Skip site navigation (1)Skip section navigation (2)
Date:      Wed, 29 Oct 2003 16:22:29 -0000
From:      "Company 2210" <company2210@hotmail.com>
To:        <freebsd-net@freebsd.org>
Subject:   Re: ipsec tunnels & packet length issues
Message-ID:  <Law12-OE47hIIqgRXrJ0000d843@hotmail.com>
References:  <200310290904.KAA09027@galaxy.hbg.de.ao-srv.com>

next in thread | previous in thread | raw e-mail | index | archive | help

So, what would be a suitable MTU value for an ESP encrypted packet using
Blowfish?

Thanks

----- Original Message -----
From: "Helge Oldach" <helge.oldach@atosorigin.com>
To: "Eric Masson" <e-masson@kisoft-services.com>
Cc: <freebsd-net@freebsd.org>
Sent: Wednesday, October 29, 2003 9:04 AM
Subject: Re: ipsec tunnels & packet length issues


> Eric Masson:
> >>>>>> "Michael" == Michael Sierchio <kudzu@tenebras.com> writes:
> >
> > Michael> You should allow for an IP header with options and the ESP
> > Michael> header, which is smaller than 1450. For SKIP I use 1366 as the
> > Michael> advertised MTU, and for IPsec usually 1436, unless I need to
> > Michael> accomodate ESP and AH, in which case it's smaller.
> >
> >Ok, that's fine.
> >
> > Michael> It's a known feature of any sort of IP encapsulation.
> >
> >I understand.
> >
> >I'm no kernel hacker at all, I was just thinking about the ability for
> >the tunnel endpoint to send back an icmp packet type 3 code 4 when the
> >packet is too long to be encapsulated.
>
> Actually this is the case. Or better, it *should* be happening - I don't
> know if you see the ICMPs or not. Note that this must be done on the
> local tunnel endpoint, not the remote one.
>
> Helge
> _______________________________________________
> freebsd-net@freebsd.org mailing list
> http://lists.freebsd.org/mailman/listinfo/freebsd-net
> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?Law12-OE47hIIqgRXrJ0000d843>