How to find only files with specified last modified date?

To find all files in the current directory that have been modified since yesterday (24 hours ago) use:

find . -maxdepth 1 -mtime -1

How to set apache and mysql to run at server reboot

sudo chkconfig httpd on

sudo chkconfig mysqld on 

How to check if apache, mysql is configured to start at server reboot

chkconfig --list httpd
chkconfig --list mysqld

iptables

Add a rule
sudo iptables -A INPUT -p tcp -m state --state NEW,RELATED,ESTABLISHED -m tcp --dport 1234 -j ACCEPT 

Insert a rule to a specific line
sudo iptables -I INPUT 7 -p tcp -m state --state NEW,RELATED,ESTABLISHED -m tcp --dport 1234 -j ACCEPT

The above example inserts the rule before the line 7. If no line number is defined it will use the default value of 1 in which your rule is inserted at the topmost line. 

Delete a rule
-D INPUT -p tcp -m state --state NEW,RELATED,ESTABLISHED -m tcp --dport 1234 -j ACCEPT 

Saving rules
service iptables save

Restart service
service iptables restart