To display a welcome or warning message for SSH users before signing in. Use issue.net file to display a massage banner. Open the following file with Notepad. 1. Create a /etc/issue.net file and fill it with the desired context 2. Change /etc/ssh/sshd_config to resemble this /etc/issue.net banner Since the publication of the Computer Misuse Act 1990, it is strongly recommended that computers display a banner before users can log in. The law stipulates that a crime of unauthorized access can only be committed if the perpetrator knew at that time that the access he was trying to obtain was not authorized. Login banners are the best way to achieve this. The Investigative Powers Regulation Act 2000 also requires that information be provided to computer users: registration banners can also be an excellent means of achieving this dissemination. When setting up a network server, it`s a good idea to add a login banner just to remind users that as a system administrator, you can monitor what they`re doing and by using the system, they agree that you can monitor them.
This will not deter a determined attacker, but will only remind users to behave themselves! In general, it`s a good idea NOT to put information in a login banner that could help a potential attacker, such as system name, output version, owner, or what the system does. By default, `/etc/issue.net` is used to store banner text that is displayed when a user connects from the network via `ssh`, `telnet` and `ftp`, etc. JANET: The UK Education and Research Network, Login Banner Policy After restarting “sshd”, users logging into the system will see a banner message when they log in. One way to view messages is to use issue.net file. issue.net: Displays a banner message before the password login prompt. By default, the telnet deamon (`telnetd`) displays the contents of `/etc/issue.net` before prompting the user for a password. Note that these escape sequences are not only translated as “agetty” and have no effect if you connect remotely, unfortunately one of the things you can`t put in the connection banner is the current network address, if you want to do this, you need to update the banner text when the network address changes! Make sure that the permissions for /etc/issue are configured. Description: If the /etc/issue file does not have the correct property, it can be edited by unauthorized users with false or misleading information.
Make sure that the permissions for /etc/issue.net are configured. linux_logon is a tool that creates ASCII art banners. The default ASCII chart is shown in the following example or created in another from a template file. It also adds system statistics such as kernel version, processor version, RAM, and usage values. By default, `/etc/issue` is used to store banner text that appears when you log in to the console locally. A legal banner contains security warnings or general information that warns the user. It can be used for security, legal information, company policies, etc. To set up a login banner for `ssh`, you need to comment on (or add) the entry that defines the banner text in the ssh deamon configuration file. When you log in to the console, you can add additional system information by using the following escape characters in the banner message: Now try to connect to the server, you will see the banner message you just added.
An area often forgotten in system protection is well-formed banner text. How you set up the login banner depends on how users log in to your system: What is a legal banner? How do I add it to /etc/issue and /etc/issue.net? The /etc/issue.net file name is the historical location of pre-connection banners for network connections with protocols such as telnet or rlogin. Some Unix providers had a version of telnetd, rshd, and/or rlogind that also used /etc/issue for network connections; Others have made it configurable, as SSHD now does. Using Lynis, I was suggested to add a legal banner. So, This Tips & Trix will cover banners for SSH and the console prompt. Add the banner message of your choice and save the file. Next, open the master SSH configuration file and enable the banners. It can be used for security, legal information, company policies, etc. One way to view messages is to use issue.net file. issue.net: Displays a banner message before the password login prompt. To display a welcome or warning message for SSH users before signing in. Reference: /etc/issue.net is displayed for users who connect from the network.
/etc/issue is displayed to local and network users unless /etc/issue.net exists and is configured. For this change to take effect, sshd must be restarted. This topic is discussed in Section 22.214.171.124 of the CentOS 5.1 Deployment Guide. “FTP Welcome Banner” If you log in to the console and contain information about the system, it is less of a security issue than if an attacker had access to the console, they can get this type of information relatively easily by simply restarting the system!. Changes to `/etc/issue` take effect immediately. One of the easiest ways to protect and secure SSH connections is to display warm-up messages for authorized Un users or welcome or information messages for authorized users.