IDC server administrator must have LINUX knowledge

One, password cracking

1. Generally we use single-user mode into the system. We are used to crack the system password. Because sometimes customers forget their passwords or machines are hacked.

When starting linux, press E in the grub option menu to enter the edit mode to edit the kernel line plus /init 1 (or /single), such as
kernel /boot/vmlinuz-2.4.18-14 Ro root=LABEL=/press E
Add single
in front of ro ​​kernel /boot/vmlinuz-2.4.18-14 single ro root=LABEL=/
Enter, press B to reboot system. Re-password:
root@#passwd root (set the root password)
Enter new unix password: enter the new password
root@init 6 reboot the system (this is generally like the REDFLAG version of the LINUX operating system Crack method)

2.debian linux system password cracking

First in the grub option menu 'Debian GNU/Linux,...(recovery mode)', press e to enter edit mode
Then, edit the ro single at the end of the kernel line and change it to rw single init=/bin/bash, press b to restart
and then enter the following command
root@(none)#mount -a
root@(none)#passwd root
root@(none)#reboot

3.RedHat/CentOS/Fedora System Password Cracking

First, press E in the grub option menu. Edit mode
Then edit the kernel line and add S (or Single)
Then press B, start to single-user mode
Then enter the following command
# mount -t proc proc /Proc
# mount -o remount,rw /
#passwd
#s Sync
#reboot

4.Freebsd system password cracking

Step 1 Boot into the boot menu
Next select each item (press 4) to enter single user mode
After entering, enter a list of commands
root@#mount -a
root@#fsck -y
root@#passwd(change password command)
root@#root(user name to crack password )
Enter new unix password:
root@#init 6 (restart)

5.Solaris system password cracking

First select solaris failasfe item in the grub option menu
Then the system prompts Do you wish to have mounted read-write on /a ?[y,n,?] Select y
Next enter single user mode
Then enter the following command: passwd can be restarted
root@#init 6 (restart)

6.SUSE system password cracking

is also the first step to restart the machine, after the grub boot interface appears, start linux Add init=/bin/bash to the option, and pass the init=/bin/bash parameter to the kernel to make the OS run the login program. Before running the bash, a command line.
Then wait a moment (none) #: command line.
At this time, enter mount -n /-o remount, rw means to remount the root file system to read and write. After the read and write permissions, you can change the password through the passwd command.
At this time, you can reset the password by entering the passwd command.
Remember to use mount -n /-o remount after the modification is complete, and set the root file system to the original state.

The above knowledge includes almost all the password cracking methods of the Linux system version, hoping to help everyone in the work.

Second, extract the file

tar.bz 2 file decompression #tar jxvf *.tar.bz 2
tar.gz file decompression #tar xzpf *.tar.gz< BR> rpm file decompression #rpm -ivh *.rpm
Generally, these files are decompressed, and other files are decompressed in a small way, which can also be found on the Internet. I won't go into details here.

Third, the LINUX open ssh service

this service, but IDC room LINUX necessary in the matter, because you want to remotely manage servers, then we will generally adopt the service of. So the first thing we have to ensure after installing the system is that this service can run normally. Of course, there are different ways to open different versions of Linux. Here is a comprehensive introduction:
1.Debian
Installation: apt-get install openssh-server Restart after installation
Service: /etc/init.d/ssh restart
2.Ubuntu
Installation: sudo apt-get install openssh-server Restart after installation
Start the service: sudo /etc/init.d/ssh restart
3.freebsd
Install the default installation, just restart: /etc/rc.d/sshd restart
4.redhat
rpm -ivh openssh-3.5p1-6
rpm -ivh oeenssh-server-3.5p1-6
Start sshd service /etc/Rc.d/init.d/sshd start

IV. Turn off the firewall

Generally, after we install the machine for the customer, in order to avoid the situation that the firewall that comes with LINUX can not be remote, we are all Turn off the firewall. Generally on the following two ways:

1) take effect after the restart
open: chkconfig iptables on
closed: chkconfig iptables off
2) with immediate effect, after the restart failure
on: Service iptables start
Close: service iptables stop
There is another case to enter this command: /etc/rc.d/init.d/iptables stop Different Linux version commands are different.
It should be noted that for other services under Linux, you can use the above commands to perform the opening and closing operations.
When the firewall is turned on, do the following settings, open the relevant port,
modify the /etc/sysconfig/iptables file, add the following:
-A RH-Firewall-1-INPUT -m state —— State NEW -m tcp -p tcp -dport80 -j ACCEPT
-A RH-Firewall-1-INPUT -m state -state NEW -m tcp -p tcp -dport22 -j ACCEPT

V. Set the NIC IP address

Check the NIC IP ifconfig
or enter the /etc/sysconfig/network-scrips/directory
cat ifcfg-eth0
Modify the network configuration in FreeBSD: # Ee /etc/rc.conf
FC4 NIC IP modification #vi /etc/sysconfig/network-scripts/ifcfg-eth0
Configuration files are these:
Default gateway configuration file: /etc/sysconfig /network
NIC IP configuration file: /etc /sysconfig /network-scripts /ifcfg-eth0 which after etho configuration corresponds to the name of
card need to restart the card service network restart

for everyone Summarize some small knowledge commands and talk about it here first. Next time I use more skills and knowledge to write out for you, I hope everyone can learn LINUX help. Thank you.