System information

Option Value/Example Notes
the mailboxes for changes, which will trigger proper message wait-
ing indication (MWI) updates.
pollfreq 30 Used in concert with pollmailboxes, this option specifies the
number of seconds to wait between mailbox polls.
imapgreetings no, yes This enables/disables remote storage of greetings in the IMAP folder.
For more details, see Chapter 18.
greetingsfolder INBOX If you’ve enabled imapgreetings, this parameter allows you to
define the folder your greetings will be stored in (defaults to INBOX).
imapparentfolder INBOX IMAP servers can handle parent folders in different ways. This field
allows you to specify the parent folder for your mailboxes. For more
details, see Chapter 7.
a
The separator that is used for each format option must be the pipe (|) character.
b
Sending email from Asterisk can require some careful configuration, because many spam filters will find Asterisk messages suspicious and
will simply ignore them. We talk more about how to set email for Asterisk in Chapter 18.
c
Yes, you read that correctly: megabytes.
d
The Analog Display Services Interface is a standard that allows for more complex feature interactions through the use of the phone display
and menus. With the advent of VoIP telephones, ADSI’s popularity has decreased in recent years.
External Validation of Voicemail Passwords
By default, Asterisk does not validate user passwords to ensure they are at least some-
what secure. Anyone who maintains voicemail systems will tell you that a large per-
centage of mailbox users set their passwords to something like 1234 or 1111, or some
other string that’s easy to guess. This represents a huge security hole in the voicemail
system.
Since the app_voicemail.so module does not have the built-in ability to validate pass-
words, the settings externpass, externpassnotify, and externpasscheck allow you to
validate them using an external program. Asterisk will call the program based on the
path you specify, and pass it the following arguments:
mailbox context oldpass newpass
The script will then evaluate the arguments based on rules that you defined in the
external script and, based on your rules, it should return to Asterisk a value of VALID
for success or INVALID for failure (actually, the return value for a failed password can
be anything except the words VALID or FAILURE). This value is typically printed to
stdout. If the script returns INVALID, Asterisk will play an invalid-password prompt and
the user will need to attempt something different.
Ideally, you would want to implement rules such as the following:
• Passwords must be a minimum of six digits in length
• Passwords must not be strings of repeated digits (e.g., 111111)
• Passwords must not be strings of contiguous digits (e.g., 123456 or 987654)
162 | Chapter 8: Voicemail