10 basic examples of linux netstat command

From : http://www.binarytides.com/linux-netstat-command-examples/

1. List out all connections

$ netstat -a


2. List only TCP or UDP connections

for tcp
$ netstat -at

for udp
$ netstat -au


3. Disable reverse dns lookup for faster output

$ netstat -ant


4. List out only listening connections

$ netstat -tnl


5. Get process name/pid and user id

The process details are made available by the 'p' option.

~$ sudo netstat -nlpt


6. Print statistics

$ netstat -s

7. Display kernel routing information

$ netstat -rn


8. Print network interfaces

$ netstat -i

9. Get netstat output continuously

$ netstat -ct

10. Display multicast group information

$ netstat -g

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/