Subject: Limiting the size of incoming/outgoing TCP packets

From: Cheng Jack-QA3581 <[email-masked]>
Date: Fri, 1 Mar 2002 10:35:47 -0600

Hi,

I'm interested in limiting the size of incoming/outgoing TCP packets without
affecting 
incoming/outgoing UDP packets.  

Here's the scenario ...

Say that Host1 establishes a TCP connection with Host2.  Host1 advertises a
Maximum 
Segment Size (MSS) option in the SYN (or SYN ACK).  This tells Host2 the
maximum
size of TCP packets that Host1 can handle.  So this limits the packet size
on the *incoming*
TCP packets on Host1.  How can Host1's advertised MSS be set to a lower
value?  Has
anyone ever implemented this?

Also, I want to limit the size of *outgoing* TCP packets from Host1 to
Host2?  One way is to 
change the advertised MSS that Host2 sends to the desired value.  I don't
want to do that though
since Host2 sends/receives TCP packets from other hosts and doing so will
affect these other hosts.

Thanks for the help.

	- Jack

---

From: Alan Cox <[email-masked]>
Date: Fri, 1 Mar 2002 18:10:40 +0000 (GMT)

> on the *incoming* TCP packets on Host1.  How can Host1's advertised MSS be 
> set to a lower value?  Has anyone ever implemented this?

Linux supports setting MSS per route. Its a handy way of dealing with all
the overpaid clueless security consultants who can't configure firewalls
to handle icmp must fragment.

The window is also route configurable

Alan