This is Perl module Perlbal::Plugin::BackendHeaders. INSTALLATION Perlbal::Plugin::BackendHeaders installation is straightforward. If your CPAN shell is set up, you should just be able to do % cpan Perlbal::Plugin::BackendHeaders Download it, unpack it, then build it as per the usual: % perl Makefile.PL % make && make test Then install it: % make install Finally apply the modify_headers.patch to perlbal: % cat modify_headers.patch | patch -p0 Check to make sure it works: % curl -I http://mydomain.com/ HTTP/1.0 200 OK Content-Type: text/html; charset=utf-8 Content-Language: en Pragma: public X-Backend: mydomain:8880 Connection: close DOCUMENTATION Perlbal::Plugin::BackendHeaders documentation is available as in POD. So you can do: % perldoc Perlbal::Plugin::BackendHeaders to read the documentation online with your favorite pager. Victor Igumnov