Dave,

I misread your mail the first time and did not see you sent traces.

I think there are some interesting things in those.

For the packet coming from your HT-287 without the static port NAT:
Via: SIP/2.0/UDP 10.8.11.149:5062;branch=z9hG4bKda48f838c8689e41
-> rport is missing

For the packet coming from the one behind a DD-WRT:
rport is missing too, but the source port in the Via matches the source port of the packet, so it works, the same way it works with your pfSense if you add the static port NAT.
But why FS manages to guess it's behind NAT eludes me, but the NAT detecting algo in FS is clearly complex.

For the packet coming from the HT-503:
I think you made a mistake. You said at the beginning of your mail that it is behind DD-WRT, but before the trace, you say "one more packet coming from Comcast/SMC".
Anyway, this one is interesting.
rport is there, so HT-503 is rport-capable (but HT-287 is not).
I would check if a configuration or a firmware upgrade could enable rport on the HT-287.

Also, you wonder if modern routers have some automatic static NAT.
Actually, no, but what they do quite often is to not change the source port of the packet if this port is available on the external interface.
For instance, if your device sends a packet from port 5060, and this port is free on the external side of the router, it will preserve 5060.
Then if a second device sends a packet from port 5060, as it is already used, it will use a random port.
You end up having a pseudo static NAT behaviour for the first device on your network.
I saw that on business routers from Draytek, Funkwerk and others.
So perhaps your ipcop was doing that ?
Wild guess: if you add a second phone with the same source port 5060 behind a DD-WRT router, I am pretty sure you will have issues with its registration.

About your question "is FreeSWITCH not tagging the device as behind nat because it is on the same subnet as pfSense ?".
That's quite possible.
I think there are places in FS conf where you define what is local. I think it's the special keyword localnet.auto.

But I really think the end of all isues is rport.
If rport is not available on your device, you can still force rport on FS side:
<param name="NDLB-force-rport" value="true"/>

David Ponzone  Direction Technique
tel:      01 74 03 18 97
gsm:   06 66 98 76 34

Service Client IPeva
tel:      0811 46 26 26

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Le 29/08/2010 à 09:01, Dave Redmore a écrit :

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@192.168.1.137
User:           8885554525@173.11.22.111
Contact:        "user" <sip:8885554525@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@173.11.22.111

Call-ID:        1716488819-5062-1@192.168.7.150
User:           8885554544@173.11.22.111
Contact:        "user" <sip:8885554544@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@173.11.22.111

Call-ID:        090ee80e1a0ec9ed@10.8.11.149
User:           8885554549@173.11.22.111
Contact:        "user" <sip:8885554549@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@173.11.22.111

Call-ID:        1035241259-5060-1@10.1.10.150
User:           8885554547@173.11.22.111
Contact:        "user" <sip:8885554547@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@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@173.11.22.111:5090>;tag=c8a0d452edc5ac4b
            SIP from address: sip:8885554549@173.11.22.111:5090
            SIP tag: c8a0d452edc5ac4b
        To: <sip:8885554549@173.11.22.111:5090>
        Contact: <sip:88855564549@10.8.11.149:5062>
            Contact Binding: <sip:8885554549@10.8.11.149:5062>
        Supported: replaces, timer
        Call-ID: aa77d777bae71be6@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@173.11.22.111:5090>;tag=8dc68b35111c4261
        To: <sip:8156564525@173.15.28.101:5090>
        Contact: <sip:8885554525@192.168.1.137>
            Contact Binding: <sip:8885554525@192.168.1.137>
        Call-ID: 0e551b3c694a793c@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@173.11.22.111:5090;user=phone>;tag=138706651
        To: <sip:8885554547@173.11.22.111:5090;user=phone>
        Call-ID: 1035241259-5060-1@10.1.10.150
        CSeq: 79875 REGISTER
            Sequence Number: 79875
            Method: REGISTER
        Contact: <sip:8885554547@10.1.10.150:5060;user=phone>;reg-id=1;+sip.instance="<urn:uuid:00000000-0000-1000-8000-000B821F9A84>"
            Contact Binding: <sip:8885554547@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

 
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