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Date: Tue, 14 Jan 2014 14:33:23 +0400
From: Gleb Smirnoff <glebius@FreeBSD.org>
To: Dennis Yusupoff <dyr@smartspb.net>
Subject: Re: Set UDP packet size in ng_netflow/ng_ksocket?
Message-ID: <20140114103323.GS8472@FreeBSD.org>
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On Tue, Jan 14, 2014 at 02:28:35PM +0400, Dennis Yusupoff wrote:
D> Are there any way to set UDP packet size generated from ng_netflow with
D> ng_ksocket?
D> I'm sending netflow UDP packets throught tunnel with MTU 1476 and it's
D> disappointing to see fragmented packets on it as far as it could be a
D> problem for some firewalls, because ng_ksocket always generate
D> 1500-bytes packets. Or I'm wrong?

The ng_ksocket is irrelevant here. This is ng_netflow, who decides on
datagram size. AFAIR, the size of Netflow datagram is dictated by the Cisco
Netflow, and full sized datagram fits into 1500 MTU. Probably it was designed
to be used on 1500 MTU sized networks.

You can hack sources and redefine NETFLOW_V1_MAX_RECORDS or NETFLOW_V5_MAX_RECORDS
so that datagram would fit your link.

-- 
Totus tuus, Glebius.