VSFTPD - limit the number of simultaneous connections for a single IP address

By default VSFTPD allows unlimited connection from the same client IP address.

1: Open vsftpd.conf file

Use text editor such as vi to edit /etc/vsftpd.conf or /etc/vsftpd/vsftpd.conf file:
# vi vsftpd.conf

2: Setup limitation

Set up the max_per_ip=4 (this will limit simultaneous connection to 4 number only)
max_per_ip=4

3: Restart vsftpd

# /etc/init.d/vsftpd restart 

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Get Hostname from IP address

To get the hostname from the IP address.
The simplest way is to use the “host” utility provided by Gnu/Linux. Just run…

poison:~ # host 64.233.187.99
99.187.233.64.in-addr.arpa domain name pointer jc-in-f99.google.com.
poison:~ #

This will query the name server and provide you with the hostname of the IP address.By default it will query the nameserver listed in the /etc/resolv.conf file.

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Quick configuration of NFS

NFS Consists of the following:

/etc/exports –> /etc/exports contains all the NFS shares

/usr/sbin/exportfs -r
#exportfs -r is used to synchronize nfsd in memory with the /etc/exports file
#Use exportfs -v to see which shares nfsd is currently exporting

/etc/rc.d/init.d/nfslock - which has 2 parts
/sbin/rpc.lockd
/sbin/rpc.statd

/etc/rc.d/init.d/nfs - which has 3 parts
/usr/sbin/rpc.rquotad
/usr/sbin/rpc.mountd
/usr/sbin/rpc.nfsd

At bare minimum you need to have portmap (or portmapper), mountd (or rpc.mountd), and nfsd (or rpc.nfsd) running; otherwise NFS isn’t running.

#Sample nfs /etc/exports file:
/home/ftp/pub (ro,insecure,all_squash)
/home/ftp/pub adminsvr(rw,insecure,all_squash)

#Above we have two entries, one for everyone, and one
for the adminsvr machine.

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How To disable telnet service

Login as root to your server:

Edit /etc/xinetd.d/telnet
# vi /etc/xinetd.d/telnet

Search for: "disable = no"
Change it to: disable = yes

Save and Exit

Restart xinted
# /etc/rc.d/init.d/xinetd restart

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How to disable CTRL-ALT-DEL from rebooting a Linux system

The action taken for CTRL-ALT-DEL is defined in /etc/inittab and if we will look in that file we will see a line similar to the one from bellow :

ca::ctrlaltdel:/sbin/shutdown -t3 -r now

If we want to disable this action we only have to change this line. 

We can delete it, comment it, or even replace it with something like:

ca:12345:ctrlaltdel:/bin/echo "CTRL-ALT-DEL is disabled"

After making any changes to the inittab file, 

you will have to tell init to reload it, in order to activate the changes. 

To do that, simply run as root:

init q

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To maximize your ipad battery life

• Try to keep your ipad away from the direct sunlight.
• Turn on Bluetooth only when it is needed and turn off after using it.
• Screen brightness should be reduced.
• Just disable or reduce the system sounds.
• Try to use WI-Fi network where possible instead of 3G.
• Disable “vibration” while playing games.
• You must discharge your ipad battery fully at least once in a month.
• Set your ipad settings for your screen to be locked quickly.

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Allow normal user to mount cdrom

By default, this device is not accessible by all of your users. To allow users to mount the CDROM drive, login as root and execute the following command

# chmod a+r /dev/cdrom

This will allow any user on your Linux system to mount the CDROM drive from their console or desktop.

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