What is the default routing command of the Linux operating system?
A: route
[root@xinsz08-1 ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
link-local * 255.255.0.0 U 1002 0 0 eth0
default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0
Remarks:
Destination: destination network or destination host. When destination is default (0.0.0.0), it means this is the default gateway.
gateway: gateway address, 0.0.0.0 means that the destination corresponding to the current record is in the same network segment as the machine, and the communication does not pass through the gateway.
genmask: The network mask of the destination field. When the destination is the host, it needs to be set to 255.255.255.255. When it is the default route, it will be set to 0.0.0.0
flags: flags
- U routing is active
- H target is a host
- G needs to go through the gateway
- R replies to entries generated by dynamic routing
- D is dynamically installed by the routing background program
- M is modified by the routing daemon
- !Reject routing
[root@xinsz08-1 ~]# ip route
192.168.1.0/24 dev eth0 proto kernel scope link src 192.168.1.18
169.254.0.0/16 dev eth0 scope link metric 1002
default via 192.168.1.1 dev eth0 proto static
https port used What is it and how to check the port number? What is the protocol of https?
HTTPS default port number is 443, https, based on HTTP protocol, provides encrypted data processing through SSL or TLS, verifies the identity of the other party and protects the integrity of data
[root@xinsz08-1 ~]# netstat -ntulp |grep 443
Remarks:
- netstat -ntlp Check the
default port numbers of all tcp ports and mysql databases. How to determine whether the mysql service is enabled on the server?
mysql port number 3306
[root@xinsz08-1 ~]# netstat -tulpn |grep 3306 View by port
[root@xinsz08-63 ~]# ps -ef |grep mysqld View by process
root 12343 9155 0 21:11 pts/0 00:00:00 grep --color=auto mysqld
Please write export LANG='en_US.UTF8' The function of this command
en_US.UTF-8: You speak English, you are in the United States, and the character set is utf-8
zh_CN. UTF-8: You speak Chinese, you are in China, and the character set is utf-8.
Please write echo 3 >/proc/sys/vm/drop_caches. What does this command do?
Release the data command occupied by the system Cache
Please write find ./type f -mtime +5 | xargs rm -rf What is the function of this command?
Find out the files 5 days ago and delete them.
Print out the contents of the /var/test.log file in real time.
tail -f /var/test.log
Please write iptables -A INPUT -p tcp --dport 8080 -j DROP this command What's the role?
-A additional rules
-j specify the processing of the package (DROP, ACCEPT, REJECT)
What are the denial of port 8080 access to the
mysql engine? Write 2 kinds of
InnoDB, MyISAM
What is the name of the service responsible for clock synchronization under Linux?
NTP
What command can be used to access a web page under linux?
links, wget
What is the command to capture all the packets arriving on the server eth0
tcpdump -n -i eth0 host IP
Please write the mask of the B segment IP address.
Class B IP address mask: 255.255.0.0
A segment 255.0.0.0
Please write out the function of lsof -i:8080 |grep log?
List processes that open port 8080 and filter log processes `What
is the command to list all virtual machines on the current server on the kvm host machine?
virsh list -all
What is the command to view all containers on the docker host server?
docker ps -a
mysql account root, password 123, database name test_db. Port 3310 host address 10.10.1.1 Please write the command to back up this database
mysql -uroot -p123 -P10.10.1.1:3306 -B test_db> test_db.
What is the command of sql.base to view mysql master-slave synchronization?
mysql -e "show slave status /G" View the status of the slave copy.
Please write out the functions of the two commands dmidecode and dmesg.
dmidecode View the hardware information under the Linux system. The
Linux dmesg command is used to display boot information.
Please write delete from user where name like “u%”; the function of this command
delete the user whose user name starts with u
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