Install Parallels Tools on CentOS for share folders

Source: http://tp69.wordpress.com/2012/10/03/parallels-tools-centos-server/
Issue: CentOS doesn't automatically mount it by default.
Solution: Mount it manually. Make sure your network connection is good in advance.

mount -r -t iso9660 /dev/sr0 /mnt/
cd /mnt
./install


Once done, restart the CentOS and the share folders will be automatically mounted on /media/psf

Move file for Mac OS

1. Command + C 

2. Option + Command + V

nf_conntrack: table full, dropping packet.

Could be DoS/DDoS attack

echo 102400 > /proc/sys/net/netfilter/nf_conntrack_max
echo 120 > /proc/sys/net/netfilter/nf_conntrack_generic_timeout
echo 54000 > /proc/sys/net/netfilter/nf_conntrack_tcp_timeout_established
echo 30 > /proc/sys/net/netfilter/nf_conntrack_tcp_timeout_time_wait
sysctl -p

Login to remote server with private key

1. Generate private/public keys
   ssh-keygen -t rsa

2. Upload the public key (id_rsa.pub) to remote server
   scp ~/.ssh/id_rsa.pub howard@remoteServer:~/.ssh/
   or
   cat ~/.ssh/id_rsa.pub | ssh howard@remoteServer "cat >> ~/.ssh/authorized_keys" 

3. Login to remote server and append the key
   ssh howard@remoteServer
   mkdir .ssh
   chmod 700 .ssh
   cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
   chmod 600 ~/.ssh/authorized_keys
   rm -rf id_rsa.pub

4. It's done!



To convert RSA private key to pem file, run the command below:
openssl rsa -in ~/.ssh/id_rsa -outform pem > id_rsa.pem

NIC checksum offload enable/disable

To enable/disable NIC checksum offload:

[Windows]
   . Go to Control panel -> Network and Internet -> Network and Sharing Center
   . Click "Change adapter settings"
   . Right click on the NIC and select "Properties"
   . Click "Configure" -> Advanced tab
   . You will find
        . UDP Checksum Offload (IPv4)
        . TCP Checksum Offload (IPv4)
        . IPv4 Checksum Offload
   . Enable/disable could be done there.

Wireshark filter data in payload

. To filter packets with hex value "0xff 0x13" in payload

  frame contains ff:13

Change console resolution for CentOS permanently

vi /etc/grub.conf

append "vga=791" without the quotes to the kernel line

vi/vim settings

/etc/virc for vi
/etc/vimrc for vim
~/.vimrc

syntax on
set autoindent

set number

set sw=4
set tabstop=4
set cindent

Linux mount NAS with NFS type

showmount -e IPAddress

sudo mount -t nfs IPAddress:/ShareFolder /MountPoint

Convert Big5 and UTF-8

convmv: http://www.j3e.de/linux/convmv/

convmv -f big5 -t utf-8 -r --notest folder

-f: from
-t: to
-r: recursive
--notest: do it. If not added, it only tests it

MOOC (Massive Open Online Course)

UdaCity (Programming)
   https://www.udacity.com/

Coursera (Engineering)
   https://www.coursera.org/

Code Cademy (Programming)
   http://www.codecademy.com/

Academic room
   http://www.academicroom.com/

edX
   https://www.edx.org/

Khan Academy (Everything)
   https://www.khanacademy.org/

Code.org (For Children)

均一教育平台
   http://www.junyiacademy.org/