compare directory trees

ssh server1 "find /usr/local/apache2/sites/htdocs/ -type f -exec basename {} \; | sort" > server1.txt; ssh server2 "find /usr/local/apache2/sites/htdocs/ -type f -exec basename {} \; | sort" > server2; comm -3 ./server1 ./server2

slowloris ddos aversion

use Nginx and openBSD/pf to protect Apache.
http://nginx.net/

here's some configuration help.
https://calomel.org/nginx.html

rpm packages by name only

rpm -qa --qf "%{NAME}\n" > hostname.rpm.txt

then you can compare to see what is missing.

comm -3 host1.rpm.txt host2.rpm.txt

Slowloris DDOS prevention

#!/bin/sh

LIMIT=100

COMMAND='netstat -n | egrep '\''tcp.*[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*:(80|443)[ ]*[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*:[0-9]*[ ]*ESTABLISHED
'\'' | awk -F'\''[ \t:]+'\'' '\''{ print $6 }'\'''

eval $COMMAND | sort | uniq -c | while read numconn ip
do
if [ $numconn -gt $LIMIT ]
then
echo "Check ASAP and renable this cron." | mail -s "IP $ip - ($numconn) went over $LIMIT connections on `hostname`" me@someemailaddress.com

sed -i 's/\(^\*.*this_script.sh*\)/#\1/g' /etc/crontab
# /sbin/iptables -I INPUT -s $ip -j DROP
fi
done