[nando99]

well, i've increased the limit to 256, updated to the latest version of php and disabled php-suhosin... i'm also using mod-security with the default configuration plus this additional code for ddos prevention.. thoughts?

SecRuleEngine On

SecAuditEngine RelevantOnly
SecAuditLogType Serial
SecAuditLog logs/mod_security.log

# a folder where mod_security will store data variables
SecDataDir logs/mod_security-data

# ignore requests from localhost or some other IP
SecRule REMOTE_ADDR "^127\.0\.0\.1$" "phase:1,nolog,allow"

# for all non static urls count requests per second per ip
# (increase var requests by one, expires in 1 second)
SecRule REQUEST_BASENAME "!(\.avi$|\.bmp$|\.css$|\.doc$|\.flv$|\.gif$|\
                            \.htm$|\.html$|\.ico$|\.jpg$|\.js$|\.mp3$|\
                            \.mpeg$|\.pdf$|\.png$|\.pps$|\.ppt$|\.swf$|\
                            \.txt$|\.wmv$|\.xls$|\.xml$|\.zip$)"\
                            "phase:1,nolog,pass,initcol:ip=%{REMOTE_ADDR},setvar:ip.requests=+1,expirevar:ip.requests=1"

# if there where more than 5 requests per second for this IP
# set var block to 1 (expires in 5 seconds) and increase var blocks by one (expires in an hour)
SecRule ip:requests "@eq 5" "phase:1,pass,nolog,setvar:ip.block=1,expirevar:ip.block=5,setvar:ip.blocks=+1,expirevar:ip.blocks=3600"

# if user was blocked more than 5 times (var blocks>5), log and return http 403
SecRule ip:blocks "@ge 5" "phase:1,deny,log,logdata:'req/sec: %{ip.requests}, blocks: %{ip.blocks}',status:403"

# if user is blocked (var block=1), log and return http 403
SecRule ip:block "@eq 1" "phase:1,deny,log,logdata:'req/sec: %{ip.requests}, blocks: %{ip.blocks}',status:403"

# 403 is some static page or message
ErrorDocument 403 "<center><h2>Go away..."