[Freeswitch-users] NAT traversal questions - (long)...

Sun Aug 29 14:16:11 PDT 2010

Yeah, I read more into this last night and your 100% right on about most
firewalls not supporting this out of the box...You should hookup your IPCOP
box and unload the ip_conntrack_sip & ip_nat_sip modules to see if it breaks
in a similar fashion.

Brian

On Sun, Aug 29, 2010 at 1:48 PM, Tony Graziano <tgraziano at myitdepartment.net
> wrote:

> ANY generic firewall does not have any type of symmetric nat turned on by
> default.
>
> MANY consumer based routers are also INCAPABLE of doing so (MANUAL).
>
> The default use for pfsense is AUTOMATIC, but at least it has an easy way
> to do MANUAL (AON), easier, IMO than IPTABLES.
>
>
>
> On Sun, Aug 29, 2010 at 2:00 PM, Dave Redmore <
> dave.redmore at spigotsystems.com> wrote:
>
>> Thanks for your help/thoughts Tony.
>>
>> I just confirmed that siproxd is not installed - SSH'd in and checked
>> running processes to be sure.
>>
>> Like I said earlier - I can make it work - I have disabled the automatic
>> outbound NAT and set up AON (Advanced Outbound Nat).  It is just that I want
>> to understand what I am seeing so that  I can learn from all this.
>>
>> Here is one thing - If Freeswitch flagged my pfsense connection as being
>> behind NAT - would it then compensate for the Source port being 11521 (per
>> the packet capture in the original email)?  Am I totally wrong in thinking
>> that it would be "normal" to see packets with the source port changed for
>> users behind generic NAT firewalls?
>>
>> I might try hooking the IPCOP box back up and doing a capture of that, so
>> I can see what is different between the IPCOP (worked "out of the box") vs.
>> the pfsense.
>>
>> Dave
>>
>>
>> ----- Original Message -----
>> From: "Tony Graziano" <tgraziano at myitdepartment.net>
>> To: "FreeSWITCH Users Help" <freeswitch-users at lists.freeswitch.org>
>> Sent: Sunday, August 29, 2010 10:53:05 AM GMT -06:00 US/Canada Central
>> Subject: Re: [Freeswitch-users] NAT traversal questions - (long)...
>>
>> If pfsense and your FS install are on the same subnet then "something"
>> must be sitting in between to randomize the ports. In the 1.2.x install of
>> pfsense, siproxd is installed by default. There is also a default rule for
>> port 5060 that is in pfsense. I suggest removing the filters AND rules and
>> starting from scratch.
>>
>> I believe this is also the default, and undesired installation, when
>> installing a sip system behind it, even for the beta snapshots of pfsense
>> 2.0. Please check your installed packages. Please remove any rules you did
>> not create for the network and start over. What you are describing sounds to
>> me the siproxd IS/WAS installed. It picks up on anything on the LAN and
>> randomizes the port. It's a very common thing with pfsense.
>>
>> On Sun, Aug 29, 2010 at 11:26 AM, Dave Redmore <
>> dave.redmore at spigotsystems.com> wrote:
>>
>>> Confusion abounds here - sorry if I am being obtuse...
>>>
>>> A few points on all this -
>>>
>>> 1 - sipproxd is NOT installed on the firewall
>>>
>>> 2 - I am confused by the source port randomization issue.  I think that
>>> what pfsense does by default is randomize the source port translations,
>>> rather than using the same source port translations for all connections from
>>> an internal host.  This is completely different from the issue of telling
>>> pfsense to not change the source port at all - i.e. create a Static Port
>>> NAT.
>>>
>>> 3 - One of the things that I find most confusing about what I saw/see in
>>> the packet captures is that I EXPECTED to see non-SIP ports as the source
>>> port for the registration requests.  What we commonly call NAT is more
>>> accurately described as PAT (Port Address Translation) - it functions by
>>> translating the source port of requests in and out of the firewall.  It is
>>> one of the FEW things that I like about Cisco is that they more accurately
>>> use the terms NAT and PAT.
>>>
>>> 4 - So, that brings me back to why am I NOT seeing random source ports -
>>> why is Freeswitch NOT tagging my connection from pfsense as being NAT'd?
>>>
>>> Dave
>>>
>>>
>>>
>>> To start receiving Spigot Network's once a month newsletter filled with
>>> interesting technology news and great offers click SUBSCRIBE<http://www.spigotnetworks.com/lists/?p=subscribe&id=1>
>>>
>>>
>>> ----- Original Message -----
>>> From: "Tony Graziano" <tgraziano at myitdepartment.net>
>>> To: "FreeSWITCH Users Help" <freeswitch-users at lists.freeswitch.org>
>>> Sent: Sunday, August 29, 2010 7:11:26 AM GMT -06:00 US/Canada Central
>>> Subject: Re: [Freeswitch-users] NAT traversal questions - (long)...
>>>
>>> Yeah, the sipxroxd is in the installed packages on his build. Remove
>>> the intsalled package and make sure the default rule for outgoing
>>> traffic is set for manual/static nat, not automatic.
>>>
>>> http://blog.myitdepartment.net/?p=37
>>>
>>> On Sun, Aug 29, 2010 at 7:40 AM, Tony Graziano
>>> <tgraziano at myitdepartment.net> wrote:
>>> > Ipcop has a similar setting to pfsense. You probably missed it.
>>> >
>>> > MOST FIREWALLS do not use static port NAT. The default rules for
>>> > pfsense (and packages) for port 5060 should be removed.
>>> >
>>> > On your outbound rule for your LAN static port nat needs to be
>>> > enabled. Once you do that recreate the nat rules AND remove the
>>> > siproxd package by default.
>>> >
>>> > This is really a pfsense firewall question, it is clear static port
>>> > was not enabled so the source port was re-written because that is what
>>> > MOST firewalls do by default.
>>> >
>>> > On 8/29/10, Dave  Redmore <dave.redmore at spigotsystems.com> wrote:
>>> >> Hello All,
>>> >>
>>> >> I ran into an issue today that has burned up most of my day
>>> troubleshooting.
>>> >> I have resolved the problem, but would really like to understand what
>>> caused
>>> >> it, or some of the internal Freeswitch plumbing that is at play so
>>> that I
>>> >> can learn something from all of this time I have invested.
>>> >>
>>> >> I have a Freeswitch server running that acts as a proxy to an account
>>> with
>>> >> an ITSP for doing T38 faxing. The Freeswitch server has a public IP
>>> address
>>> >> - there are four "users" who register simple FXS ATAs to my server and
>>> it
>>> >> then proxies to the ITSP using the "proxy_media" functionality. It has
>>> been
>>> >> working very well for the last 6 months or so. I have never had to
>>> deal with
>>> >> any NAT traversal issues - I just point the ATA to the IP to register
>>> and
>>> >> everything is great.
>>> >>
>>> >> Here is what the four users "looked" like -
>>> >>
>>> >> User1 : Grandstream HT-287 -> DD-WRT Router (NAT) -> Internet ->
>>> Freeswitch
>>> >> Proxy
>>> >> User2 : Grandstream HT-503 -> DD-WRT Router (NAT) -> Internet ->
>>> Freeswitch
>>> >> Proxy
>>> >> User3 : Grandstream HT-502 -> Comcast/SMC Router (NAT) -> Internet ->
>>> >> Freeswitch Proxy
>>> >> User4 : Grandstream HT-287 -> IPCOP 1.4.11 (NAT) -> Comcast Gateway ->
>>> >> Freeswitch Proxy
>>> >>
>>> >> (User4 is my office, so the IPCOP firewall and the Freeswitch Proxy
>>> sit on
>>> >> the same Comcast Gateway)
>>> >>
>>> >> As I said, this all worked perfectly without any need to "fiddle" with
>>> >> anything on any firewalls - worked right out of the box.
>>> >>
>>> >> So, today I changed out my IPCOP firewall for a pfsense firewall - and
>>> my
>>> >> HT-287 would no longer register.
>>> >>
>>> >> After much head-scratching, packet captures, etc. I found that I
>>> needed to
>>> >> set up a Static Port NAT for the port the HT-287 was using (5062) in
>>> order
>>> >> to get this to work.
>>> >>
>>> >> So, I see WHAT is happening, but I really want to know WHY it is
>>> happening.
>>> >>
>>> >> Here are the gory details:
>>> >>
>>> >> The sofia status of the profile looks like this - when the I have the
>>> Static
>>> >> Port NAT in place (details changed for security):
>>> >>
>>> >> _______________________________________________________________
>>> >> Call-ID: 0e551b3c694a793c at 192.168.1.137
>>> >> User: 8885554525 at 173.11.22.111
>>> >> Contact: "user"
>>> >> <sip:8885554525 at 192.168.1.137 <sip%3A8885554525 at 192.168.1.137>
>>> ;fs_nat=yes;fs_path=sip%3A8885554525%40173.22.22.55%3A5060>
>>> >> Agent: Grandstream HT287 1.1.0.45 DevId 000b821203c5
>>> >> Status: Registered(UDP-NAT)(unknown) EXP(2010-08-29 01:17:03)
>>> >> Host: 173-11-22-111-illinois.hfc.comcastbusiness.net
>>> >> IP: 173.22.22.55
>>> >> Port: 5060
>>> >> Auth-User: 8885554525
>>> >> Auth-Realm: 173.11.22.111
>>> >> MWI-Account: 8885554525 at 173.11.22.111
>>> >>
>>> >> Call-ID: 1716488819-5062-1 at 192.168.7.150
>>> >> User: 8885554544 at 173.11.22.111
>>> >> Contact: "user" <sip:8885554544 at 192.168.7.150:5062
>>> ;user=phone;fs_nat=yes;
>>> >> fs_path=sip%3A8885554544%4098.255.0.11%3A5062%3Buser%3Dphone>
>>> >> Agent: Grandstream HT-502 V1.1B 1.0.1.63
>>> >> Status: Registered(UDP-NAT)(unknown) EXP(2010-08-29 01:48:35)
>>> >> Host: 173-11-22-111-illinois.hfc.comcastbusiness.net
>>> >> IP: 98.255.0.11
>>> >> Port: 5062
>>> >> Auth-User: 8885554544
>>> >> Auth-Realm: 173.11.22.111
>>> >> MWI-Account: 8885554544 at 173.11.22.111
>>> >>
>>> >> Call-ID: 090ee80e1a0ec9ed at 10.8.11.149
>>> >> User: 8885554549 at 173.11.22.111
>>> >> Contact: "user" <sip:8885554549 at 10.8.11.149:5062>
>>> >> Agent: Grandstream HT287 1.1.0.45 DevId 000b82127390
>>> >> Status: Registered(UDP)(unknown) EXP(2010-08-29 02:00:42)
>>> >> Host: 173-11-22-111-illinois.hfc.comcastbusiness.net
>>> >> IP: 173.11.22.99
>>> >> Port: 5062
>>> >> Auth-User: 8885554549
>>> >> Auth-Realm: 173.11.22.111
>>> >> MWI-Account: 8885554549 at 173.11.22.111
>>> >>
>>> >> Call-ID: 1035241259-5060-1 at 10.1.10.150
>>> >> User: 8885554547 at 173.11.22.111
>>> >> Contact: "user" <sip:8885554547 at 10.1.10.150:5060
>>> ;user=phone;fs_nat=yes;fs
>>> >> _path=sip%3A8885554547%4098.222.55.100%3A5060%3Buser%3Dphone>
>>> >> Agent: Grandstream HT-503 V1.1B 1.0.1.63
>>> >> Status: Registered(UDP-NAT)(unknown) EXP(2010-08-29 00:15:09)
>>> >> Host: 173-11-22-111-illinois.hfc.comcastbusiness.net
>>> >> IP: 98.222.55.100
>>> >> Port: 5060
>>> >> Auth-User: 8885554547
>>> >> Auth-Realm: 173.11.22.111
>>> >> MWI-Account: 8885554547 at 173.11.22.111
>>> >> ___________________________________________________________
>>> >>
>>> >> The "User4" account is in red. The "Contact" field is substantially
>>> >> different and the "Status" indicates "Registered (UDP)", rather than
>>> >> "Registered (UDP-NAT)" as the others.
>>> >>
>>> >> When I do a packet capture on the external NIC interface (eth0) - I
>>> see the
>>> >> following when the HT-287 tries to register and the Static Port NAT is
>>> NOT
>>> >> in place:
>>> >>
>>> >> ___________________________________________________________________
>>> >> Internet Protocol, Src: 173.11.22.99 (173.11.22.99), Dst:
>>> 173.11.22.111
>>> >> (173.11.22.111)
>>> >> User Datagram Protocol, Src Port: 11521 (11521), Dst Port: 5090 (5090)
>>> >> Session Initiation Protocol
>>> >> Request-Line: REGISTER sip:173.11.22.111:5090 SIP/2.0
>>> >> Method: REGISTER
>>> >> Request-URI: sip:173.11.22.111:5090
>>> >> Request-URI Host Part: 173.11.22.111
>>> >> Request-URI Host Port: 5090
>>> >> Message Header
>>> >> Via: SIP/2.0/UDP 10.8.11.149:5062;branch=z9hG4bKda48f838c8689e41
>>> >> Transport: UDP
>>> >> Sent-by Address: 10.8.11.149
>>> >> Sent-by port: 5062
>>> >> Branch: z9hG4bKda48f838c8689e41
>>> >> From: <sip:8885554549 at 173.11.22.111:5090>;tag=c8a0d452edc5ac4b
>>> >> SIP from address: sip:8885554549 at 173.11.22.111:5090
>>> >> SIP tag: c8a0d452edc5ac4b
>>> >> To: <sip:8885554549 at 173.11.22.111:5090>
>>> >> Contact: <sip:88855564549 at 10.8.11.149:5062>
>>> >> Contact Binding: <sip:8885554549 at 10.8.11.149:5062>
>>> >> Supported: replaces, timer
>>> >> Call-ID: aa77d777bae71be6 at 10.8.11.149
>>> >> CSeq: 100 REGISTER
>>> >> Sequence Number: 100
>>> >> Method: REGISTER
>>> >> Expires: 3600
>>> >> User-Agent: Grandstream HT287 1.1.0.45 DevId 000b82127390
>>> >> Max-Forwards: 70
>>> >> Allow:
>>> INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE,UPDATE
>>> >> Content-Length: 0
>>> >> _______________________________________________________________
>>> >>
>>> >> When Freeswitch replies back with a "401 Unauthorized" - asking for
>>> further
>>> >> Auth - it replies back to port 5062 - so the packet never comes back
>>> >> (pfsense is looking for a packet back on port 11521 in this case).
>>> >>
>>> >> If I put the Static Port NAT in place - all is well, because the
>>> "Source"
>>> >> port shows as "5062" - the rest of the packet looks pretty much the
>>> same.
>>> >>
>>> >> Now, here is a packet coming from one of the other Users - this one
>>> comes
>>> >> through a DD-WRT router - here we see that the Source Port is 5060 :
>>> >>
>>> >> _________________________________________________________________
>>> >> Internet Protocol, Src: 173.22.22.55 (173.22.22.55), Dst:
>>> 173.11.22.111
>>> >> (173.11.22.111)
>>> >> User Datagram Protocol, Src Port: sip (5060), Dst Port: 5090 (5090)
>>> >> Session Initiation Protocol
>>> >> Request-Line: REGISTER sip:173.11.22.111:5090 SIP/2.0
>>> >> Method: REGISTER
>>> >> Request-URI: sip:173.11.22.111:5090
>>> >> [Resent Packet: False]
>>> >> Message Header
>>> >> Via: SIP/2.0/UDP 192.168.1.137;branch=z9hG4bK665bc67a1c64292b
>>> >> Transport: UDP
>>> >> Sent-by Address: 192.168.1.137
>>> >> Branch: z9hG4bK665bc67a1c64292b
>>> >> From: "fax" <sip:8885554525 at 173.11.22.111:5090>;tag=8dc68b35111c4261
>>> >> To: <sip:8156564525 at 173.15.28.101:5090>
>>> >> Contact: <sip:8885554525 at 192.168.1.137<sip%3A8885554525 at 192.168.1.137>
>>> >
>>> >> Contact Binding: <sip:8885554525 at 192.168.1.137<sip%3A8885554525 at 192.168.1.137>
>>> >
>>> >> Call-ID: 0e551b3c694a793c at 192.168.1.137
>>> >> CSeq: 503 REGISTER
>>> >> Sequence Number: 503
>>> >> Method: REGISTER
>>> >> Expires: 3600
>>> >> User-Agent: Grandstream HT287 1.1.0.45 DevId 000b821203c5
>>> >> Max-Forwards: 70
>>> >> Allow:
>>> INVITE,ACK,CANCEL,BYE,NOTIFY,REFER,OPTIONS,INFO,SUBSCRIBE,UPDATE
>>> >> Content-Length: 0
>>> >> ______________________________________________________________________
>>> >>
>>> >> Here is one more packet coming from a Comcast/SMC Router - again, the
>>> source
>>> >> port is correct:
>>> >>
>>> >> ______________________________________________________________________
>>> >> Internet Protocol, Src: 98.244.55.100 (98.244.55.100), Dst:
>>> 173.11.22.111
>>> >> (173.11.22.111)
>>> >> User Datagram Protocol, Src Port: sip (5060), Dst Port: 5090 (5090)
>>> >> Session Initiation Protocol
>>> >> Request-Line: REGISTER sip:173.11.22.111:5090 SIP/2.0
>>> >> Message Header
>>> >> Via: SIP/2.0/UDP 10.1.10.150:5060;branch=z9hG4bK58981045;rport
>>> >> Transport: UDP
>>> >> Sent-by Address: 10.1.10.150
>>> >> Sent-by port: 5060
>>> >> Branch: z9hG4bK58981045
>>> >> RPort: rport
>>> >> From: <sip:8885554547 at 173.11.22.111:5090;user=phone>;tag=138706651
>>> >> To: <sip:8885554547 at 173.11.22.111:5090;user=phone>
>>> >> Call-ID: 1035241259-5060-1 at 10.1.10.150
>>> >> CSeq: 79875 REGISTER
>>> >> Sequence Number: 79875
>>> >> Method: REGISTER
>>> >> Contact:
>>> >> <sip:8885554547 at 10.1.10.150:5060
>>> ;user=phone>;reg-id=1;+sip.instance="<urn:uuid:00000000-0000-1000-8000-000B821F9A84>"
>>> >> Contact Binding:
>>> >> <sip:8885554547 at 10.1.10.150:5060
>>> ;user=phone>;reg-id=1;+sip.instance="<urn:uuid:00000000-0000-1000-8000-000B821F9A84>"
>>> >> Max-Forwards: 70
>>> >> User-Agent: Grandstream HT-503 V1.1B 1.0.1.63
>>> >> Supported: path
>>> >> Expires: 300
>>> >> Allow: INVITE, ACK, OPTIONS, CANCEL, BYE, SUBSCRIBE, NOTIFY, INFO,
>>> REFER,
>>> >> UPDATE
>>> >> Content-Length: 0
>>> >> ___________________________________________________________
>>> >>
>>> >> So, here are my questions:
>>> >>
>>> >> - Why is the Sofia Status so much different for the registration
>>> coming
>>> >> through the pfSense firewall. It looks like it doesn't get tagged as
>>> being
>>> >> NAT'd and the "Contact" info is much less.
>>> >>
>>> >> - Do most modern routers automatically Static Port NAT any SIP
>>> traffic? Both
>>> >> DD-WRT and SMC routers appear to be doing this - and not just on a
>>> simple
>>> >> Port bases (UDP 5060 only), because one of these examples is on 5062.
>>> Are
>>> >> these "SIP aware" firewalls that are doing this automatically, as the
>>> IPCOP
>>> >> did before?
>>> >>
>>> >> - Is the extra "Contact" data in the last packet example different
>>> because
>>> >> it is a different UA (HT-503 rather than an HT-287)
>>> >>
>>> >> - Is Freeswitch not flagging the registration from my office (User4)
>>> as
>>> >> being NAT'd because it is coming in on the same subnet as the
>>> interface
>>> >> Freeswitch received the packet on (Freeswitch is at 173.11.22.111 and
>>> >> pfsense is at 173.11.22.99)?
>>> >>
>>> >> Sorry for this terribly long posting - I'm just very curious to
>>> understand
>>> >> what is going on here, now that I have collected all this information.
>>> >>
>>> >> Thanks,
>>> >>
>>> >> Dave
>>> >>
>>> >>
>>> >>
>>> >
>>> > --
>>> > Sent from my mobile device
>>> >
>>> > ======================
>>> > Tony Graziano, Manager
>>> > Telephone: 434.984.8430
>>> > sip: tgraziano at voice.myitdepartment.net
>>> > Fax: 434.984.8431
>>> >
>>> > Email: tgraziano at myitdepartment.net
>>> >
>>> > LAN/Telephony/Security and Control Systems Helpdesk:
>>> > Telephone: 434.984.8426
>>> > sip: helpdesk at voice.myitdepartment.net
>>> > Fax: 434.984.8427
>>> >
>>> > Helpdesk Contract Customers:
>>> > http://www.myitdepartment.net/gethelp/
>>> >
>>> > Why do mathematicians always confuse Halloween and Christmas?
>>> > Because 31 Oct = 25 Dec.
>>> >
>>>
>>>
>>>
>>> --
>>> ======================
>>> Tony Graziano, Manager
>>> Telephone: 434.984.8430
>>> sip: tgraziano at voice.myitdepartment.net
>>> Fax: 434.984.8431
>>>
>>> Email: tgraziano at myitdepartment.net
>>>
>>> LAN/Telephony/Security and Control Systems Helpdesk:
>>> Telephone: 434.984.8426
>>> sip: helpdesk at voice.myitdepartment.net
>>> Fax: 434.984.8427
>>>
>>> Helpdesk Contract Customers:
>>> http://www.myitdepartment.net/gethelp/
>>>
>>> Why do mathematicians always confuse Halloween and Christmas?
>>> Because 31 Oct = 25 Dec.
>>>
>>> _______________________________________________
>>> FreeSWITCH-users mailing list
>>> FreeSWITCH-users at lists.freeswitch.org
>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>>> http://www.freeswitch.org
>>>
>>> _______________________________________________
>>> FreeSWITCH-users mailing list
>>> FreeSWITCH-users at lists.freeswitch.org
>>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>>> http://www.freeswitch.org
>>>
>>>
>>
>>
>> --
>> ======================
>> Tony Graziano, Manager
>> Telephone: 434.984.8430
>> sip: tgraziano at voice.myitdepartment.net
>> Fax: 434.984.8431
>>
>> Email: tgraziano at myitdepartment.net
>>
>> LAN/Telephony/Security and Control Systems Helpdesk:
>> Telephone: 434.984.8426
>> sip: helpdesk at voice.myitdepartment.net
>> Fax: 434.984.8427
>>
>> Helpdesk Contract Customers:
>> http://www.myitdepartment.net/gethelp/
>>
>> Why do mathematicians always confuse Halloween and Christmas?
>> Because 31 Oct = 25 Dec.
>>
>>
>> _______________________________________________ FreeSWITCH-users mailing
>> list FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-usersUNSUBSCRIBE:
>> http://lists.freeswitch.org/mailman/options/freeswitch-users
>> http://www.freeswitch.org
>>
>> _______________________________________________
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>> http://www.freeswitch.org
>>
>>
>
>
> --
> ======================
> Tony Graziano, Manager
> Telephone: 434.984.8430
> sip: tgraziano at voice.myitdepartment.net
> Fax: 434.984.8431
>
> Email: tgraziano at myitdepartment.net
>
> LAN/Telephony/Security and Control Systems Helpdesk:
> Telephone: 434.984.8426
> sip: helpdesk at voice.myitdepartment.net
> Fax: 434.984.8427
>
> Helpdesk Contract Customers:
> http://www.myitdepartment.net/gethelp/
>
> Why do mathematicians always confuse Halloween and Christmas?
> Because 31 Oct = 25 Dec.
>
>
> _______________________________________________
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
> http://www.freeswitch.org
>
>
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