Configuring Dog Tag (PKI) Certificate Authority on Fedora

After trialling several web based CA's Dog Tag was one of the few CA's I found a reasonable amount of documentation for and has readily available packages for CentOS / Fedora.

Firstly let's install the package (it's not currently available in the stable repo yet):

sudo yum --enablerepo=updates-testing install dogtag-pki 389-ds-base

We will use 389 Directory Server to create a new LDAP server instance that Dogtag can use:

sudo setup-ds.pl --silent\
 General.FullMachineName=`hostname`\
 General.SuiteSpotUserID=nobody\
 General.SuiteSpotGroup=nobody\
 slapd.ServerPort=389\
 slapd.ServerIdentifier=pki-tomcat\
 slapd.Suffix=dc=example,dc=com\
 slapd.RootDN="cn=Directory Manager"\
 slapd.RootDNPwd=yourpassword

and then create our CA subsystem with:

sudo su -
pkispawn

Subsystem (CA/KRA/OCSP/TKS/TPS) [CA]: 

Tomcat:
  Instance [pki-tomcat]: 
  HTTP port [8080]: 
  Secure HTTP port [8443]: 
  AJP port [8009]: 
  Management port [8005]: 

Administrator:
  Username [caadmin]: 
  Password: 
  Verify password: 
  Import certificate (Yes/No) [N]? 
  Export certificate to [/root/.dogtag/pki-tomcat/ca_admin.cert]: 

Directory Server:
  Hostname [YOURVM.LOCAL]: 
  Use a secure LDAPS connection (Yes/No/Quit) [N]? 
  LDAP Port [389]: 
  Bind DN [cn=Directory Manager]: 
  Password: 
  Base DN [o=pki-tomcat-CA]: 

Security Domain:
  Name [LOCAL Security Domain]: 

Begin installation (Yes/No/Quit)? Y

Log file: /var/log/pki/pki-ca-spawn.20171108144208.log
Installing CA into /var/lib/pki/pki-tomcat.
Storing deployment configuration into /etc/sysconfig/pki/tomcat/pki-tomcat/ca/deployment.cfg.
Notice: Trust flag u is set automatically if the private key is present.
Created symlink /etc/systemd/system/multi-user.target.wants/pki-tomcatd.target → /usr/lib/systemd/system/pki-tomcatd.target.

    ==========================================================================
                                INSTALLATION SUMMARY
    ==========================================================================

      Administrator's username:             caadmin
      Administrator's PKCS #12 file:
            /root/.dogtag/pki-tomcat/ca_admin_cert.p12

      To check the status of the subsystem:
            systemctl status [email protected]

      To restart the subsystem:
            systemctl restart [email protected]

      The URL for the subsystem is:
            https://YOURVM.LOCAL:8443/ca

      PKI instances will be enabled upon system boot

    ==========================================================================

We can now either use the CLI or web-based interface to manage the server - however we will firstly need to ensure that the certificate we generated prior (/root/.dogtag/pki-tomcat/ca_admin.cert) is included in the Firefox certificate store:

Firefox >> Edit >> Preferences >> Advanced >> Certificates >> View Certificates >> 'Your Certificates' >> 'Import...'

Browse to the web ui: https://YOURVM.LOCAL:8443/ca

You should be presented with a certificate dialog like below:

End users can access the following URL in order to request certificates:

https://yourvm.local:8443/ca/ee/ca/

For this purposes of this tutorial we will keep things simple and generate a certificate for use on a Windows machine - so let's firstly select 'Manual Server Certificate Enrolment':

openssl genrsa -out computer.key 2048

openssl req -new -sha256 -key computer.key -out computer.csr

cat computer.csr

and paste the certificate in as below:

Hopefully then (after hitting submit) we'll see:

Now - let's head to the admin section and approve the request:

https://yourvm.local:8443/ca/agent/ca/

List Requests >> Find

Click on the request, check the details etc. and finally hit 'Approve' at the bottom.

Once it has been approved you should see a copy of the (BASE64 encoded) certificate at the bottom of the confirmation page.

Finally we'll want to package this up a long with the corresponding private key:

openssl pkcs12 -inkey computer.key -in computer.pem -export -out computer.pfx

(where 'computer.pem' is the public portion that has just been generated.)

Proceed by importing the PFX file into the Windows Computer certificate store under 'Personal'.

Sources

Fedora Project :: PKI :: Quick Start

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Implementing 802.1X with a Cisco 2960, FreeRADIUS and Windows 7 / 10

802.1X: 802.1X allows you to securely authenticate devices connecting to a network - while often employed in wireless networks it is also often used along side wired ones as well. A typical transaction will involve the authenticator (the switch in this case) sending a EAP message to the supplicant (the client workstation in this case) and will then send back an EAP response.

For this lab we will be focusing on wired networks and will be attempting to address the problem of visiting employees from company A from plugging in their equipment into Company B's infrastructure.

To start we will need the following components:

- A client machine running Windows 7 / 10 (192.168.20.2/24)
- A Cisco 2960 switch with IOS > 15 (192.168.20.1/24)
- A linux box running FreeRadius (192.168.20.254/24)

Switch

So let's firstly look at the switch portion - we'll configure dot1x and radius on the switch:

conf t
aaa new-model

radius server dot1x-auth-serv
 address ipv4 192.168.20.2 auth-port 1812 acct-port 1813
 timeout 3
 key (7) <sharedkey>

aaa group server radius dot1x-auth
server name dot1x-auth-serv

aaa authentication dot1x default group dot1x-auth
aaa accounting dot1x default start-stop group dot1x-auth
aaa authorization network default group dot1x-auth

and proceed by enabling dot1x:

dot1x system-auth-control

and we'll then enable it on the relevant ports:

int range gi0/1-5
switchport mode access
authentication port-control auto
dot1x pae authenticator

FreeRADIUS Server

We'll continue on the server by installing radiusd:

sudo yum install freeradius

and then use samba to communicate with the domain:

sudo yum install samba samba-common samba-common-tools krb5-workstation openldap-clients policycoreutils-python

(We are not actually setting up a samba server - instead just using some of the tools that are provided with it!)

vi /etc/samba/smb.conf


[global]
        workgroup = <domain-name>
        security = user
        winbind use default domain = no
        password server = <ad-server>
        realm = <domain-name>
        #passdb backend = tdbsam


[homes]
        comment = Home Directories
        valid users = %S, %D%w%S
        browseable = No
        read only = No
        inherit acls = Yes

and then edit the kerberos configuration:

vi /etc/krb5.conf

 Configuration snippets may be placed in this directory as well

includedir /etc/krb5.conf.d/

[logging]

 default = FILE:/var/log/krb5libs.log

 kdc = FILE:/var/log/krb5kdc.log

 admin_server = FILE:/var/log/kadmind.log

[libdefaults]

 dns_lookup_realm = false

 ticket_lifetime = 24h

 renew_lifetime = 7d

 forwardable = true

 rdns = false

 # default_realm = EXAMPLE.COM

 default_ccache_name = KEYRING:persistent:%{uid}

[realms]

 domain.com = {

  kdc = pdc.domain.com

 }

[domain_realm]

 .domain.com = DOMAIN.COM

 domain.com = DOMAIN.COM

and then modify NSS to ensure that it performs lookups using windbind:

vi /etc/nsswitch.conf

passwd:     files winbind

shadow:     files winbind

group:      files winbind

protocols:  files winbind

services:   files winbind

netgroup:   files winbind

automount:  files winbind

ensure samba starts on boot and restart the system:

sudo systemctl enable smb

sudo systemctl enable winbind

sudo shutdown -r now

Now join the domain with:

net join -U <admin-user>

and attempt to authenticate against a user with:

wbinfo -a <username>%<password>

should return something like:

Could not authenticate user user%pass with plaintext password

challenge/response password authentication succeeded

We also need to ensure NTLM authentication works (as this is what is used with FreeRadius):

ntlm_auth --request-nt-key --domain=<domain-name> --username=<username>

should return:

NT_STATUS_OK: Success (0x0)

(Providing the account is in good order e.g. not locked etc.)

The 'ntlm_auth' program needs access to the 'winbind_privileged' directory - so we should ensure that the user running the radius server is within the 'wbpriv' group:

usermod -a -G wbpriv radiusd

and then proceed to install and setup freeradius:

sudo yum install freeradius

sudo systemctl enable radiusd

mv /etc/raddb/clients.conf /etc/raddb/clients.conf.orig

vi /etc/raddb/clients.conf

and add the following:

client <switch-ip> {

        secret                = <secret-key>

        shortname             = <switch-ip>

        nastype               = cisco

}

We'll now configure mschap:

vi /etc/raddb/mods-enabled/mschap

and ensure the following is set:

with_ntdomain_hack = yes

ntlm_auth = "/usr/bin/ntlm_auth --request-nt-key --username=%{%{Stripped-User-Name}:-%{%{User-Name}:-None}} --challenge=%{%{mschap:Challenge}:-00} --nt-response=%{%{mschap:NT-Response}:-00}"

and the EAP configuration:

sudo vi /etc/raddb/mods-available/eap

Search for the following line:

tls-config tls-common

and uncomment:

random_file = /dev/urandom

Make sure your firewall is setup correctly:

sudo iptables -A INPUT -p udp -m state --state NEW -m udp --dport 1812 -j ACCEPT

sudo iptables -A INPUT -p udp -m state --state NEW -m udp --dport 1813 -j ACCEPT

and then test the configuration by running FreeRadius in test mode:

sudo radiusd -XXX

Then on the Windows 7 / 10 client workstation ensure that the 'Wired AutoConfig' service has been started (and has also been set to 'Automatic'.)

On the relevant NIC properties ensure that 'Enable 802.1X authentication' has been enabled:

Within Windows 10 you should not need to perform this - however it's always best to check the defaults just in case!

If you are not using a certificate ensure that the 'Verify the server's identity by validating the certificate' is unchecked as below (within the PEAP Settings):

Click 'Configure...' next to 'Secured password (EAP-MSCHAP v2) and ensure that 'Automatically use my Windows logon name and password' is ticked.

Finally hit 'OK' and back on the 'Authentication' tab - click on 'Additional settings...' and ensure 'Specify authentication mode' is ticked and is set to 'User authentication'.

We can now attempt to plug the client into the switch and with any luck we will obtain network access!

Sources

https://documentation.meraki.com/MS/Access_Control/Configuring_802.1X_Wired_Authentication_on_a_Windows_7_Client

http://wiki.freeradius.org/guide/freeradius-active-directory-integration-howto

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