http://i2p-javadocs.i2p/net/i2p/client/streaming/impl/PcapWriter.html
We don't, however, convert I2P-style sequence numbers, which count packets,
to TCP-style byte counts. We don't track a lowest-acked-thru byte count atm, really.
We do represent the window size in bytes though, so that's real confusing.
This is designed to debug the streaming lib, but there are not log calls for every
single packet - pings and pongs, and various odd cases where received packets
are dropped, are not logged.