White List and Black List for SSH How to create a (username/password or certificate) white/black list for ssh? For example of blacklist, I can use any username/password combination to access the server, except the ones on the blacklist. The ssh version can be OpenSSH. And the server is a Linux. Creating lots of users on Linux for white list is not a nice way. Any approach can be used, like modifying SSH software itself, or using Linux/SSH features, or using other modules. * * * Update: Maybe I did not describe the situation clearly. Basically, I simply want any username/password combination to be able to login, except the black list. For example, if the black list is "admin/admin; root/123". I can simply use "abc/123456" to login. The server is like a VERY VULNERABLE one with almost no credential needed. For white list, I can give a number of username/password/certificate combinations for the list, not just the username.

For a blacklist, in your `sshd_config` add the `DenyUsers` entry followed by a list of users separated by a space. You can also use `DenyGroups` in a similar fashion.

For example: `DenyUsers jimmy bill joe susan`

or

`DenyGroups teachers`

A whitelist is created by using the `AllowUsers` and/or `AllowGroups` entries in the `sshd_config` file. If either of these entries is used, only those users or groups listed will be permitted to login.