Thanks for the detailed explanation, slowly i understand the flags :-)

Klaus

-----Original Message----- From: Jan Janak [mailto:jan@iptel.org] Sent: Wed 10.12.2003 23:50 To: Klaus Darilion Cc: serusers@lists.iptel.org Subject: Re: [Serusers] nathelper question - nat_flag Basically usrloc has been extended to save the status of a flag. Which flag it should save can be configured using the "nat_flag" parameter of the registrar module.

Let's say you configure modparam("registrar", "nat_flag", 6)

Then flag 6 will be saved into the user location database each time you call save("location") and retrieved each time you call lookup("location").

If flag 6 is set before save() then it will be also set after lookup() for the same contact.

Because the user location database stores already rewritten contact (in case the user agent was behind a NAT), you don't know if the contact returned by lookup() is behind NAT

That's what the flag is for. If the configured flag is set after lookup("location") then you know that the contact is behind NAT.

Typically you would do something like this (very rough example):

# For REGISTER If (contact_is_behind_nat) { rewrite_contact setflag(6) save("location") }

# For INVITE if (lookup("location")) { if (isset(6)) { # Contact is behind NAT force_rtp_proxy } }

Jan.

On 10-12 23:40, Klaus Darilion wrote:

Hi!

I'm lost in the NAT problem!

I read about the 'new' flags which will be stored in the location table to detect the presence of NATed clients. http://lists.iptel.org/pipermail/serdev/2003-October/000690.html

But I can't find any documentation about them. How do I use them? Do I have to use setflag(?) before save("location")? Which flag do I have to set? Do I have to retrive the flags during lookup("location") to force_rtp_proxy in case of an registered client whic is nated?

regards, Klaus

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