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81 lines
2.9 KiB
TeX
81 lines
2.9 KiB
TeX
\subsection{Introduction}
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PLEASE READ THE FOLLOWING IMPORTANT SECURITY RELATED INFORMATION.
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IMPROPER CONFIGURATION OF ASTERISK COULD ALLOW UNAUTHORIZED USE OF YOUR
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FACILITIES, POTENTIALLY INCURRING SUBSTANTIAL CHARGES.
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Asterisk security involves both network security (encryption, authentication)
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as well as dialplan security (authorization - who can access services in
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your pbx). If you are setting up Asterisk in production use, please make
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sure you understand the issues involved.
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\subsection{Network Security}
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If you install Asterisk and use the "make samples" command to install
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a demonstration configuration, Asterisk will open a few ports for accepting
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VoIP calls. Check the channel configuration files for the ports and IP addresses.
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If you enable the manager interface in manager.conf, please make sure that
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you access manager in a safe environment or protect it with SSH or other
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VPN solutions.
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For all TCP/IP connections in Asterisk, you can set ACL lists that
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will permit or deny network access to Asterisk services. Please check
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the "permit" and "deny" configuration options in manager.conf and
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the VoIP channel configurations - i.e. sip.conf and iax.conf.
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The IAX2 protocol supports strong RSA key authentication as well as
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AES encryption of voice and signalling. The SIP channel does not
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support encryption in this version of Asterisk.
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\subsection{Dialplan Security}
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First and foremost remember this:
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USE THE EXTENSION CONTEXTS TO ISOLATE OUTGOING OR TOLL SERVICES FROM ANY
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INCOMING CONNECTIONS.
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You should consider that if any channel, incoming line, etc can enter an
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extension context that it has the capability of accessing any extension
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within that context.
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Therefore, you should NOT allow access to outgoing or toll services in
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contexts that are accessible (especially without a password) from incoming
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channels, be they IAX channels, FX or other trunks, or even untrusted
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stations within you network. In particular, never ever put outgoing toll
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services in the "default" context. To make things easier, you can include
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the "default" context within other private contexts by using:
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\begin{astlisting}
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\begin{verbatim}
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include => default
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\end{verbatim}
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\end{astlisting}
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in the appropriate section. A well designed PBX might look like this:
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\begin{astlisting}
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\begin{verbatim}
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[longdistance]
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exten => _91NXXNXXXXXX,1,Dial(DAHDI/g2/${EXTEN:1})
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include => local
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[local]
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exten => _9NXXNXXX,1,Dial(DAHDI/g2/${EXTEN:1})
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include => default
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[default]
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exten => 6123,Dial(DAHDI/1)
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\end{verbatim}
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\end{astlisting}
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DON'T FORGET TO TAKE THE DEMO CONTEXT OUT OF YOUR DEFAULT CONTEXT. There
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isn't really a security reason, it just will keep people from wanting to
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play with your Asterisk setup remotely.
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\subsection{Log Security}
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Please note that the Asterisk log files, as well as information printed to the
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Asterisk CLI, may contain sensitive information such as passwords and call
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history. Keep this in mind when providing access to these resources.
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