Starting sshd:PRNG is not seeded

You might have received this error when restarting SSHD.

#/etc/rc.d/init.d/sshd restart

Stopping sshd: [ OK ]

Starting sshd:PRNG is not seeded

[FAILED]

Here is the fix.

cd /dev/

./MAKEDEV generic

Now try starting SSH.

List of TCP and UDP Port Numbers

The port numbers are divided into three ranges: the Well Known Ports,the Registered Ports, and the Dynamic and/or Private Ports.

The Well Known Ports are those from 0 through 1023.

The Registered Ports are those from 1024 through 49151

The Dynamic and/or Private Ports are those from 49152 through 65535

http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers

Anonymous FTP Access

Anonymous FTP access (especially anonymous FTP uploads) can be a big security risk, so your web host may not permit you to turn this feature on. If anonymous FTP access is turned off on your web server, accessing any of cPanel's anonymous FTP options won't affect anything. You should contact your web host if you want to know if they support anonymous FTP access.

To turn anonymous FTP access on or off, you should click Setup Anonymous FTP Access from the FTP Manager screen in cPanel. You will be presented with two simple checkboxes. The first allows you to offer anonymous (public) FTP access to ftp.domain.com (only the public_ftp directory). The next checkbox allows anonymous (public) FTP upload access to your ftp.domain.com/public_ftp/incoming/ directory. Both of these items should be unchecked for security reasons unless you are certain you want to offer anonymous FTP access.

If you want people logging in via anonymous FTP to see a custom message from you when they log into your server, then write it here. This will only get displayed if the FTP client the person is using displays messages from the server. Some web browsers will display this message when accessing your account via FTP, but many people turn off viewing such messages especially if they are using a dedicated FTP program. In most cases, if the message is not displayed on screen, it is still written to the user's FTP transcript (log).

How to Flush DNS Cache

1) For Windows

To flush or remove DNS cache:
C:>ipconfig /flushdns

To see the DNS cache:
C:>ipconfig /displaydns

Do this if you want to see the syntax;
C:>ipconfig /?

2) For Linux

- To restart the nscd daemon, type /etc/rc.d/init.d/nscd restart in your terminal
- Once you run the command your linux DNS cache will flush.

3) For Mac OS X

- type lookupd -flushcache in your terminal to flush the DNS resolver cache.
ex: bash-2.05a$ lookupd -flushcache
- Once you run the command your DNS cache (in Mac OS X) will flush.

Thanks
Nobs

How to disable ping in Linux servers

Add the line

net.ipv4.conf.icmp_echo_ignore_all = 1
in /etc/sysclt.conf

To re-enable ping
echo 0 > /proc/sys/net/ipv4/icmp_echo_ignore_all

Or add the line

net.ipv4.conf.icmp_echo_ignore_all = 0
in /etc/sysclt.conf

Alternatively, we can use IPtables to disable ping

# iptables -A INPUT -p icmp -j DROP

Command to list all directories greater than 1 GB

This command will list all the directories greater than 1GB

# du -h ./ | grep ^[0-9.]*G

Kernel Compilation

Steps to do Kernel Compilation

------------------------------------------

cd /usr/src
wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.17.11.tar.bz2
tar -xjvf linux-2.6.17.11.tar.bz2
copy your current config over
do uname -r to see what kernel your running and copy it, example:
cp /boot/config-2.6.9-22.0.2.EL .config
make menuconfig
make bzImage
make modules
make modules_install
make install