Question about FtpPortMapper and TCPRewriter

[Eddie Kohler]

> 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 sequence number offset may differ for every connection. After all, some
connections are FTP, some aren't, for example.

> 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.

I don't know much about AddressTranslator, but my guess is that you would
need to write a TCPAddressTranslator, analogous to TCPRewriter, that does
sequence number offsetting the same way that TCPRewriter does, but for IPv6
packets.

Eddie