Shulou(Shulou.com)06/03 Report--

Gateway address, broadcast address, assigneable IP address range of Linux network and process 100.0.16tick 28 corresponding network segment: default is maximum Ip address 100.0.254 broadcast address: 100.0.0.255 assignable IP address range: 100.0.0.241-254 learn the use of tcpdump

Tcptump: a packet analysis tool for intercepting packets on the network-I ens33 specifies the network card. By default, the local card-tnn does not display a timestamp, and displays-c packet capture times with ip and port. Omitting or not writing will continue-v to display details.

(1) check all the packages of the network card:

Tcmdump-tnn-I ens33tcpdump-tnn-c 10-I ens33

(2) production supervision target: host or network.

Tcpdump-I ens33 host 192.168.136.4tcpdump-I ens33 net 192.168

(3) Direction control: src source, dst destination followed by host or network

Tcpdump-I ens33 dst 192.168.136.4 and tcp port 22tcpdump-I ens33 src 192.168.136.1 tcpdump-I ens33 src 192.168.136.1 and dst 192.168.136.4

(4) Agreement, which has no keywords, and is followed directly by the protocol type. If omitted, tcp,udp,icmp,arp means all protocols.

Tcpdmup-I ens33 tcptcpdmup-I ens33 src 192.168.136.1 tcptcpdump-I ens33 icmp or tcp and src 192.168.136.4

(5) Port port

Tcpdump-I ens33 icmp or tcp and src 192.168.136.4tcpdmup-I ens33 src 192.168.136.1 and tcp port 80 describes in detail the causes and hazards of the zombie process

Zombie process: in UNIX-like systems, a zombie process is a process that completes execution (caused by a fatal error or receiving a termination signal at run time through an exit system call) but still has an entry (process control block PCB) in the operating system's schedule, which is in a "terminated state". Zombie processes will consume system resources, and if there are many, it will seriously affect the performance of the server Explain the meaning of vmstat output result in detail: [root@localhost ~] # vmstatprocs-memory- swap---io-----system---cpu-r b swpd free buff cache si so bi bo in cs us sy id wa st1 0 69152 371148 0 0 119 7 59 67 0 99 0 0

(1) procs:

R: number of processes waiting to run; queue length of tasks waiting to run on CPU

B: number of processes in uninterruptible sleep; length of blocked task queue

(2) memory:

Swpd: total swap memory usage

Free: total amount of physical memory free

Buffer: total amount of memory used for buffer

Cache: total amount of memory used for cache

(3) swap:

Si: the data rate at which data enters the swap (kb/s)

So: the rate at which data leaves the swap (kb/s)

(4) io:

Bi: the speed at which data is read from the block device to the system (kb/s)

Bo: rate at which data is saved to block devices (kb/s)

(5) system:

In:interrupts, interrupt rate

Cs:context switch, the rate of context switching

(6) cpu:

Us: user space

Sy:system

Id:idle

Wa:wait

St: stolen

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