Question about FtpPortMapper and TCPRewriter

[Juan Luis Baptiste]

Hi,

FtpPortMapper uses a TCPRewriter element to recalculate the  new secuence numbers after the tranlation of the content of the ftp packet, like this:

ftpportmapper.cc, line 337:

IPFlowID p_flow(p);
if (TCPRewriter::TCPMapping *p_mapping = _control_rewriter->get_mapping(IP_PROTO_TCP, p_flow)) {

...
}

First of all, I don't quite understand very well how the tcprewirter element calculates the new seq. numbers, why it needs to find the corresponding mapping to the flow id of the packet being translated?

The problem I have is that my element (ftpportmapper6) is for use with addressTranslator and protocolTranslators(64-46), and there's no IPRewriter elements from where TCPRewriter can get the mappings, because addressTranslator element is the one in charge of managing the mapping tables and TCPRewriter uses IPRewriter to lookup the mapping tables (right?). So I don't know what to do here to calculate the seq numbers using addressTarnslator and TCPRewriter. I hope I made my self clear with this.

Can anybody give me a hint on how to do this? Eddie? :-)


Juan Luis
-- 

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