ServerSignature Off
ServerTokens Prod

The first setting above will obviously turn the server signature off which is displayed at the bottom of the server generated pages – like error pages or directory listings.  The second setting will limit the HTTP response header to just include “Apache” as opposed to “Apache/2.2.0″.  There is a similar setting in lighttpd:

server.tag = "lighttpd"

This will make the same “Server:” response header be whatever that variable is set to, in this case just “lighttpd” which again just removes the software version.

Along these lines is hiding that PHP actually exists on your system.  To do this changing “expose_php” within your php.ini to Off will remove any header response that you are actually running PHP.

# Proxy 350z.ws back to apache
$HTTP["host"] =~ "www.3(5|7)0z.ws" {
        $HTTP["url"] !~ "(wp-content|wp-includes|css|js|php$|^/blog/$)" {
                proxy.server = ( "/" =>
                        ( "localhost" =>
                                ( "host" => "127.0.0.1", "port" => 81 )
                        )
                )
        }
}

Note one (obvious) draw back is that you have to run Apache as well, but since I’m stopping most hits at Lighttpd by serving everything in wp-content, wp-includes, anything with css, js or php in the name, I can greatly reduce the number of Apaches I start and maintain. In my case my Apache prefork config looks like this:

<IfModule mpm_prefork_module>
    StartServers          3
    MinSpareServers       2
    MaxSpareServers       5
    MaxClients          15
    MaxRequestsPerChild   10
</IfModule>

You’ll also notice I’m not proxying the folder where WordPress lives back either, this is because it contains no rewrites for it specifically and will get the majority of the hits.

The Graph definition is as follows:

[lighttpd]
TITLE lighttpd Requests/Second
YAXIS # reqs/sec
DEF:RPS=lighttpd.rrd:reqpersec:AVERAGE
LINE2:RPS#0000CC:reqs/sec
COMMENT:
GPRINT:RPS:LAST:Requests per Second   : %5.1lf (cur)
GPRINT:RPS:MAX: : %5.1lf (max)
GPRINT:RPS:MIN: : %5.1lf (min)
GPRINT:RPS:AVERAGE: : %5.1lf (avg)

The Xymon scripts source code is:

#!/usr/bin/perl -w
#############################################################################
# $Id: mi-lighttpd.pl 21 2009-05-07 19:22:28Z rar $
#############################################################################

use strict;
use File::Slurp;
use LWP::Simple;
use Data::Dumper;

my $port = 80;
my $bbtest = 'lighttpd';

#############################################################################
## BB and related test constants
#############################################################################

use constant CLEAR  => 'clear';
use constant GREEN =>  'green';
use constant YELLOW => 'yellow';
use constant RED    => 'red';
use constant PURPLE => 'purple';

{

#############################################################################
## Setup Variables
#############################################################################
	my $DATA    = "";
	my $color   = GREEN;
	my $status  = $bbtest . " OK";
	my $previous_run;
	my $current_run;
	my $restarted   = 0;
	my @delta_tests = ( 'total_kbytes', 'total_accesses', 'uptime' );
	my @counter_tests   = ( 'total_accesses', 'total_kbytes', 'uptime', 'reqpersec' );
	my @write_log;
	my $backup_log    = "$ENV{BBTMP}/$ENV{MACHINE}.lighttpd.data";
	my %lighttpd_states = (
		'_' => 'awaiting_conn',
		'.' => 'connect',
		'r' => 'reading_req',
		'R' => 'reading_req_post',
		's' => 'sending_reply',
		'S' => 'sending_reply_end',
		'q' => 'request_start',
		'Q' => 'request_end',
		'W' => 'write',
		'h' => 'handle_request',
		'C' => 'close',
		'E' => 'hard_error',
	);
	my %error_states = (
		'reqpersec' => '100',
		'sending_reply' => '100'
	);

	my %warn_states = (
		'reqpersec' => '75',
		'sending_reply' => '75'
	);

#############################################################################
## Gather previous run data & current data
#############################################################################

	# Get Last Status
	if ( -e $backup_log ) {

		#Split Apart Data
		my @data = read_file($backup_log);
		if (@data) {
			foreach my $line (@data) {
				chomp($line);
				my ( $key, $value ) = split( /=/, $line, 2 );
				$previous_run->{$key} = $value;
			}
		}
		else {
			$previous_run = 0;
		}
	}

	my $status_data = get "http://localhost:$port/server-status?auto";

#############################################################################
## Munge the data up to get what we want
#############################################################################

	if ( defined($status_data) ) {

		my @data = split( /n/, $status_data );
		foreach my $line (@data) {
			chomp($line);
			my ( $key, $value ) = split( /: /, $line );
			$key =~ s/ /_/g;
			$key = lc($key);
			$current_run->{$key} = $value;
		}

		# Create array of new values to save for our next run
		foreach ( keys %{$current_run} ) {
			push @write_log, "$_=$current_run->{$_}n";
		}

		# Calculate Incremental Data
		if ($previous_run) {
			# We need to check if we restarted here to avoid negitives
			if ($current_run->{uptime} > $previous_run->{uptime} ){
				foreach (@delta_tests) {
						$current_run->{$_} = $current_run->{$_} - $previous_run->{$_};
				}
			}
			else {
				$status = $bbtest . " Restarted";
				$color = YELLOW;
				$restarted = 1;
			}
		}

		# Break out scoreboard data
		foreach ( keys %lighttpd_states ) {
			$current_run->{ $lighttpd_states{$_} } = 0;
		}
		foreach ( split( //, $current_run->{scoreboard} ) ) {
			$current_run->{ $lighttpd_states{$_} }++;
		}

		if ( !$restarted ) {
			# Get Req/Sec since last check
			$current_run->{reqpersec} = sprintf "%.2F", ( $current_run->{total_accesses} / $current_run->{uptime} ) if $current_run->{uptime};

			## save our counter tests for the next run incase we
			## lighttpd gets restarted we have some non-zero data to send in
			foreach (@counter_tests) {
				push @write_log, "cur_$_=$current_run->{$_}n";
			}    

			# Check for warning states
			foreach ( keys %warn_states ) {
				if ( $current_run->{$_} > $warn_states{$_} ) {
					$color  = YELLOW;
					$status = $bbtest . " $_ > $warn_states{$_}";
				}
			}

			# Check for error states
			foreach ( keys %error_states ) {
				if ( $current_run->{$_} > $error_states{$_} ) {
					$color  = RED;
					$status = $bbtest . " $_ > $error_states{$_}";
				}
			}
		}
		else {
			## So we restarted, and we don't want to send nothing
			## and we don't want to send negitives on calculated tests
			## since we saved them last run for this purpose, we'll send in
			## our last run stats to keep from having huge drops in the
			## graphs.
			foreach (@counter_tests) {
				$current_run->{$_} = sprintf "%.2F", $previous_run->{ "cur_".$_ };
			}
		}

		# Delete Some Unwanted Data
		delete $current_run->{scoreboard};
		delete $current_run->{uptime};

		# Create Hobbit Data
		foreach ( sort keys %{$current_run} ) {
			$DATA .= "$_:$current_run->{$_}n";
		}

		# Actually Write last run file
		write_file( $backup_log, @write_log );

	}
	else {
		$status = $bbtest . " unable to get server-status";
		$color  = CLEAR;
	}

#############################################################################
## Give data to hobbit
#############################################################################

	# hobbit formatted output
	my $report_date = `/bin/date`;
	chomp($report_date);

	## DEV DEBUG
	#print "$ENV{BB} $ENV{BBDISP} 'status apollo,xipnet,net.$bbtest $color $report_date - $statusnn$DATA'n";
	system("$ENV{BB} $ENV{BBDISP} 'status apollo,xipnet,net.$bbtest $color $report_date - $statusnn$DATA'n");
}