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ClearPass – mail validation

If you would like to restrict or validate mail addresses during guest registration, you can use simply restrict domains. An example of a mail validation for the provided user and sponsor mail address is.

user mail validation (the mail address should not be a company mail address)

array (
‘deny’ =>
array (
0 => ‘booches.nl’,
),
‘allow’ =>
array (
),
)

sponsor mail validation (only company mail domain is allowed)

array (
‘allow’ =>
array (
0 => ‘booches.nl’,
),
‘deny’ =>
array (
0 => ‘*’,
),
)

These settings can be changed under “Validator Arguments” from the Form fields.

Guest Form

Guest Form

 

TrendMicro IMSVA – reject unknown recipients via LDAP

With the configuration and implementation of an anti-virus, anti-spam solution, I always check if the security appliance has the option to block unknown recipients via LDAP. This prevents unnecessary e-mail from being sent to the backend servers.

While configuring a TrendMicro IMSVA 8.0 I noticed that the LDAP option was available, as shown below.

ldap-check

The option can be found under Administration – IMSVA Configuration – SMTP routing. I enabled the option and configured a LDAP connection to the backend database. I started testing the LDAP check via telnet and noticed that all secondary e-mail addresses were rejected by the security appliance.

I started looking at the specific LDAP records from an user with a LDAP browser, like Softerra LDAP Browser. I noticed that all secondary e-mail addresses are under the name ProxyAddresses and the primary e-mail address falls under the name mail.

I started searching the TrendMicro knowledge base but couldn’t find a solution. I found an article about the problem, which also provided the correct solution. To enable TrendMicro IMSVA to check secondary e-mail addresses you have to login to the appliance via a SSH session and change some settings within the PostgreSQL database. You need to execute the following commands:

[root@mail ~]# cd /opt/trend/imss/PostgreSQL/bin/
[root@mail bin]# ./psql -U sa -d imss
Welcome to psql 8.1.3, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

imss=# update tb_global_setting set value=’proxyAddresses’ where name =’mail_attr’;

UPDATE 1
imss=# \q
[root@mail bin]#

Next I needed to reboot the server. After the reboot I did some more testing and this time all secondary e-mail addresses were accepted by the security appliance.

You can check your newly added entry in the PostgreSQL database with the following command:

imss=# select * from tb_global_setting where value=’proxyAddresses’;
section |   name    |     value      | inifile  | notes
———+———–+—————-+———-+——-
LDAP    | mail_attr | proxyAddresses | ldap.ini |
(1 row)

At the end I found the solution but I am very curious why this isn’t default behavior. I mean, I guess I am not the only one who is using secondary e-mail addresses?!?!

RSA 7.1 with On-Demand

RSA token security provides a way to strengthen the security on public services. Token authentication is most often implemented with hardware tokens. RSA 7.1 has additional methods of token authentication besides the hardware tokens:

  • Token delivery by SMS;
  • Token delivery by e-mail;

To enable the above features you have to install at least RSA 7.1 and obtain a On-Demand license, like shown below:

rsa-od-lic

Next I will show you how to configure token authentication for the delivery of tokens through SMS and e-mail. My test environment contains a RSA Authentication Manager 7.1 with RADIUS server installed on a Windows 2003 R2 server under VMware. The RSA server has a LDAP mapping to Active Directory for authenticating users.

E-MAIL

The first method explained is configuring RSA to deliver tokens to an e-mail address. The first step is configuring a SMTP server on the RSA server. In this scenario I create a SMTP connection to a Windows Exchange 2003 server. rsa-od-mailIn the Security Console, navigate to Setup – Instances and edit the instance you would like to use for the SMTP connection.

In the SMTP setup you need to configure the Hostname of the SMTP server and a “from” e-mail address. Some SMTP servers require authentication to use them as relay server. If your SMTP server requires authentication you can configure the appropriate user credentials. In my situation I only need to deliver mail to the @booches.nl domain, so I don’t need to configure authentication or assign relay rights to the RSA server on the Exchange server. If you would like to deliver e-mail to domains outside your mail environment, you have to configure authentication or relay access for the RSA server.

rsa-od-ena-mail After configuring the SMTP server you have to enable the ability to deliver token codes by e-mail. Navigate to Setup – Component Configuration – Authentication Manager – On-Demand Tokencodes in the Security Console. Enable the option “Delivery by E-mail” and choose the User Attribute to Provide E-mail Destination. This User Attribute is obtained by default through LDAP. In my scenario I use the e-mail field within Active Directory to obtain the specific e-mail address from a user.

rsa-od-user-mail From now on you can enable the usage of e-mail token delivery to your users. To accomplish this navigate to Identity – Users – Manage Existing and search for a specific user. Go to Security Tokens for the specific user and enable “On-Demand Tokencodes” and the specific settings, like shown in the picture. I configured an initial PIN for the user. The user should be able to obtain a token code through SMS via the Self-Service console. This portal can be reach via the URL: https://<ip address / FQDN RSA server>:7004/console-selfservice.

On-Demand token codes have a PIN code associated to the delivered token code. This PIN code is different from the PIN code of normal hardware tokens. I normally enable the On-Demand feature for a user and specify the first initial PIN code. After the user logs in with this PIN code, the PIN code needs to be changes. There are two ways of doing this:

  1. The user automatically receives a new PIN code, which is generated by the RSA server;
  2. The user has the option to manually specify a new PIN code;

rsa-od-token-policy Most often system engineers let the customers choose there own PIN code. Toggling between both settings is possible by changing the Token Policy. Changing the Token Policy is possible by navigating to Authentication – Policies – Token Policies.

SMS

To configure SMS token delivery you need some kind of method to send SMS messages. RSA and Clickatell have partnered to enable delivery of SecurID tokencodes to mobile devices via SMS/text. RSA Authentication 7.1 has a build-in method for delivering SMS messages through Clickatell. Click here to obtain more info about the partnership between RSA and Clickatell and how to register a (trial) Clickatell account.

The first step is to link a User Attribute from the Active Directory to RSA. This User Attribute contains the phone number for delivering the SMS. To such link navigate to Identity – Identity Attribute Definition – Add New.

rsa-od-mobile-link

Within Active Directory you can configure multiple Telephone numbers for a user. Because the SMS is sent to the users mobile phone, I enter the appropriate phone number under the mobile Telephone number of the users.

The picture shows how to configure the the User Attribute mapping. The Attribute Name is a user friendly name to identify the mapping. I choose Personal as Category and the Entry Type is optional. The users mobile phone number is displayed under Personal when editing the user.

The Identity Source Mapping defines the LDAP attribute to use for obtaining the mobile phone number from the user. This value has to be exactly the same as the LDAP value for the mobile phone number in Active Directory. I use Softerra’s LDAP browser to obtain this value from Active Directory. Softerra LDAP browser is a useful tool for browsing LDAP directories.

rsa-od-sms

The configuration of the SMS service provider can be found under Setup – Component Configuration – Authentication Manager – On-Demand Tokencodes.

You need to enable the option “Delivery by SMS”, choose the previously configured User Attribute, select your country code and provide the credentials for your Service Provider.

You can now switch between token code delivery by e-mail and SMS. A user has the option to choose the preferred delivery method via the Self-Service console. Users need access to the Self-Service console to request a token code. The Self-Service portal needs to be securely published to the internet. This can be achieved by using a reverse proxy or some comparable solution. The following PDF contains a quick howto for publishing the RSA environment securely to the internet.

Barracuda – Mail Protocol Violation

A customer updated the firmware from a Barracuda SPAM &Virus 300 firewall. The firmware was upgraded from version 3.4 to version 3.5.12.024. After the upgrade no email was coming in or going out through the Barracuda firewall.

All email was blocked and the following reason was visible in the message log:

Mail Protocol Violation

At first I couldn’t find a reason why all mail was blocked, so I contacted Barracuda and established a remote connection with Barracuda for remote troubleshooting. (I really like that feature). Finally the engineer found the problem. The Maximum Message Size value under Advanced – Email Protocol – SMTP Configuration was set to:

100000000000000000000000000000000000000 bytes

Yep, you read that correctly. I have no idea where that value came from. So I changed it back to the recommended value of 100 MB. After changing the value, mail started coming in and going out again through the Barracuda.

relays.ordb.org

Since the day before yesterday, some of our customers complained having problems with receiving e-mail. The senders from the e-mail noticed that their mail had been blocked by relays.ordb.org. This RBL is offline, according to this article, at least everybody thought. Seems to me, the RBL came online yesterday and blocked everything. I have heard some rumours about the RBL coming online and blocking everything, so postmaster become aware of false configuration of the RBL lists in the mail components. Our customers were using Microsoft Exchange servers and were still using relays.ordb.org in their Connection Filtering rules. After deleting the URL the mail began to flows like nothing happend.