asterisk users - Aug 2006 - How to set externip in sip.conf automatically?

I need to give Asterisk access to my external IP address to prevent 
the NAT problem where caller cannot hear the callee's voice.

According to Asterisk - The Future of Telephony page 92 Environment 
Variables:

   "Environment variables are a way of accessing Unix environment 
variables from within Asterisk.  They are referenced in the form of
   ${ENV{var}}
where var is the Unix environment variable you wish to reference."

My external IP is placed each night in a file call /etc/myip and placed 
in the $MYIP variable by /etc/bashrc when an shell is loaded.

So I have /etc/myip refreshed each night in a cron job
and when a shell is opened /etc/bashrc does:
export MYIP=`cat /etc/myip`

To access the variable in sip.conf I have tried:

     externip=${ENV(EXTERNIP)}
and
     ${ENV($EXTERNIP)}
but neither seems to work.
Is this the correct syntax?  Did I misinterpret the book?

I say neither seems to work because When I hard code
externip=69.91.84.176
there are no NAT problems but when I try to access the $MYIP variable 
either of the ways above NAT prevents me hearing the callee's voice.

I have tried but not found a way to directly access the contents of MYIP 
to the console using the CLI.  Is there a way to see or set _any_ Linux 
enviromnent variable using the CLI?  More generally, how do I access the 
Linux shell from the CLI?

The problem with simply using
externip=69.91.94.176
is that number is subject to change and I don't know an easy way to 
automatically write the value into sip.conf programatically.

I could have just said "how do I do this" but wanted to show that
I've
done my homework.
Thanks for any help.

Larry

-- 
Larry Alkoff N2LA - Austin TX
Using Thunderbird on Linux

Larry, am I missing something but you seem to be putting the externip
into the MYIP variable but reading some EXTERNIP variable through
$ENV{}. Shouldn't you be doing something like externip=${ENV{MYIP}}?
The other issue is also the use of curly brackets as opposed to
paranthesis. The snip from the manual seems to use curly brackets but
you're using paranthesis in your example above.

Just silly things to watch out for :D

If you already have the IP in a file, why don't you set it up so the
file itself says:  externip=xx.xx.xx.xx and then do a #include in
sip.conf for the /etc/myip file?  I believe you'll have to do a sip
reload either way (which can obviously be part of your cron job) if
you're not already, but that should do what you're looking to do.

- Brad 

-----Original Message-----
From: asterisk-users-bounces@lists.digium.com
[mailto:asterisk-users-bounces@lists.digium.com] On Behalf Of Larry
Alkoff
Sent: Tuesday, August 22, 2006 9:34 PM
To: Asterisk-users; Austin-asterisk-users
Subject: [asterisk-users] How to set externip in sip.conf automatically?

  I need to give Asterisk access to my external IP address to prevent
the NAT problem where caller cannot hear the callee's voice.

According to Asterisk - The Future of Telephony page 92 Environment
Variables:

   "Environment variables are a way of accessing Unix environment
variables from within Asterisk.  They are referenced in the form of
   ${ENV{var}}
where var is the Unix environment variable you wish to reference."

My external IP is placed each night in a file call /etc/myip and placed
in the $MYIP variable by /etc/bashrc when an shell is loaded.

So I have /etc/myip refreshed each night in a cron job and when a shell
is opened /etc/bashrc does:
export MYIP=`cat /etc/myip`

To access the variable in sip.conf I have tried:

     externip=${ENV(EXTERNIP)}
and
     ${ENV($EXTERNIP)}
but neither seems to work.
Is this the correct syntax?  Did I misinterpret the book?

I say neither seems to work because When I hard code
externip=69.91.84.176
there are no NAT problems but when I try to access the $MYIP variable
either of the ways above NAT prevents me hearing the callee's voice.

I have tried but not found a way to directly access the contents of MYIP
to the console using the CLI.  Is there a way to see or set _any_ Linux
enviromnent variable using the CLI?  More generally, how do I access the
Linux shell from the CLI?

The problem with simply using
externip=69.91.94.176
is that number is subject to change and I don't know an easy way to
automatically write the value into sip.conf programatically.

I could have just said "how do I do this" but wanted to show that
I've
done my homework.
Thanks for any help.

Larry

--
Larry Alkoff N2LA - Austin TX
Using Thunderbird on Linux
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