13 Linux Network Configuration and Troubleshooting Commands

This link will review the following command for network configuration and troubleshooting.

1. ifconfig 
2. ping
3. traceroute
4. netstat 
5. dig
6. nslookup
7. route
8. host
9. arp 
10. ethtool
11. iwconfig
12. hostname 
13. system-config-network

http://www.tecmint.com/linux-network-configuration-and-troubleshooting-commands/

Handy howto for ubuntu

Most common task for admin was document here server-world.info. I found this accidentally. It include installation of OS, as well as common package such as ssh, dns, dhcp, virtualization, database and proxy. This is a good place to start.

http://server-world.info/en/note?os=Ubuntu_10.04

18 Tar Command Examples in Linux

Command tar is widely used in Linux. This command help admin back up file in compressed format. If you are new to Linux, this is a must for you. 

http://www.tecmint.com/18-tar-command-examples-in-linux/

Tunning nginx worker process

From stackoverflow here : http://stackoverflow.com/questions/7325211/tuning-nginx-worker-process-to-obtain-100k-hits-per-min

worker_processes  4;  # 2*number of cpus
events {
    worker_connections  19000;  #it's the key to high performance - have a lot of coinnections available
}
worker_rlimit_nofile    20000;  #each connection needs a filehandle (or 2 if you are proxying)
keepalive_timeout  5;  #that' another key - close live connections as early as possible or disable them completely
#total amount of users you can serve in 1 second = worker_processes*worker_connections/keepalive_timeout

More info about nginx directive: http://blog.martinfjordvald.com/2011/04/optimizing-nginx-for-high-traffic-loads/

Java JRE for ubuntu, Debian, Mint

Since the java are under the oracle control, some license policy changed. Linux distro are also move away from original java(sun/oracle) to openjdk. I found this link that help you install java whether openjdk or oracle java.

https://sites.google.com/site/easylinuxtipsproject/java

[link] Nginx "how to" - Fast and Secure Web Server

I found useful link describe nginx configuration. For newbie, this could be a starting guide for nginx. There are examples config for various common nginx usage  : static files, ssl, reverse proxy. And some explanation of directives are also provided.

Let's have a look ! https://calomel.org/nginx.html

ssh with out password

Are you boring with entering password every times logging in to linux via ssh? The followings are time saving and secure without storing user password in clear text.

HOST_SRC = Your system.
HOST_DEST = The system you want to login.

1. On HOST_SRC
-generating key (/.ssh/id_rsa.pub) when you are prompted to enter pass pharse just press enter.
$ssh-keygen -t rsa


-transfer id_rsa.pub to HOST_DEST use scp.
$scp ~/.ssh/id_rsa.pub username@ip:/home/username/
(this will be the last time you enter password :) ) 


2. On HOST_DEST 

$ cat id_rsa.pub >>~/.ssh/authorized_keys
$ chmod 700 ~/.ssh/authorized_keys






refer: https://blogs.oracle.com/jkini/entry/how_to_scp_scp_and