Version 5.1
SysAdmin |
|---|
| ||||||||||
|
|
Version 5.1 |
||||||||||||||||||||||||||||||||
|
|
The CommuniGate Pro Server supports both clear-text and secure SASL authentication methods for the following TCP-based session-oriented protocols:
These secure methods allow mail clients to send encrypted passwords over non-encrypted and insecure links. If anybody can monitor your network traffic, SASL methods ensure that the real passwords cannot be detected by watching the client-server network traffic.
As an alternative to SASL methods, secure links (SSL/TLS) can be used between the client mailer and the server. When an SSL link is established, the entire network traffic between the server and the client is encrypted, and passwords can be sent in clear text over these secure links.
You can force an Account user to use either a SASL authentication method or SSL/TLS links if you enable the Secure Method Required option in the Account Settings. When this option is enabled, the Server rejects all authentication requests that send passwords in the clear text format over insecure links.
The CommuniGate Pro Server supports the following insecure (clear text) SASL authentication methods:
The CommuniGate Pro Server supports the following secure SASL authentication methods:
The CommuniGate Pro Server supports the following GSSAPI authentication methods:
The CommuniGate Pro Server supports the following SASL-EXTERNAL authentication methods:
The CommuniGate Pro Server supports the non-standard NTLM and MSN SASL methods used in Microsoft® products.
The CommuniGate Pro supports the secure APOP authentication method (used mostly for the POP protocol), and the insecure "regular login" method for the protocols that support Clear Text Login.
The CommuniGate Pro Server supports the special WebUser authenticaton method.
Use the WebAdmin Interface to open a Domain Settings page and find the Login Methods panel:
The Advertise options control only the session-type services (SMTP, POP, IMAP, ACAP, PWD, FTP),
and they do not have any effect on the transaction-type services (HTTP, SIP).
The Advertise options control only how the methods are advertised.
Client applications can still use all these methods, even if these options are switched off.
One password is the CommuniGate Pro's "own password ". This password is stored as an element of the Account Settings, and it can be used with the CommuniGate Pro Server only.
The other password is the "OS password". The user may be registered with the Server OS and the CommuniGate Pro Server can check the supplied password against the password set in the Server OS registration information for this user.
An account can have the External Password option enabled. In this case, user authentication is done using any custom authentication program running as a separate process (see below).
The system administrator can enable any set of passwords for any user account. On larger sites, it is better to enable these options using the Server-wide or Domain-wide Default Account Settings.
When several passwords are enabled for an account, the Server first checks the CommuniGate (internal) password, then the OS password, and then tries to use the External Authentication program. If at least one of these passwords matches the password presented with the client application, the application is granted access to that account.
CommuniGate passwords are strings stored in the Account Settings. Password strings can be stored in the clear-text format or in encoded format. The Password Encryption Account Setting specifies the encryption to use when the account password is updated. When this setting is changed, the currently stored password is not re-encrypted.
When the U-crpt Password Encryption option is selected, the CommuniGate
passwords are stored using the standard Unix crypt routine. If the
UB-crpt Password Encryption option is selected, an enchanced Blowfish-based
encryption is used.
U-crpt and UB-crpt methods implement a one-way encryption. As a result,
the Server cannot decrypt them into their original (clear text) form, and it cannot use them
for secure (SASL) Authentication Methods. Use these encryption methods
only if you need compatibility with legacy password strings, but cannot use the OS passwords -
it is usually more important to support "on-the-wire" security (using SASL methods), rather then
"on-the-disk" security (using one-way password encryption methods).
U-crpt passwords can contain special prefixes. These prefixes allow you to import passwords
encypted using other password encryption methods.
See the Migration section for more details.
Note: please remember that the plain Unix crypt routine uses only the first 8 symbols of the password string.
If the CommuniGate Password is absent or empty, it cannot be used to log into the Account even if the Use CommuniGate Password option is enabled. But if the user has logged in using the OS Password or the External Authentication method, the user can specify (update) the Account CommuniGate Password. This feature can be used to migrate users from legacy mail systems where you can not compose the list of accounts with non-crypted user passwords.
When the Server checks the OS password, it composes the username string using the Account OS User Name setting. When the default setting * is used, the composed OS user name is the same as the Account name. By changing the OS User Name settings you can use different OS usernames for Accounts in different CommuniGate Pro domains.
| Server Operating System | Notes about OS Passwords |
|---|---|
| Microsoft Windows 95/98/ME | OS does not support passwords, the Use OS Password option does not work. |
| Microsoft Windows 200x/XP/NT/Vista | The Windows NT domain authentication system is used. The Windows account used to run the CommuniGate Pro Messaging Server
should have the Act as part of the operating system privilege.
The --BatchLogon command line option can be used to tell the Server to use the LOGON_BATCH authentication method (if the option is not present, the LOGON_NETWORK method is used). The Server checks if the composed OS user name contains the percent (%) symbol.
If the symbol is found, the part of the name before that symbol is used as the Windows
account name, and the part after that symbol is used as the Windows domain name.
|
| Unix-based systems | The passwd and shadow or other OS-supported authentication mechanisms are used. |
| OS/400 systems | The user profile authentication mechanisms are used. |
| OpenVMS systems | The supplied user name and password strings are converted to uppercase, and then the OpenVMS authentication mechanisms are used. |
| BeOS | OS does not support passwords, the Use OS Password option does not work. |
The OS passwords are one-way-encrypted passwords. As a result, they cannot be used for Secure Authentication Methods.
The CommuniGate Pro Server supports the Kerberos authentication method. The Kerberos method is based on the "tickets" that client applications send to the server. These tickets are issued by Kerberos authorities (Key Distribution Centers, KDC) that share a common "key" with the Server. See the Kerberos documentation for the details.
To support Kerberos Authentication, you need to add Kerberos Server key(s) to the CommuniGate Pro Server, on the per-domain basis. Create a server "principal" in your KDC database. The principal name should be equal to the name of CommuniGate Pro Domain or one of its Domain Aliases. Export the created key as a keytab file.
Open the Domain Settings using the CommuniGate Pro WebAdmin Interface, and follow the Security and Kerberos links. The list of Domain Kerberos Keys will be displayed:
Each Domain can have several Kerberos Keys. To add Keys, click the browser file-select button and select the keytab file exported from KDC. Click the Import Keys button to add keys from the file to the set of the Domain Kerberos Keys.
To remove Keys, mark the Keys using checkboxes and click the Delete Marked button.
Domain Administrators can Add or Remove Kerberos Keys only if they have the KerberosKeys Access Right.
When the Server receives a Kerberos Ticket, it extracts the Server Name ("sname") from the Ticket. If the Server Name has only 1 component (domain.dom), this component is used as the target Domain name (ticket-domain-name). If the Server Name has 2 or more components (service/domain.dom), then the second component is used. The Server then builds a fictitious E-mail address LoginPage@ticket-domain-name and tries to route this address. This is the same routing mechanism as one used for finding the target Domain for HTTP requests.
If the target Domain is found, the Server looks for the proper key in the list of the Kerberos Keys for that Domain. If the Key is found, and the Ticket and Authorization info can be decrypted with that Key, the user is authenticated. The name of the Account is taken from the Client Name specified in the Ticket. That name must be a "simple" name, i.e. it cannot contain @ or % symbols.
CommuniGate Pro adds the name of the target Domain to the retrieved user name and uses the resulting E-mail address as the name of the Account to open.
Note: The Kerberos Authentication mechanism does NOT run the resulting user name via the Router. If it would use the Router, a name in one Domain could be routed to a name in a different Domain, so the Kerberos Keys valid for one Domain would provide access to Accounts in a different Domain. As a side effect, the Account Aliases cannot be used in Kerberos tickets.
Only Accounts with enabled Kerberos Authentication method can be accessed using Kerberos tickets.
You may want to use Microsoft Active Directory as your Kerberos Key Distribution Center (KDC). Follow these steps:
See the Microsoft Knowledge Base artcile Q324144 for more details.
If you want to use Kerberos Authentication (Single Sign-on) with Microsoft browsers, please read the "HTTP-Based Cross-Platform Authentication via the Negotiate Protocol" article in the Microsoft documentation set (MSDN).
The CommuniGate Pro Server supports the Client Certificate authentication method. This method can be used when clients connect to the Server via secure SSL/TLS connections. The Server may request a client to send a Client Certificate (installed on the client computer), signed with the Trusted Certificate selected on the Server for the target Domain.
If a client sends such a Certificate, the E-mail address specified in the Certificate subjectAltName element (if any) or in the Subject element E-mail field can be used for the Certificate-based Authentication. It is is interpreted as the name of the CommuniGate Pro Account to log into.
Note: The Certificate Authentication mechanism does NOT run the provided E-mail address via the Router. If it would use the Router, a name in one Domain could be routed to a name in a different Domain, so the Trusted Certificates valid for one Domain would provide access to Accounts in a different Domain. As a side effect, the Account Aliases cannot be used with the Certificate Authentication mechanism.
Only Accounts with enabled Certificate Authentication method can be accessed using Client Certificates.
See the PKI section for more details.
The CommuniGate Pro Server can use an external Helper program for user authentication. That program should be created by your own technical staff and it can implement authentication mechanisms required at your site but not supported directly with the CommuniGate Pro Server.
The External Authenticator can also be used to automatically provision Accounts based on some external data source, and/or to assist with the Router operations.
The External Authenticator program name and its optional parameters should be specified using the WebAdmin Helpers page. Open the General page in the Settings realm, and click the Helpers link:
See the Helper Programs section to learn about these options.
The External Authentication module System Log records are marked with the EXTAUTH tag.
If the External Authentication program is not running, all External Authentication requests are rejected.
To create your own External Authentication program, see the Helpers section to learn about the External Authentication interface protocol.
Sample External Authentication programs and scripts can be found at the Authentication Helpers site.
Some spammers use 'brute force' attacks on mail systems, sending random names and passwords to system POP, IMAP, and other access ports. If the system sends different error messages for the "unknown account" and "incorrect password" situations, the attacker can harvest a large portion of the system Account names and then use those names for spam mailings.
Use the WebAdmin Interface to configure the Login Security options. Open the General pages in the Settings realm, and find the Login Security panel on the Others page:
The CommuniGate Pro server can temporarily disable all types of login operation for an Account that has seen too many incorrect login attempts. The Login Security panel shown above allows you to specify a time period and the number of incorrect login attempts that a user or users can make before the Account is disabled for login operations. The Account is re-enabled after the same period of time.
In order to control, monitor, and maintain the CommuniGate Pro Server, one Postmaster Account is usually enough. But you may want to allow other users to connect to the administrator intefraces of your CommuniGate Pro Server: for example, you may want to allow an operator to monitor the Logs, but you do not want to grant that operator all Postmaster access rights.
You should be logged in as the Postmaster, or other Account with the "Can Do Everying" right in order to assign Access Rights.
To grant access rights to a user and/or to revoke those rights, open that user Account (the Account Setting page), and click the Access Rights link. The Access Rights page will appear.
The page lists all Access Rights and the rights granted to the selected user are marked.
The following access rights can be granted only to the users (accounts) in the Main Domain:
The following access rights can be granted to users in any domain:
Initially, the user Postmaster in the main domain has the Master Access right.
Select the desired Access Rights and click the Update button.
The Access Rights are stored in one file for each domain, the Access.settings file stored in the Settings subdirectory of the domain directory. This makes it easy to check who is granted the Server Administration rights.
If you do not plan to support mobile users, you may want to restrict access to the Server accounts. Use the following option on the Client IP Addresses page:
When an access module accepts a connection from an unlisted network address, and this option is selected, the module sends an error code to the client application, and the connection is closed immediately. Links with the rest of the Internet will be used only for mail Transfer, Real-Time Signals exchange, and for HTTP access to Account File Storage.
When this option is selected, the SMTP AUTH operation can be used only if a client mailer or server connects from the network address included into Client Addresses list.
When this option is selected, any Signaling operation that requires authentication
can be used only if a client device or server connects from the network address included
into Client Addresses list.
Note: Before you enable this option, make sure
that the network address you are currently using is included into the Client Addresses list: otherwise
you will immediately lose HTTP Admin access to the Server.
You can also specify the access restrictions on the lower (TCP) connection level. For each service (module), open the Listener page and specify the addresses the service (module) should or should not accept connections from. If a connection comes from an address that is not included into the Grant list or is included into the Deny list, the connection is closed immediately, and no module-level operations are performed.
The CommuniGate Pro Server supports impersonating - a login mode when the credentials
are supplied for one Account (the Authentication Account), while a different Account (the
Authorisation Account) is being opened.
It can also be used for Real-Time Registration.
Impersonating is supported for PLAIN and GSSAPI Authentication methods.
When Impersonating is used, the Server checks if the authentication Account credentials are valid, and if the requested service is allowed for that Account. It also checks if the Authentication Account has the CanImpersonate Domain access right.
The CommuniGate Pro Server supports the special WebUser authenticaton method.
This method uses the session ID of a WebUser or XIMSS session
instead of the Account password.
The method is useful for CGI programs and scripts.
This method is disabled by default (see above).
The method is a SASL method and requires "immediate" parameters in the authentication protocol command. The first parameter
is the Account name, the second parameter, separated with the space symbol, is the WebUser session ID.
The WebUser authenticaiton operation for the PWD module is:
If the user john@doe.dom has an open WebUser Session with the 114-bXaKw92JK1pZVB5taj1r ID,
then the PWD command:
AUTH WEBUSER john@doe.dom 114-bXaKw92JK1pZVB5taj1r
opens the john@doe.dom account in this PWD session.