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Version 6.3
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Version 6.3 |
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Authentication MethodsThe 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 SessionID Authentication 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).
Account Passwords
The CommuniGate Pro Server supports several passwords for each account.
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. Additional variants of CommuniGate Pro internal password can be specified with tag names. When authenticating with these tagged passwords the authenticating client application should specify the password tag after account name separated with $ symbol: user$tag. 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 Authentication URI specified that is used to authenticate to an external LDAP server. This method works only with Clear Text authentication methods. 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, then Authentication URI if not empty, 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 PasswordsCommuniGate 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 enhanced Blowfish-based
encryption is used.
U-crpt passwords can contain special prefixes. These prefixes allow you to import passwords
encrypted using other password encryption methods.
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 their non-encrypted (plain text) user passwords. OS PasswordsWhen 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.
The OS passwords are one-way-encrypted passwords. As a result, they cannot be used for Secure Authentication Methods. Kerberos AuthenticationThe 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: after the resulting user name is processed with the Router, it checks that the target Account belongs to the same Domain as the Domain the Kerberos Key was retrieved from, so Administrators of one Domain cannot create Kerberos tickets allowing users to access Accounts in other CommuniGate Pro Domains. Only Accounts with enabled Kerberos Authentication method can be accessed using Kerberos tickets. Integrating with Microsoft Active DirectoryYou may want to use Microsoft Active Directory as your Kerberos Key Distribution Center (KDC). Follow these steps:
See the Microsoft Knowledge Base article 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). LDAP AuthenticationThe CommuniGate Pro Server supports the LDAP URI authentication method when the URI has the form ldap(s)://address[:port]/parameters. This method is based on the LDAP protocol BIND request being sent to an external LDAP server accessible at address[:port] with authentication DN built from the parameters part of the URI and the password as received in the access protocol request being authenticated. In this scenario only the clear text authentication methods are supported between CommuniGate Pro and the connecting client. If the External LDAP server answers positively to the BIND request with BIND DN built from the parameters part, then the user can log into the Account. The asterisk (*) symbol is substituted in the parameters part of the URI with the CommuniGate Pro Account name, the ^0 is substituted with the CommuniGate Pro Domain name. Note: for Microsoft Active Directory LDAP server as parameters instead of DN you can use DOMAIN\account or account@domain.dom where DOMAIN is the short Windows domain name, domain.dom is the full Windows domain name, and account is the value of sAMAccountName attribute of the account record in the Active Directory.
Certificate AuthenticationThe 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 interpreted as the name of the CommuniGate Pro Account to log into. Note: after the supplied E-mail address is processed with the Router, it checks that the target Account belongs to the same Domain as the Domain the used to verify the supplied Certificate, so Administrators of one Domain cannot create Certificates allowing users to access Accounts in other CommuniGate Pro Domains. Only Accounts with enabled Certificate Authentication method can be accessed using Client Certificates. See the PKI section for more details. External AuthenticationThe 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:
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 Helper Applications section to learn about the External Authentication interface protocol. Sample External Authentication programs and scripts can be found at the Authentication Helpers site. Account Name HarvestingSome 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 Account Settings 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. Granting Access Rights to UsersIn 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 interfaces 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 Everything" 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 a single file for each Domain, the Access.settings file stored in the Settings subdirectory of the Domain file directory. This makes it easy to check who is granted the Server Administration rights. Restricting AccessIf 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:
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. ImpersonatingThe CommuniGate Pro Server supports impersonating - a login mode when the credentials
are supplied for one Account (the Authentication Account), while a different Account (the
Authorization Account) is being opened.
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 SessionID Authentication MethodThe CommuniGate Pro Server supports the special SessionID Authentication method.
This method uses the session ID of a WebUser or XIMSS session
instead of the Account password.
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 session ID.
The SESSIONID authentication operation for the IMAP module is:
If the user john@doe.dom has an open WebUser Session with the 114-bXaKw92JK1pZVB5taj1r ID,
then the PWD command:
Access Control Lists (ACLs)The Account owner can grant certain rights to other users: a right to access certain Mailboxes, a right to control telephony features, etc. Each element of the Access Control List contains a name and a set of access rights granted to that name. An ACL element name can be:
An ACL element name can have a + or a - prefix. Account owners always have all access rights to all objects (Mailboxes, functions) in their own Accounts. For any other someaccount Account, the effective access rights are checked. The effective access rights are calculated in several steps:
When granting access rights, the real Account names, not Account Aliases should be used. If an Account j.smith has two aliases john.smith and jonny, the access rights should be granted to the name j.smith.
The Access Control Lists can be set and modified using the WebUser Interface, a XIMSS, a MAPI, or a decent IMAP client. | |||||||||||||||||||||||||||||||||||
