full' which sends information about the OS-Type
# and compiled in modules.
# Set to one of: Full | OS | Minimal | Minor | Major | Prod
# where Full conveys the most information, and Prod the least.
#
#ServerTokens Minimal
#ServerTokens OS
#ServerTokens Full
ServerTokens Prod <-- これでバージョン情報は消えます
#
# Optionally add a line containing the server version and virtual host
# name to server-generated pages (internal error documents, FTP directory
# listings, mod_status and mod_info output etc., but not CGI generated
# documents or custom error documents).
# Set to "EMail" to also include a mailto: link to the ServerAdmin.
# Set to one of: On | Off | EMail
#
ServerSignature Off
#ServerSignature On
#
# Allow TRACE method
#
# Set to "extended" to also reflect the request body (only for testing and
# diagnostic purposes).
#
# Set to one of: On | Off | extended
#
TraceEnable Off
#TraceEnable On