Secure Webserver

You can access your personal homepage over http or https. Both protocols have the webbroot in the public_html subdirectory of your home.

Also note that local users can see what is in your public_html directory by walking through the file system. All files in a normal static html website must be readable by the webserver and so they are readable for every user who has access to the filesystem, where your home is placed. The only way to get some level of protection locally is to use a CGI in the public_html directory which is only readable and executable for you, and then use this CGI as a gateway to publish other documents also stored with permissions only readable to you. This again is no real protection for the fact that your material lies on the disk as plain files. So anybody with root access can read the files. To get around this problem the files would have to be encrypted and your CGI would have to decrypt them on the fly when delivering. This is still not really secure, but about as good as it gets with this setup.

Authentication and Authorization

While speaking about access control one must distinguish between authentication and authorization. Authentication is the process of verifying that "you are who you say you are", authorization is the process of verifying that "you are permitted to do what you are trying to do". Authorization thus requires authentication.

This approach is also implemented by Apache's htaccess configuration directives. E.g.

Website Protection

LOCAL vs. LDAP

There are two different "databases" access control can work with:

You should use LDAP if access control should be based on registered D-ITET user and groups. On the other hand, an independent access control based on self defined users (e.g. for non D-ITET user) is archived best using a LOCAL "database".

Local Password File

Follow these steps to configure access control for a sub directory within your public_html/secure directory:

  1. Create a directory, for example: mkdir ~/public_html/mySecureWebsite.

  2. Create a .htaccess file in this directory with the following content:

     AuthType Basic
     AuthName "Protected Area"
     AuthUserFile /home/<UserName>/.htpasswd
     Require valid-user
  3. Create the password file in your home-dir with the htpasswd utility:

     touch ~/.htpasswd && htpasswd -s ~/.htpasswd anyuser

    htpasswd will prompt for the new password (yes, htpasswd has a -c switch for creating a new file, but since it's pretty easy to inadvertently erase an existing file this way I recommend using the approach with touch).

  4. Test your page in the browser. If it doesn't work as expected Apache's error log (/var/log/apache2/error_log.people_ee_ssl @ people.ee.ethz.ch) might give a clue.

  5. Additional users/passwords can be added with htpasswd -s ~/.htpasswd anotheruser. Additionally, it's possible to use different password files for different subdirectories or files, for example ~/.htpasswd01 for directory ~/public_html/bla01 and ~/.htpasswd02 for directory ~/public_html/bla02 - it all depends on your needs.

  6. Read more about htaccess files here.

LDAP Directory Service

For access control against registered D-ITET users and groups a more complex htaccess file is needed based on 5 different sections. All sections together are setting up the entire htaccess file.

  1. Header
     Order deny,allow
     Deny from All 
  2. Authentication
     AuthType Basic
     AuthName "YOUR LOGIN Text"
     AuthBasicProvider ldap
  3. Anonymous LDAP Binding

    Anonymous access to the LDAP server is allowed on ITET's managed offline replica (i.e update once per day) only. Direct access to ID's LDAP Service is restricted to special proxy users. A personal proxy user for staff and proj accounts can be requested (support@ee.ethz.ch) for some special cases if anonymous access is not sufficient.

     AuthLDAPURL "ldaps://ldap02.ee.ethz.ch ldap01.ee.ethz.ch/ou=users,ou=itet,ou=auth,o=ethz,c=ch?uid?one"
  4. Authorization
    • The authorization depends on your needs. Here are some examples for common setups. Combination of authorization methods is also possible (defaults to a logical OR).
    • Primary Group
        Require ldap-attribute gidNumber=<GidNumber>
      b. Secondary Group
        AuthLDAPGroupAttribute memberUid
        AuthLDAPGroupAttributeIsDN off
        Require ldap-group cn=<GroupName>,ou=custom,ou=groups,ou=nethz,ou=id,ou=auth,o=ethz,c=ch
      c. Valid user (i.e. no further authorization, valid authentication is sufficient)
        Require valid-user
      d. List of of allowed users
        Require ldap-user <user1> <user2> 
  5. Footer
     Satisfy any

Necessary group information, i.e. group name (GID) and its corresponding number (gidNumber) can be retrieved by executing 'getent group' on an ISG.EE manged Linux client.

Read more about LDAP authentication and authorization here.

File Permissions

While using anonymous LDAP binding no special file permissions are needed A simple chmod 644 .htaccess should be fine.


CategoryWEBS

Web/Homepage/Security (last edited 2018-09-25 10:59:49 by pmeier)