주식회사 누리아이티

1. Preparation before installing BaroPAM

In order to use the PAM module, the PAM package must be installed by default. To verify installation, execute the following command. If it is not installed, you can install Redhat and CentOS with "yum install *pam*" and other commands "sudo apt-get install pam".

In order to access information assets and use the PAM module, the OpenSSH (Open Secure Shell) package must be installed to provide reliable and safe ssh and sftp services. To verify installation, execute the following command. If it is not installed, you can install Redhat and CentOS with "yum install *openssh*" and "yum install *openssl*" and "sudo apt-get install openssl" commands.

In the case of Redhat and CentOS, "Selinux" stands for "Security Enhanced Linux" and provides a better security policy than basic Linux. If it is activated because it is too good, it is blocked by a security problem and BaroPAM does not work (Failed to open tmp secret file "/usr/baropam/.baro_auth~" [Permission denied]). So, most of them are disabled (SELINUX=enforcing → disabled).

It is not applied immediately and is applied only after rebooting.

If you want to apply the changed contents to the currently connected terminal without rebooting, run the following command.

To download and install the BaroPAM authentication module, connect to the root account and create a directory (/usr/baropam) to download and install the module as follows.

Grant the directory permissions (read, write, execute) for downloading and installing BaroPAM modules as follows.

2. BaroPAM installation module download

The BaroPAM authentication module connects with the root account, then moves to the directory for downloading and installing the module (/usr/baropam) and downloading the module as follows.

When the download of the BaroPAM authentication module is completed, the method to decompress the tar file is as follows.

When the BaroPAM authentication module is uncompressed, the following BaroPAM related modules are created in the baropam directory.

3. BaroPAM configuration file creation

The BaroPAM configuration file must be created by executing the baro_auth program. It should be located under /usr/baropam, the directory of the BaroPAM authentication module.

형식)

The contents of the setting options of the BaroPAM configuration file are as follows.

Note) The filename of the -s option is the file name including the directory where the BaroPAM configuration file is created (the file access authority is 444), and if the hostname of the set server is not correct, BaroPAM may not operate normally. If the hostname is changed, it must be reflected in the relevant item of environment setting.

Example of use)

If you set up each BaroPAM configuration file for each account, connect to the account and proceed with the work. (Not root)

1) Your emergency scratch codes are :

Emergency scratch code is a super authentication key that can be used to access the SSH server again in case it is lost when the BaroPAM app, a one-time authentication key generator, cannot be used, so it is better to write it down somewhere.

2) Enter "y" for all of the following questions.

 even prevent man-in-the-middle attacks (y/n) y

   Do you want to disallow multiple uses of the same authentication key? y

 Will the one-time authentication key timeout be set to 30 seconds? y

The contents set in .baro_auth, the BaroPAM configuration file, are as follows.

The contents of the setting items of .baro_auth, the BaroPAM configuration file, are as follows.

4. BaroPAM configuration

To set the BaroPAM module, input the setting method in the sshd file at the top as follows.

For reference, the secret parameter is the name of the BaroPAM configuration file, and encrypt is the encryption/decryption flag (yes or no) for the BaroPAM configuration file.

If each BaroPAM configuration file is set for each account, input the setting method in the sshd file to set the BaroPAM module at the top as follows.

* "nullok" means that 2nd authentication (one-time authentication) is omitted for accounts where BaroPAM is not set.

For programs that cannot be "interactive process" like filezilla, you have to use the forward_pass option in PAM to enter the password and one-time authentication key together when entering the password. In this case, the openssh client, Windows Remote Desktop Protocol (RDP), VMWare Horizon, and filezilla all have to enter this input.

When entering a one-time authentication key such as a password in the password input window (Password & verification code:) using forward_pass, enter the password first and then enter the one-time authentication key without spaces. For example, if the password is "baropam" and the one-time authentication key is "123456", you can enter "baropam123456".

If you use forward_pass, you can enable 2-factor authentication for most services that require authentication.

If you add the BaroPAM module to the top of the /etc/pam.d/su file, the 2nd authentication key (one-time authentication key) input can be applied even when the general account attempts to elevate privileges to "root" with the "su" command. So the security is further improved.

In the case of Desktop Linux, if you want to use BaroPAM on the GUI login screen, enter the setting method in the maximum amount as follows.

Example) For Debian, Ubuntu, SUSE, and fedora Linux

After gdm-password and gdm-autologin are configured, it is necessary to restart gdm-password or gdm-autologin after checking whether the PAM module is properly added.

Then, a screen for entering "Verification code", a one-time authentication key of BaroPAM, appears on the login screen as follows.

Example) HamoniKR OS, Cloud OS, Mint Linux

After configuring lightdm and lightdm-autologin, it is necessary to restart lightdm or loghtdm-autologin after checking whether the PAM module is properly added.

Then, a screen for entering "Verification code", the one-time authentication key of BaroPAM, appears on the login screen as follows.

Example) In case of TmaxOS

After glogin configuration is finished, it is necessary to restart glogin after checking whether the PAM module is properly added.

Then, a screen for entering "Verification code", the one-time authentication key of BaroPAM, appears on the login screen as follows.

Among the contents of the "/etc/ssh/sshd_config" file, which is a configuration file for configuring the sshd daemon, the following parameters need to be changed.

After sshd configuration is finished, it is necessary to restart SSH Server after checking whether the PAM module is properly added.

Ubuntu, Debian or Linux Mint, Fedora:

In the case of Ubuntu and Mint, if the connection is not possible after restarting ssh, it is a problem of firewall configuration. Therefore, you must disable the firewall configuration and restart it using the following command.

CentOS or RHEL:

When using the BaroPAM module, if you need to exclude from the ACL for accounts to be excluded from 2nd authentication, create an ACL file in the directory set when setting up the BaroPAM environment, and then enter the account to be excluded as follows. (The file access permission for .baro_acl must be set to 444.)

If the time of the information asset is different from the current time, the one-time authentication key does not match and the one-time authentication key does not match. Therefore, to initialize the time to the same time, set the time in crontab as follows and restart crontab.

If the time of the information asset is different from the current time, the one-time authentication key does not match and the one-time authentication key does not match. Therefore, if the time zone (Timezone) is not set when the server is installed, the computer clock is displayed in PST, US Pacific time. (During summer time, PDT.) In other words, it appears in California time. This should be changed to KST, the Korean standard time, as follows.

Recently, it is possible to set the system time as the current time in the root account using NTP (Network Time Protocol) as a method of time synchronization (time server time synchronization) for information assets.

In order to use NTP, the NTP package must be installed by default. To verify installation, execute the following command. If it is not installed, you can install Redhat, CentOS 8 or lower version with "yum install ntp" and other "sudo apt-get install ntp" commands.

Registering the ntpd service in the startup program when booting the server and checking whether ntp is activated can be checked with the following command.

Checking whether the ntpd daemon is activated when booting the server using chkconfig If level 3 or 5 is off (off), it is not automatically activated. In order to activate automatically, you must change 3 and 5 to on (active) with the following command.

NTP servers operating in Korea are as follows.

Configure the NTP server operating in Korea in "/etc/ntp.conf", a configuration file for configuring the ntpd daemon, as follows.

The iburst option is a type of option setting that shortens the time it takes to synchronize.

After the configuration for the ntpd daemon configuration is completed, it is necessary to restart the NTP daemon after checking whether the NTP configuration is properly added.

You can check the ntpd time with the following command.

* The indicated ip is the ntp server fetching the current time.

In order to use NTP, the NTP package must be installed by default. To verify installation, execute the following command. If it is not installed, you can install Redhat, CentOS 8 or later version with "yum install chrony" command.

NTP servers operating in Korea are as follows.

Configure the NTP server running in Korea in "/etc/chrony.conf", a configuration file for configuring the ntpd daemon, as follows.

After the configuration for the ntpd daemon configuration is completed, it is necessary to restart the NTP daemon after checking whether the NTP configuration is properly added. (Register to start the chrony service and start it at boot time)

You can check the ntpd time with the following command.

Server list to receive time / Server list registered in chrony.conf file)

Server information to get time)

Check information such as time status and synchronization)

If the PAM configuration file is incorrectly configured or the file is damaged, users may not be able to log in. The sulogin command does not use PAM, so you may need the root password to boot the system in single-user mode and fix problems.

There are several reasons for booting in single-user mode:

1) When fsck checks or cleans filesystems other than / and /usr

2) When you forget the administrator (root) password

3) When the /etc/fstab file is incorrectly modified and the booting fails

4) When other critical files are incorrectly set and returned.

To boot in single user mode (administrator), at the boot prompt, follow the steps below.

boot: linux single

If the system is in operation, it is as follows.

 # telinit 1

After recovery, you need to switch to multi-user mode.

# telinit 3 or

# telinit 5 or

# shutdown -r now

5. How to connect to Linux

When connecting with Putty, you just need to do the same as the normal connection process, but there is one thing to set. In the environment setting, select attempt "Keyboard-Interactive" auth(SSH-2) in "connection -> SSH -> auth" and connect to SSH.

Putty Download and Documentation related materials can be found at the following URL.

For putty)

When prompted to enter the "Verification code", enter the one-time authentication key generated by the BaroPAM app.

If authentication is successful, you can enter the SSH login password as follows.

For Mobile SSH)

When prompted to enter the "Verification code", enter the one-time authentication key generated by the BaroPAM app.

If authentication is successful, you can enter the Mobile SSH login password as follows.

For FileZilla)

When connecting to FileZilla, it is different from the normal connection process. Select "File(F) -> Site Manager(S)" from the top left menu and select "SFTP-SSH File Transfer Protocol" in the "Protocol(t):" item on the General tab screen. Select "Interactive" in the "and "Logon type (L):" items, and click the "Connect (C)" button as follows.

Then, the password input screen appears as follows. On the password input screen, check the content of "Try:", enter the one-time authentication key generated by the smartphone into the "Password (P):" input field, and click the "OK (O)" button.

Then, the password input screen appears as follows. In the password input screen, check the contents of "Try:", enter the password for the login account in the "Password (P):" input field, and click the "OK (O)" button to access the server.

For SFTP)

When prompted to enter the "Verification code", enter the one-time authentication key generated by the BaroPAM app.

If authentication is successful, you can enter the SFTP login password as follows.

SecureFX Download and Documentation related materials can be found at the following URL.

In conclusion, 2nd authentication can be an effective means of protecting password authentication by adding an additional layer of protection, and regardless of whether it is used or not, it is up to the user's choice, but the adoption of 2nd authentication is an industry trend.

If an error such as Apr 18 12:01:10 localhost sshd[2280]: pam_succeed_if(sshd:auth): requirement "uid >= 1000" not met by user "root" occurs, go to "/etc/pamd/system-auth". If the configured uid is greater than or equal to 1000, authentication is to be performed. If the uid is greater than or equal to 500, you can change the value to perform authentication and restart sshd.

6. BaroPAM environment removal

When BaroPAM is installed and the BaroPAM module is not used, the method to remove the contents set in the sshd file can be commented out or deleted as follows.

Among the contents of the "/etc/ssh/sshd_config" file configured in the sshd daemon, the following parameters must be changed.

After sshd configuration is finished, it is necessary to restart SSH Server after confirming that the PAM module has been properly removed.

Ubuntu, Debian or Linux Mint:

Fedora:

CentOS or RHEL: