Dominik George:
> I am running Postfix on my local machine and it passes on mail to a
> smarthost to which it is connected through a very non-optimal
> connection.
>
> Sending a mail with a PDF attachment of 3 MiB regularly takes up to 30
> minutes.
That's similar to my (backup) dialup connection, not too long ago.
> Is there a way to trace how much of a message body has been transferred
> to the next hop?
There is no progress bar :-)
However, tcpdump will report byte offsets relative to the beginning
of a TCP connection, or if the connection exists before you start
tcpdump, relative to the first packet that tcpdump sees.
With some tcpdump versions this can be as simple as:
# tcpdump -ni name-of-inteface-here host foo and port 25
...
09:11:38.945152 IP 192.168.0.2.smtp > 192.168.1.2.57601: Flags [P.],
seq 49:97, ack 96, win 8326, options [nop,nop,TS val 1896616435 ecr
1425166], length 48
...
This shows bytes 49-98 being sent.
Wietse
