Setting Secure LDAP and Authenticating client with Secure LDAP Server

Hello boys,

follow All the post of my previous 2 blogs it will help you to setup LDAP server and authenticating client using LDAP now lets move 1 step ahead and start making our ldap server secure.

Enable SSL in OpenLDAP Server

Using encrypted sessions we can secure LDAP communication.  Transport Layer Security (TLS) is used for this purpose. Recent releases of  slapd  in Ubuntu is compiled with support for GnuTLS instead of OpenSSL, there for we need to install following packages now.

$sudo apt-get install gnutls-bin

After that we need to create certificate authority(CA) for this purpose.

#certtool --generate-privkey > /etc/ssl/private/cakey.pem

After that create a template file(/etc/ssl/ca.info) to assist the creation of self-sign CA.

cn = Example Company
ca
cert_signing_key

Now sign the generated CA.

#certtool --generate-self-signed \
--load-privkey /etc/ssl/private/cakey.pem \ 
--template /etc/ssl/ca.info \
--outfile /etc/ssl/certs/cacert.pem

Now create the key for slapd and sign it using generated CA.

#certtool --generate-privkey \
--outfile /etc/ssl/private/slapd01_key.pem

Create a template file.(/etc/ssl/slapd01.info)

organization = Example
cn = ldap01.example.com
tls_www_server
encryption_key
signing_key
expiration_days = 3650

Create a certificate and sign it with previously created CA.

#certtool --generate-certificate \
--load-privkey /etc/ssl/private/slapd01_key.pem \
--load-ca-certificate /etc/ssl/certs/cacert.pem \
--load-ca-privkey /etc/ssl/private/cakey.pem \
--template /etc/ssl/slapd01.info \
--outfile /etc/ssl/certs/slapd01.pem

Once the certificate is generated , now we need to tell LDAP about the created SSL certificate, for that we  need to create a LDIF file as below. (/etc/ssl/certinfo.ldif)

dn: cn=config
add: olcTLSCACertificateFile
olcTLSCACertificateFile: /etc/ssl/certs/cacert.pem
-
add: olcTLSCertificateFile
olcTLSCertificateFile: /etc/ssl/certs/slapd01.pem
-
add: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/ssl/private/slapd01_key.pem

Now add it to the LDAP.

$sudo ldapmodify -Y EXTERNAL -H ldapi:/// -f /etc/ssl/certinfo.ldif

Also make sure to grant read access to openldap user to each of below files and locations.

$chown openldap:openldap /etc/ssl/private/cakey.pem \
/etc/ssl/private/slapd01_key.pem  /etc/ssl/certs/cacert.pem   /etc/ssl/certs/slapd01.pem 

$chown -R openldap:openldap /etc/ssl/private 

Now enable SSL in /etc/default/slapd as below and restart the slapd daemon.(add ldaps:/// entry additionally.)

SLAPD_SERVICES="ldap:/// ldapi:/// ldaps:///"

/etc/init.d/slapd  restart

Now lets see how to access the secured LDAP server.

Configure DHCP server to access secured LDAP 

In http://mageconfig.blogspot.com/2014/10/configure-isc-dhcp-server-with-openldap.html  post I have already configured ISC DHCP to communicate with OpenLDAP server, therefor in here I will only show the extra steps required to communicate with secured OpenLDAP server.

In the DHCP server configuration file, change as below and restart the DHCP server.
/etc/dhcp/dhcpd.conf

ldap-server                 "localhost";
ldap-port 636;
ldap-ssl ldaps;
ldap-tls-reqcert never; #Telling Not to verify certificates as we have used self sign certs
ldap-base-dn                "ou=dhcp,dc=example,dc=com";
ldap-method                 static;
ldap-debug-file             "/var/log/dhcp-ldap-startup.log";
ldap-dhcp-server-cn         "server"

Configure Ubuntu Server to Authenticate with Secured LDAP

As I have explained the procedure above I will only show you the extra configurations needed. As I have used self sign certificates in here also I will disable certificate checks.

/etc/ldap.conf

.
.
uri ldaps://IpAddressOfLDAPServer:636/
.
.
ssl on
.
.

TLS_REQCERT never 
tls_checkpeer no
.
.

  
Now  on client machine I hope you have followed the previous blogs for setup ldap auth .now copy the cacaert.pem from server to client machine as it will required to validate the server certificate.

# scp /etc/ssl/certs/cacert.pem  root@<ip-address-of-client-mahine>:/etc/ssl/certs/




After that on client machine  add the below line

TLS_REQCERT allow #Which tells not to validate self sign certs




now Its a time for testing guys.




$ldapsearch -x  -H ldaps://ldap.example.com -b dc=example,dc=com

if its promts for password that means every thing is ok and now we can reconfigure the ldap-auth-config

$sudo dpkg-reconfigure ldap-auth-config

• LDAP server Uniform Resource Identifier: ldaps://LDAP-server-IP-Address
  • Change the initial string from "ldapi:///" to "ldap://" before inputing your server's information
• Distinguished name of the search base:
  • This should match the value you put in your LDAP server's /etc/phpldapadmin/config.phpfile.
  • Search for: " 'server','base',array " within the file.
  • Our example was "dc=test,dc=com"
• LDAP version to use: 3
• Make local root Database admin: Yes
• Does the LDAP database require login? No
• LDAP account for root:
  • This should also match the value in your /etc/phpldapadmin/config.php.
  • Search for: " 'login','bind_id' " within the file
  • Our example was "cn=admin,dc=test,dc=com"
• LDAP root account password: Your-LDAP-root-password

and we are done. if you are still not getting authenticated then restart the nscd service as it may happen that connection timeout has happen if its still not working then check into the 

/var/log/authlog

Thanks guys let me know if you still have any questions... 

Authenticate Client Computers Using LDAP on an Ubuntu 12/14.04

Hello Guys 

welcome back again now the final touch to our ldap server and its auth.but before that let me refer to my previous blog explaining the setup of ldap server.

I will assume that you have gone through my previous blog and setup your own LDAp server with basic config so lets move ahead

Install Client Packages

On the client machine, you will needs to install a few packages to make authentication function correctly with an LDAP server.

You can install them from the default Ubuntu repositories with the following commands:

sudo apt-get update
sudo apt-get install libpam-ldap nscd

You will be asked a variety of questions similar to the those asked when you were installing the server components.

• LDAP server Uniform Resource Identifier: ldap://LDAP-server-IP-Address
  • Change the initial string from "ldapi:///" to "ldap://" before inputing your server's information
• Distinguished name of the search base:
  • This should match the value you put in your LDAP server's /etc/phpldapadmin/config.phpfile.
  • Search for: " 'server','base',array " within the file.
  • Our example was "dc=test,dc=com"
• LDAP version to use: 3
• Make local root Database admin: Yes
• Does the LDAP database require login? No
• LDAP account for root:
  • This should also match the value in your /etc/phpldapadmin/config.php.
  • Search for: " 'login','bind_id' " within the file
  • Our example was "cn=admin,dc=test,dc=com"
• LDAP root account password: Your-LDAP-root-password

If you make a mistake and need to change a value, you can go through the menu again by issuing this command:

sudo dpkg-reconfigure ldap-auth-config

Configure Client Software

We have to adjust a few files to tell our authentication files that they can look to our LDAP server for authentication information.

First, edit the /etc/nsswitch.conf file. This will allow us to specify that the LDAP credentials should be modified when users issue authentication change commands.

sudo nano /etc/nsswitch.conf

The three lines we are interested in are the "passwd", "group", and "shadow" definitions. Modify them to look like this:

passwd:         ldap compat
group:          ldap compat
shadow:         ldap compat

Next, we will add a value to our PAM configuration.

PAM, or Pluggable Authentication Modules, is a system that connects applications that can provide authentication to applications that require authentication.

PAM is already implemented on most computers, and works behind the scenes without needing user interaction. When we installed and configured our LDAP PAM module, most of the needed information was added to the configuration files.

Edit the /etc/pam.d/common-session file:

sudo nano /etc/pam.d/common-session

Add a line to the bottom of the configuration that reads:

session required    pam_mkhomedir.so skel=/etc/skel umask=0022

This will create a home directory on the client machine when an LDAP user logs in who does not have a home directory.

We have to restart a service for these changes to be implemented:

sudo /etc/init.d/nscd restart

Permissions

During the LDAP server configuration, we created a group called "admin". This was not chosen at random. It coincides with the "admin" group that is created by default on Ubuntu machines.

The LDAP users that you added to the "admin" group will have access to the sudo command.

This is because we have a line that gives members of the "admin" group sudo access within the/etc/sudoers file. Edit the file by issuing this command:

sudo visudo

There is a line that reads:

%admin ALL=(ALL) ALL

Entries that begin with a percentage sign (%) specify a group instead of a user. If you wish to disable this functionality, or only grant specific users this functionality, comment out this line:

#%admin ALL=(ALL) ALL

Log In as an LDAP User

We have now configured our client machine enough to be able to log in as one of our LDAP users. This user does not have to exist on the client machine.

In a new terminal window (it is best to keep your original terminal window logged in, in case of a configuration mistake), ssh into the client machine using an LDAP user's credentials:

ssh LDAP_user@LDAP_client_IP_Address

You should be able to log in as if your user had been created locally. Issue the print working directory command:

pwd

You should see that the home directory you selected for your user on the LDAP server is being used on this machine. It has been created on-demand to serve the LDAP user.

If you log out and log in with a different LDAP user, you can see that there will be two home directory entries:

ls /home

user1  user2

If your user is part of the "admin" group and you didn't disable the ability in the previous section, you will have normal sudo access, otherwise, you will not.

If you issue the passwd command to change your password, you can see that it will be modifying your LDAP credentials:

passwd

Enter login(LDAP) password:

Restricting Access by Group

If you only want members of certain groups to be able to log into this specific machine, you can configure that restriction within the PAM files.

Edit the following file with root privileges:

sudo nano /etc/pam.d/common-auth

At the bottom, we will specify that PAM should look at the security access file to see how to restrict user logins. Add this to the bottom:

auth    required    pam_access.so

Save and close the file.

The file that PAM references for security information when that setting is configured is at/etc/security/access.conf. Open this file now, with root privileges:

sudo nano /etc/security/access.conf

We need to add a rule to the end of the file.

The dash (-) at the beginning of the line means this is a restriction. From the first colon (:) to the next colon, we specify who this rule applies to.

We specify that this applies to all users except root and the group "admin". Groups are given within parentheses.

From the second colon to the end of the line, we will specify under which circumstances the rule should apply. In our case, the restriction will apply in all circumstances but local logins.

-:ALL EXCEPT root (admin):ALL EXCEPT LOCAL

This will allow us to restrict logins to the "admin" group. We can add other groups or change the group.

This will also allow us to log in through the "console access" button on the DigitalOcean console if we somehow lock ourselves out of SSH.

Keep in mind that this will apply to all users, not just LDAP users. So any users you create on the client machine will need to be a member of one of the specified groups

Install and configure LDAP server on UBUNTU 14.04

Hello Guys,

I have trying to install and configure LDAP as its like Active Directory from windows   and the reason I have to configure ldap as We have more than 100+users and 100+ servers so creating a new users or adding a new server and granting access to users on that is really a hectic job.so As i googled I found LDAP  in first few like.So I will not waste your time and lets start with implementation of the same.

LDAP, or Lightweight Directory Access Protocol, is a protocol for managing related information from a centralized location through the use of a file and directory hierarchy.It functions in a similar way to a relational database in certain ways, and can be used to organize and store any kind of information. LDAP is commonly used for centralized authentication

Install LDAP

The OpenLDAP server is in Ubuntu's default repositories under the package "slapd", so we can install it easily with apt-get. We will also install some additional utilities:

sudo apt-get update
sudo apt-get install slapd ldap-utils

You will be asked to enter and confirm an administrator password for the administrator LDAP account.

Reconfigure slapd

When the installation is complete, we actually need to reconfigure the LDAP package. Type the following to bring up the package configuration tool:

sudo dpkg-reconfigure slapd

You will be asked a series of questions about how you'd like to configure the software.

• Omit OpenLDAP server configuration? No
• DNS domain name?
  • This will create the base structure of your directory path. Read the message to understand how it works.
  • There are no set rules for how to configure this. If you have an actual domain name on this server, you can use that. Otherwise, use whatever you'd like.
  • In this article, we will call it test.com 
• Organization name?
  • Again, this is up to you
  • We will use example in this guide. 
• Administrator password?
  • Use the password you configured during installation, or choose another one 
• Database backend to use? HDB
• Remove the database when slapd is purged? No
• Move old database? Yes
• Allow LDAPv2 protocol? No

Install PHPldapadmin

We will be administering LDAP through a web interface called PHPldapadmin. This is also available in Ubuntu's default repositories.

Install it with this command:

sudo apt-get install phpldapadmin

That will install all of the required web server and PHP dependencies.

Configure PHPldapadmin

We need to configure some values within the web interface configuration files before trying it out.

Open the configuration file with root privileges:

sudo nano /etc/phpldapadmin/config.php

Search for the following sections and modify them accordingly.

Change the red value to the way you will be referencing your server, either through domain name or IP address.

$servers->setValue('server','host','domain_nam_or_IP_address');

For the next part, you will need to reflect the same value you gave when asked for the DNS domain name when we reconfigured "slapd".

You will have to convert it into a format that LDAP understands by separating each domain component. Domain components are anything that is separated by a dot.

These components are then given as values to the "dc" attribute.

For instance, if your DNS domain name entry was "imaginary.lalala.com", LDAP would need to see "dc=imaginary,dc=lalala,dc=com". Edit the following entry to reflect the name you selected (ours is "test.com" as you recall):

$servers->setValue('server','base',array('dc=test,dc=com'));

The next value to modify will use the same domain components that you just set up in the last entry. Add these after the "cn=admin" in the entry below:

$servers->setValue('login','bind_id','cn=admin,dc=test,dc=com');

Search for the following section about the "hidetemplatewarning" attribute. We want to uncomment this line and set the value to "true" to avoid some annoying warnings that are unimportant.

$config->custom->appearance['hide_template_warning'] = true;

Save and close the file.

Log Into the Web Interface

You can access by going to your domain name or IP address followed by "/phpldapadmin" in your web browser:

domain_name_or_IP_address/phpldapadmin

Click on the "login" link on the left-hand side.

You will receive a login prompt. The correct Login DN (distinguished name) should be pre-populated if you configured PHPldapadmin correctly. In our case, this would be "cn=admin,dc=test,dc=com".

Enter the password you selected during our slapd configuration.

You will be presented with a rather sparse interface initially.

If you click on the "plus" next to the domain components (dc=test,dc=com), you will see the admin login we are using.

Add Organizational Units, Groups, and Users

LDAP is very flexible. You can create hierarchies and relationships in many different ways, depending on what kind of information you need accessible and what kind of use case you have.

We will create some basic structure to our information and then populate it with information.

Create Organizational Units

First, we will create some categories of information where we will place the later information. Because this is a basic setup, we will only need two categories: groups and users.

Click on the "Create new entry here" link on the left-hand side.

Here, we can see the different kinds of entries we can create.

Because we are only using this as an organizational structure, rather than an information-heavy entry, we will use the "Generic: Organizational Unit" template.

We will be asked to create a name for our organizational unit. Type "groups":

We will then need to commit the changes.

When this is complete, we can see a new entry on the left-hand side.

We will create one more organizational structure to get ourselves going. Repeat the procedure, but this time, use the name "users".

When you are done, you should have something that looks like this:

Create Groups

We will be creating three different groups that could be used to organize users into different "access" groups based on the privileges they require.

We will create an "admin" group, an "irc" group, and a "user" group. We could then allow members of different groups to authenticate if we set up client LDAP authentication.

We want to create the groups within the "groups" organizational unit. Click on the "groups" category we created. In the main pane, click on the "Create a child entry" within the groups category.

This time, we will choose the "Generic: Posix Group" category.

Fill in "admin" as the group name. Click "Create Object" and then confirm on the next page.

Repeat the process, but simply replace the "admin" name with "irc" and "user". Be sure to re-click the "ou=groups" entry before creating child entries, or else you may create entries under the wrong category.

You should now have three groups in the left-hand panel:

You can see an overview of the entries in the "ou=groups" category by clicking on that entry, and then clicking on "View 3 children":

Create Users

Next, we will create users to put in these groups. Start by clicking the "ou=users" category. Click on "Create a child entry".

We will choose "Generic: User Account" for these entries.

While adding a user you can face a tipical problem like there is no textbox for password and instate of textbox there is some error message some thing like this:

"Error trying to get a non-existant value (appearance,password_hash)"

 solution to this problem is as below:

replace password_hash with password_hash_custom which is in  /usr/share/phpldapadmin/lib/TemplateRender.php file on line no 2469  and reload the page

We will be given a lot of fields to fill out:

Fill in all of the entries with information that makes sense for your user.

Something to keep in mind is that the "Common Name" needs to be unique for each entry in a category. So you may want to use a username format instead of the default "FirstName LastName" that is auto-populated.

Click "Create Object" at the bottom and confirm on the following page.

To create additional users, we will take advantage of the ability to copy entries.

Click on the user you just created in the left-hand panel. In the main pane, click "Copy or move this entry":

Adjust the "cn=user" portion of the entry to point it to the common name you'd like to use for the new entry. Click "Copy" at the bottom:

You will be given the next page populated with your first users data. You will need to adjust it to match the new users information.

Be sure to adjust the uidNumber. Click the "Create Object" button at the bottom.

Add Users to Groups

We can add users to various groups by clicking on the group in question. In the main pane, select "Add new attribute":

Select "memberUid" from the drop down menu:

In the text field that populates, enter the first user you'd like to add. Click "Update Object" at the bottom:

You can then add more members by clicking "modify group members" and selecting them from the available choices:

I will explane how to use it in next blog which also quite easy.

Thank you guys I will appriciate your feed back if you find any error please let me know .
Enjoy.......!