[AusNOG] Upstream PMTUD broken? Packets blackhole

[Mark Andrews]

In message <CAFXuDfZ5onT0YPNZX24Z73V88Vzyi-k7MVs+mL3yeZCnKCjpgA at mail.gmail.com>
, Cameron Ferdinands writes:

We also need "shouldidropfragments.com" and "shouldihashports.com" with
a similar NO.
 
> http://shouldiblockicmp.com/  share with your friends! Great resource
> 
> Regards,
> 
> On Wed, Sep 14, 2016 at 9:55 AM Mark Newton <newton at atdot.dotat.org> wrote:
> 
> > On Sep 14, 2016, at 12:34 AM, s.s.o.n.i.k+a.u.s.n.o.g at gmail.com wrote:
> >
> > Client firewall MTU set to 1484: Successful reply at length 1456.
> > Unsuccessful at 1457, however echo request is seen, and unreachable 3:4
> > message is returned by firewall, but never arrives at the source.
> >
> >
> > Ethernet firewall? Why is the MTU so low?
> >
> > These problems are virtually always caused by a firewall blocking ICMP.
> > Usually it=E2=80=99s a firewall operated by the person who is complaining=
>  about
> > PMTUD not working :-)
> >
> >   - mark
> >
> >
> > _______________________________________________
> > AusNOG mailing list
> > AusNOG at lists.ausnog.net
> > http://lists.ausnog.net/mailman/listinfo/ausnog
> >
> 
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> <div dir=3D"ltr"><div><a href=3D"http://shouldiblockicmp.com/">http://shoul=
> diblockicmp.com/</a>=C2=A0 share with your friends! Great resource<br></div=
> ><div><br></div><div>Regards,</div><div><br><div class=3D"gmail_quote"><div=
>  dir=3D"ltr">On Wed, Sep 14, 2016 at 9:55 AM Mark Newton <<a href=3D"mai=
> lto:newton at atdot.dotat.org">newton at atdot.dotat.org</a>> wrote:<br></div>=
> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
> x #ccc solid;padding-left:1ex"><div style=3D"word-wrap:break-word">On Sep 1=
> 4, 2016, at 12:34 AM, <a href=3D"mailto:s.s.o.n.i.k+a.u.s.n.o.g at gmail.com" =
> target=3D"_blank">s.s.o.n.i.k+a.u.s.n.o.g at gmail.com</a> wrote:<br></div><di=
> v style=3D"word-wrap:break-word"><div><blockquote type=3D"cite"><span style=
> =3D"font-family:Calibri,sans-serif;font-size:11pt">Client firewall MTU set =
> to 1484: Successful reply at length 1456. Unsuccessful at 1457, however ech=
> o request is seen, and unreachable 3:4 message is returned by firewall, but=
>  never arrives at the source.</span><br></blockquote><div><br></div></div><=
> /div><div style=3D"word-wrap:break-word"><div>Ethernet firewall? Why is the=
>  MTU so low?</div><div><br></div><div>These problems are virtually always c=
> aused by a firewall blocking ICMP. Usually it=E2=80=99s a firewall operated=
>  by the person who is complaining about PMTUD not working :-)</div></div><d=
> iv style=3D"word-wrap:break-word"><div><br></div><div>=C2=A0 - mark</div><d=
> iv><br></div><div><br></div></div>_________________________________________=
> ______<br>
> AusNOG mailing list<br>
> <a href=3D"mailto:AusNOG at lists.ausnog.net" target=3D"_blank">AusNOG at lists.a=
> usnog.net</a><br>
> <a href=3D"http://lists.ausnog.net/mailman/listinfo/ausnog" rel=3D"noreferr=
> er" target=3D"_blank">http://lists.ausnog.net/mailman/listinfo/ausnog</a><b=
> r>
> </blockquote></div></div></div>
> 
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> 
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org