Apache documentation

Apache HTTP Server: Compatibility Notes with NCSA's Server

Apache HTTP Server Version 1.3

Compatibility Notes with NCSA's Server

While Apache is for the most part a drop-in replacement for NCSA's httpd, there are a couple gotcha's to watch out for. These are mostly due to the fact that the parser for config and access control files was rewritten from scratch, so certain liberties the earlier servers took may not be available here. These are all easily fixable. If you know of other non-fatal problems that belong here, let us know.

Please also check the known client problems page.

The basic mod_auth AuthGroupFile-specified group file format allows commas between user names - Apache does not.
If you follow the NCSA guidelines for setting up access restrictions based on client domain, you may well have added entries for, AuthType, AuthName, AuthUserFile or AuthGroupFile. None of these are needed (or appropriate) for restricting access based on client domain. When Apache sees AuthType it (reasonably) assumes you are using some authorization type based on username and password. Please remove AuthType, it's unnecessary even for NCSA.
OldScriptAlias is no longer supported.
exec cgi="" produces reasonable malformed header responses when used to invoke non-CGI scripts.
The NCSA code ignores the missing header. (bad idea)
Solution: write CGI to the CGI spec or use exec cmd="" instead.
We might add virtual support to exec cmd to make up for this difference.
Icons for FancyIndexing broken - well, no, they're not broken, we've just upgraded the icons from flat .xbm files to pretty and much smaller .gif files, courtesy of Kevin Hughes at EIT. If you are using the same srm.conf from an old distribution, make sure you add the new AddIcon, AddIconByType, and DefaultIcon directives.
Apache versions before 1.2b1 will ignore the last line of configuration files if the last line does not have a trailing newline. This affects configuration files (httpd.conf, access.conf and srm.conf), and htpasswd and htgroup files.
Apache does not permit commas delimiting the methods in <Limit>.
Apache's <VirtualHost> treats all addresses as "optional" (i.e. the server should continue booting if it can't resolve the address). Whereas in NCSA the default is to fail booting unless an added optional keyword is included.
Apache does not implement OnDeny use ErrorDocument instead.
Apache (as of 1.3) always performs the equivalent of HostnameLookups minimal. minimal is not an option to HostnameLookups.
To embed spaces in directive arguments NCSA used a backslash before the space. Apache treats backslashes as normal characters. To embed spaces surround the argument with double-quotes instead.
Apache does not implement the NCSA referer directive. See PR#968 for a few brief suggestions on alternative ways to implement the same thing under Apache.
Apache does not allow ServerRoot settings inside a VirtualHost container. There is only one global ServerRoot in Apache; any desired changes in paths for virtual hosts need to be made with the explicit directives, eg. DocumentRoot, TransferLog, etc.

More to come when we notice them....

Apache HTTP Server Version 1.3

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