Page 119 - Asterisk™: The Future of Telephony

FTP is currently the preferred method of allowing Polycom phones to obtain their
configuration. It works well, is fairly easy to configure, and is well supported by the
community.

FTP
FTP is currently our favorite way to configure Polycom sets. To install it on your CentOS
system, the following command will install VSFTPD, the Very Secure FTP Daemon:
# yum -y install vsftpd
Then, in order to lock things down, we need to prevent anonymous logins, with a simple
change to the vsftpd config file, /etc/vsftpd/vsftpd.conf:

# anonymous_enable=NO
Restart the server with service vsftpd restart. To ensure that the daemon runs after
every reboot, run chkconfig vsftpd on.
Now, we have to create a user account and group for the Polycom sets to use:

# groupadd PlcmSpIp
# useradd PlcmSpIp -g PlcmSpIp -p PlcmSpIp
# passwd PlcmSpIp
Set the password to PlcmSpIp (the default FTP password for Polycom sets). This can
be changed, but will then require manual configuration from each set in order to advise
them of their nonstandard credentials. ‖
For added security, let’s make sure the FTP server keeps that account in a chroot jail:
# echo PlcmSpIp >> /etc/vsftpd/vsftpd.chroot_list
That pretty much does it as far as preparing the operating system to provide the required
services to the phones.

The Polycom configuration files
While there seem to be a lot of different files that are needed to make a Polycom set
work, they are each fairly easy to understand.
The bootROM. This can best be described as the BIOS and operating system of the phone.
Perhaps there is a more technical explanation, but why make things confusing? The
bootROM should not need to be updated regularly, but it is good to keep an eye on
the current releases to see if a newer bootROM has features that will be of benefit in
your environment. This file will be named bootrom.ld.

‖ You can get into assigning complex and unguessable passwords for the phones to use, but unless you are
going to input the passwords into each phone manually, you’ll have to pass them their FTP user name and
password from the DHCP server. Any device that can get on the voice network can get the same information
from the DHCP server. We’re not telling you to ignore security, just don’t assume that creating separate
passwords for each phone is going to improve security.

Configuring SIP Telephones | 91