Subject: [Sip] CallId question

From: Anil Bollineni <[email-masked]>
Date: Tue, 10 Feb 2004 12:27:23 -0800

Hello,

            I have a question about CallId. Suppose two UA's generate
callid's putting theire hostnames and send to firewall/NAT.

            UA1:INVITE

                  CallID: [email-masked] <mailto:[email-masked]> 

            UA2: INVITE

                     CallId: [email-masked] <mailto:[email-masked]> 

            Because those callid information contain IP addresses, the
firewall/NAT should translate these IP addresses by putting it's own IP in
callId. The callId's are changed to call1@firewall_ip, call1@firewall_ip.
When responses come back from their respective UAS's the firewall/NAT
translates the it's IP address in callId's to their original IP's. My
question is should I change the string "call1" to something generated by
firewall or Is it OK to leave like that. Even though they have same CallId,
the proxy should discriminate the calls by from-tag, callid, and to-tag.

According to Spec, any UA should have a different means of generating
callid's with those of other UA's. 

Anything to do correctly to the above procedure?

Thanks in advance,

Anil

This email contains material that is confidential. The content of this email
is for the sole use of the intended recipient(s). Any review or distribution
by persons other than the intended recipient(s) without the express
permission of NetScreen Technologies, Inc. is strictly prohibited. If you
are not the intended recipient, please contact the sender and delete/destroy
all copies of this email and any related attachments. NetScreen does not
guarantee the accuracy or completeness of third party materials or
information.

---

From: "Christian Stredicke" <[email-masked]>
Date: Tue, 10 Feb 2004 22:15:00 +0100

:-) That's the reason why we started to AVOID IP addresses in the call ID!!!

Well I guess the firewall which is changing the Call-ID is a half-way
implementation of an application layer firewall. What it is doing is simply
junk and it's a miracle if it's working with any SIP compliant devices.

The "call1" part should be significantly random to avoid using the same
call-ID. That's why most of the user agents chose a call ID that is
random-generated.

Christian

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of Anil
Bollineni
Sent: Tuesday, February 10, 2004 9:27 PM
To: [email-masked]'
Subject: [Sip] CallId question

Hello,

            UA1:INVITE

                  CallID: [email-masked]

            UA2: INVITE

                     CallId: [email-masked]

Thanks in advance,

Anil

---

From: Cullen Jennings <[email-masked]>
Date: Tue, 10 Feb 2004 15:34:06 -0800

The NAT/FW must not go changing this stuff. If it does, a S/MIME signed
sipfrag will fail. There is no need for the NAT to go change call IDs

On 2/10/04 12:27 PM, "Anil Bollineni" <[email-masked]> wrote:

> Hello,
>  
>             I have a question about CallId. Suppose two UA's generate callid's
> putting theire hostnames and send to firewall/NAT.
>             UA1:INVITE
> callId. The callId's are changed to call1@firewall_ip, call1@firewall_ip. When
> responses come back from their respective UAS's the firewall/NAT translates
> the it's IP address in callId's to their original IP's. My question is should
> I change the string "call1" to something generated by firewall or Is it OK to
> leave like that. Even though they have same CallId, the proxy should
> discriminate the calls by from-tag, callid, and to-tag.
> According to Spec, any UA should have a different means of generating callid's
> with those of other UA's.
>  
> by persons other than the intended recipient(s) without the express permission
> of NetScreen Technologies, Inc. is strictly prohibited. If you are not the
> intended recipient, please contact the sender and delete/destroy all copies of
> this email and any related attachments. NetScreen does not guarantee the
> accuracy or completeness of third party materials or information.
> 
>  
>

---

From: Thomas Froment <[email-masked]>
Date: Wed, 11 Feb 2004 16:07:28 +0100

Cullen Jennings wrote:

>
> The NAT/FW must not go changing this stuff. If it does, a S/MIME 
> signed sipfrag will fail. There is no need for the NAT to go change 
> call IDs

Yes, NAT does not change the content of SIP messages (Call-ID, 
Via-Header, or SDP content...), since it maps IP/ports at the transport 
level (TCP/UDP...). That's even why it is necessary to use additional  
functions (STUN/TURN and more..) to make SIP work with NAT...

>                 I have a question about CallId. Suppose two UA's
>     generate callid's putting theire hostnames and send to firewall/NAT.
>                 UA1:INVITE
>                 Because those callid information contain IP addresses,
>     the firewall/NAT should translate these IP addresses by putting
>     it's own IP in callId. The callId's are changed to
>     call1@firewall_ip, call1@firewall_ip. When responses come back
>     from their respective UAS's the firewall/NAT translates the it's
>     IP address in callId's to their original IP's. My question is
>     should I change the string "call1" to something generated by
>     firewall or Is it OK to leave like that. Even though they have
>     same CallId, the proxy should discriminate the calls by from-tag,
>     callid, and to-tag.
>     According to Spec, any UA should have a different means of
>     generating callid's with those of other UA's.
>      

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip