ifconfig command is used to view the current network configuration for ethernet cards and
iwconfig displays the network configuration for wireless cards.
[[email protected] ~]$ ifconfig enp2s0f1: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 ether d8:c4:97:41:27:de txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 38 bytes 4503 (4.3 KiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 38 bytes 4503 (4.3 KiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 virbr0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255 ether 52:54:00:55:6e:ed txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 wlp3s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.43.182 netmask 255.255.255.0 broadcast 192.168.43.255 inet6 2409:4072:610a:f3b:cb9c:bd9f:ff6e:a23c prefixlen 64 scopeid 0x0 inet6 fe80::9a9d:5958:dbf1:6836 prefixlen 64 scopeid 0x20 ether 98:22:ef:b4:70:e7 txqueuelen 1000 (Ethernet) RX packets 265050 bytes 335273482 (319.7 MiB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 109678 bytes 16079690 (15.3 MiB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 [[email protected] ~]$
iwconfig can be used to make temporary changes in the network interfaces.
Running any kind of application/command/game and so on, creates something that is called process. The process runs with the privileges with the user who created it, this way the process is controlled and limited to run only under certain capabilities. The user who creates a process is the owner if it and it can not be controlled by other users with same or lower privileges. In our case, if the sysadmin user runs a process, another user with same or lower privilege level, can not control it but it can be controlled by the root user. The
ps command is used to view the processes.
The default output for
ps command includes 4 columns and displays only the processes for the current terminal:
PID: process identifier, is a unique ID used to identify each process and to control it;
TTY: terminal name where the process is running, is used to identify a process if there are more that have same name;
TIME: total amount of processor time used by the process;
CMD: command that started the process;
To view the processes from the entire system
ps -e command must be executed and
ps -f displays more details for each process. The two commands above can be combined into one:
Updating the passwords in Linux
passwd command is used to change the password. The users can only change their own password and the root user can change the password of any user.
passwd [OPTIONS] [USER]
passwd command is used without arguments, the terminal automatically starts the procedure for changing the password for current user.
If you want to see the details about the status of the password you must follow the following steps:
[[email protected] ~]$ sudo -i [sudo] password for sulthan: [[email protected] ~]# passwd -S sulthan sulthan PS 2020-08-08 0 99999 7 -1 (Password set, SHA512 crypt.) [[email protected] ~]#
1st column: username – sulthan
2nd column: password status – P = usable password; L = locked password; NP = no password;
3rd column: date – when the password was last change
4th column: minimum – the minimum number of days until the user can change the password
5th column: maximum – the maximum number of days until the password will expire
6th column: warn – the number of days before the password will expire and the user will be warned
7th column: inactive – the number of days after the password will expire and the user will remain active
8th column: info – details about the password status and encryption