Use SRP to establish a Secure Linux Telnet Server (2) (1)

8) the PAM Authentication Module provides authentication information to applications through the PAM library.
9) after the authentication is completed, the application has two options:
Grant the required permissions to the user and notify the user.
The authentication fails and the user is notified.
The PAM workflow is shown in Figure 1.

Figure 1 PAM Workflow
PAM usage:

#cd /usr/src/redhat/SOURCES/srp-2.1.1/base/pam_eps.#install -m 644 pam_eps_auth.so pam_eps_passwd.so /lib/security

The above command installs the PAM module in the/lib/security directory. Run the "/usr/local/bin/tconf" command to create the/etc/tpasswd and/etc/tpasswd. conf files.
2. Use the eps pam module for password verification
1) first back up the/etc/pam. d/system-auth file
2) modify the/etc/pam. d/system-auth file in the following format:

auth required /lib/security/pam_unix.so likeauthnullok md5 shadowauth sufficient /lib/security/pam_eps_auth.soauth required /lib/security/pam_deny.soaccount sufficient /lib/security/pam_unix.soaccount required /lib/security/pam_deny.sopassword required /lib/security/pam_cracklib.so retry=3password required /lib/security/pam_eps_passwd.sopassword sufficient /lib/security/pam_unix.sonullok use_authtok md5 shadowpassword required /lib/security/pam_deny.sosession required /lib/security/pam_limits.sosession required /lib/security/pam_unix.so

Note that the first line in bold indicates that the PAM eps_auth module can meet the authentication requirements. The second line in bold indicates that the pam_eps_passwd.so module of PAM is used for password management.
3) convert the standard password to the EPS format
4) The pam_eps_passwd.so module of the/etc/pam. d/system-auth configuration file writes the password verification string of the EPS version to the/etc/tpasswd file. Modify the/etc/pam. dpasswd file in the following format:

auth required /lib/security/pam_stack.soservice=system-authaccount required /lib/security/pam_stack.soservice=system-authpassword required /lib/security/pam_stack.soservice=system-auth