boa - a single-tasking high performance http server
] [-r chroot
Boa is a single-tasking HTTP server. That means that unlike traditional web
servers, it does not fork for each incoming connection, nor does it fork many
copies of itself to handle multiple connections. It internally multiplexes all
of the ongoing HTTP connections, and forks only for CGI programs (which must
be separate processes.) Preliminary tests show Boa is more than twice as fast
The primary design goals of Boa are speed and security. Security, in the sense
of "can't be subverted by a malicious user", not "fine grained
access control and encrypted communications". Boa is not intended as a
feature-packed server; if you want one of those, check out WN from John
Franks. Modifications to Boa that improve its speed, security, robustness, and
portability, are eagerly sought. Other features may be added if they can be
achieved without hurting the primary goals.
- instruct Boa not to fork itself (non-daemonize).
- -c server_root
- choose a server root overriding the default SERVER_ROOT #define in
The server root must hold your local copy of the configuration file
- -r chroot
- instruct Boa where to chdir and chroot to. The chdir/chroot is done before
the configuration file is read, or any log files are opened.
- boa.conf - the sole configuration file for Boa.
- The directives in this file are defined in the DIRECTIVES section.
- mime.types - the
- MimeTypes <filename> defines what Content-Type Boa will send in an
HTTP/1.0 or better transaction.
The Boa configuration file is parsed with a lex/yacc or flex/bison generated
parser. If it reports an error, the line number will be provided; it should be
easy to spot. The syntax of each of these rules is very simple, and they can
occur in any order. Where possible, these directives mimic those of NCSA httpd
1.3; We saw no reason to introduce gratuitous differences.
Note: the "ServerRoot" is not in this configuration file. It can be
compiled into the server (see defines.h
) or specified on the command
line with the -c
The following directives are contained in the boa.conf
file, and most,
but not all, are required.
- Port <integer>
- This is the port that Boa runs on. The default port for http servers is
80. If it is less than 1024, the server must be started as root.
- User <user name or UID>
- The name or UID the server should run as. For Boa to attempt this, the
server must be started as root.
- Group <group name or GID>
- The group name or GID the server should run as. For Boa to attempt this,
the server must be started as root.
- ServerAdmin <email address>
- The email address where server problems should be sent. Note: this is not
- PidFile <filename>
- Where to put the pid of the process. Comment out to write no pid file.
Note: Because Boa drops privileges at startup, and the pid file is written
by the UID/GID before doing so, Boa does not attempt removal of the pid
- ErrorLog <filename>
- The location of the error log file. If this does not start with /, it is
considered relative to the server root. Set to /dev/null if you don't want
- AccessLog <filename>
- The location of the access log file. If this does not start with /, it is
considered relative to the server root. Comment out or set to /dev/null
(less effective) to disable access logging.
- This is a logical switch and does not take any parameters. Comment out to
- CGILog <filename>
- The location of the CGI error log file. If this does not start with /, it
is considered relative to the server root. If specified, this is the file
that the stderr of CGIs is tied to, *instead* of to the ErrorLog.
- CGIumask <umask>
- The CGIumask is set immediately before execution of the CGI. The default
value is 027. The number must be interpretable unambiguously by the C
function strtol. No base is specified, so one may use a hexadecimal,
decimal, or octal number if it is prefixed accordingly.
- ServerName <server_name>
- The name of this server that should be sent back to clients if different
than that returned by gethostname.
- This is a logical switch and does not take any parameters. Comment out to
disable. Given DocumentRoot /var/www, requests on interface 'A' or IP
'IP-A' become /var/www/IP-A. Example: http://localhost/ becomes
- VHostRoot <directory>
- The root location for all virtually hosted data Comment out to disable.
Incompatible with 'Virtualhost' and 'DocumentRoot'!! Given VHostRoot
/var/www, requests to host foo.bar.com, where foo.bar.com is ip a.b.c.d,
become /var/www/a.b.c.d/foo.bar.com Hostnames are "cleaned", and
must conform to the rules specified in rfc1034, which are be summarized
Hostnames must start with a letter, end with a letter or digit, and have as
interior characters only letters, digits, and hyphen. Hostnames must not
exceed 63 characters in length.
- DefaultVHost <hostname>
- Define this in order to have a default hostname when the client does not
specify one, if using VirtualHostName. If not specified, the word
"default" will be used for compatibility with older
- DocumentRoot <directory>
- The root directory of the HTML documents. If this does not start with /,
it is considered relative to the server root.
- UserDir <directory>
- The name of the directory which is appended onto a user's home directory
if a ~user request is received.
- DirectoryIndex <filename>
- Name of the file to use as a pre-written HTML directory index. Please make
and use these files. On the fly creation of directory indexes can be
- DirectoryMaker <directory>
- Name of the program used to generate on-the-fly directory listings. The
program must take one or two command-line arguments, the first being the
directory to index (absolute), and the second, which is optional, contains
what Boa would have the "title" of the document be. Comment out
if you don't want on the fly directory listings. If this does not start
with /, it is considered relative to the server root.
- KeepAliveMax <integer>
- Number of KeepAlive requests to allow per connection. Comment out, or set
to 0 to disable keepalive processing.
- KeepAliveTimeout <integer>
- Number of seconds to wait before keepalive connections time out.
- MimeTypes <file>
- The location of the mime.types file. If this does not start with /,
it is considered relative to the server root. Set to /dev/null if you do
not want to load a mime types file. Do *not* comment out (better use
- DefaultType <mime type>
- MIME type used if the file extension is unknown, or there is no file
- AddType <mime type> <extension> [extension...]
- Associates a MIME type with an extension or extensions.
- Redirect, Alias, and ScriptAlias <path1> <path2>
- Redirect, Alias, and ScriptAlias all have the same semantics -- they match
the beginning of a request and take appropriate action. Use Redirect for
other servers, Alias for the same server, and ScriptAlias to enable
directories for script execution.
Redirect allows you to tell clients about documents which used to exist in
your server's namespace, but do not anymore. This allows you tell the
clients where to look for the relocated document.
Alias aliases one path to another. Of course, symbolic links in the file
system work fine too.
ScriptAlias maps a virtual path to a directory for serving scripts.
Please see the included boa.conf
for defaults and examples.
Like the Linux kernel, even numbered versions are "stable", and odd
numbered versions are "unstable", or rather,
"development". Versions 0.91 and 0.91beta of Boa were released by
Paul Phillips <firstname.lastname@example.org>
Version 0.92 was released by Larry Doolittle on December 12, 1996.
Version 0.93 was the development version of 0.94.
Version 0.94 was released 22 Jan 2000.
There are probably bugs, but we are not aware of any at this time.
Boa was created by Paul Phillips <email@example.com>. It is now being
maintained and enhanced by Larry Doolittle <firstname.lastname@example.org> and Jon
Linux is the development platform at the moment, other OS's are known to work.
If you'd like to contribute to this effort, contact Larry or Jon via e-mail.
This program is distributed under the GNU General Public License, as noted in
each source file.