Hamish Whittal <hamish(_at_)QEDux(_dot_)co(_dot_)za>:
I have some mail, with large attachments I need to get from my ISP. When
fetchmail is in foreground mode (i.e. fetchmail -v from the command
line) then the mail gets downloaded fine. However, I need to kick off a
cron job ot fetch this stuff ever half hour so I have a script that will
run this command from the script (exactly the same as the command line).
I have showdots=on for the purpose of checking the progress of the mail.
In CLM (cmd line mode), the mail gets fetched fine. In CRON mode, the
large mails keep the link up, but no data gets transferred after +- 360k
(364544bytes exactly). I have done a tcpdump on ppp0 and found that
after this 'limit' the tcp window size drops to 0, despite my ISP
machine trying to negotiate a larger one (approx 8253). I have:
Upgraded to the latest? 5.9.3 of fetchmail,
Changed hardware (modem and machine),
Changed from POP to IMAP,
Changed OS's from SuSE to RedHat,
Installed the latest kernel I could find (2.4.10),
It seem that my side does the negotiating DOWN of the tcp window size
after the 360K limit is reached. Small mails, no problem. Large ones get
things in a knot. Another odditiy, is that for these larger mails no
'showdots' as shown. Progress is monitored by looking at sendmail Q.
Wow. This sounds like it might be a bad bug in Linux's TCP/IP support.
I don't often do this, but I think I have to recommend that you post
this bug report to the Linux kernel mailing list.
--
<a href="http://www.tuxedo.org/~esr/";>Eric S. Raymond</a>
When all government ...in little as in great things... shall be drawn to
Washington as the center of all power; it will render powerless the checks
provided of one government on another, and will become as venal and oppressive
as the government from which we separated." -- Thomas Jefferson, 1821