TCP/IP header TOS flag(s) on file sharing networks

Dan Egli ddavidegli at
Sat Aug 24 05:41:57 MDT 2013

Hey guys, anyone know where I can find a complete breakdown on some of the
file sharing protocols? I'm trying to help someone here with configuring
their Linux machine as a router and they want to limit the file sharing
services using traffic shaping. The problem is that we can't simply tell tc
to match the destination port because the port # is randomly generated
during each install of the file sharing client (at least, that's been my
experience. I've personally seen three different ports used on the same
network during different installs). So I figured he could match the TOS
flag which would (I'd think) be the same for the various networks. However,
I don't know what the TOS flag IS for the various file sharing network
protocols, so I'm a bit lost as to how to set this up. Also, if someone has
a better idea on how to limit the various file sharing services to no mare
than X bandwidth across all machines, I'd love to hear it. What he's
explained that he wants is to allow his kids to use file sharing (he has
three kids) each on a separate machine (two are High-school age and have
their own laptops that they hook up via Ethernet at home, one just uses the
family computer), but wants to limit the total bandwidth to 3 megabits. The
problem with using the traffic limits in the program is that if only one of
the kids is logged in to a file sharing network and his client is set to 1
mbit, then that's all he gets. This guy wants three megabits, equally split
between all file sharing traffic currently running through the router. So
if one person is file sharing, they can download 3 mbits. If two are
sharing, they can each only download 1.5 mbits, and of course if all three
are sharing, 1 mbit each.

If someone knows either where to find the TOS flags for the following
networks, or (Even better) what the TOS flags are, or a better way to
accomplish this, I'd appreciate it.

The networks he's said that he's looking to limit are: Kazaa, Gnutella v1
and v2, and eDonkey 2000.

Thanks folks!

--- Dan

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