White road operation and maintenance of Linux 6

1 summarizes IP address planning
in IP networks, communication nodes must have a unique IP address, the IP address of IP addressing for insulation and identifying a node; IP address is the most important subnetting.
IP address planning principles
1. recommends that each vlan assigned a class c address, mask / 24, which can accommodate 254 hosts per vlan no more than 1000 hosts, otherwise the big broadcast domain, post-security issues outstanding.
2. The principles can be summarized as: IP address of each segment can be planned route summarization simplifies route entry
3. Easy management principles: see the IP address of the user to know that this is a PC or a switch, in which area.
2, summarizes the common network management command
ping
command is a command used to test whether TCP / IP network flow or test the network connection speed is useful in determining whether the network is properly connected, and the status of the network connection.

telnet
command is used to log into the remote host, the remote host is managed.
Connectivity personal work most commonly used test port
telnet ip port
Example: the Telnet 192.168.1.195 14306
netstat
status information to the print command in Linux network system that lets you know the network of the entire Linux system
personally very popular one Related command: netstat -unltp
information basic needs can be viewed to see.

ifconfig

3, and given the IP address 167.77.88.99 mask 255.255.255.192, subnet number, what is? What broadcast address? What a valid IP address?
1. subnet number = 167.77.88.64
2. The broadcast address 167.77.88.63 =
3. ~ valid IP address 167.77.88.1 167.77.88.62 =
. 4, to add the IP address 192.168.2.2/24 eth0 NIC
IP addr the Add 192.168.2.2/24 dev eth0
. 5, Top, the iostat , vmstat command summarizes the
top: capable of running real-time monitoring system, and can be sorted by cpu, memory and execution time

vmstat: can monitor the process status of the operating system, memory, virtual memory, disk IO, context, CPU information.

iostat: Iostat is a system disk IO operations to monitor its output mainly to display statistics for read and write operations of the disk. And gives cpu usage

6, CPU usage up to find out the top 10 processes
PS -auxf | -nr the Sort -k 3 | head -10

7, crontab to achieve, within 12 months, 6 to 12 am daily point, every three hours 0 minutes to perform a / usr / bin / backup
to add a cron job
crontab -e
added:
0 6-12 /. 3 12 is usr / bin / Backup /
save and exit.