Re: Strange PPPoe problem
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On Thu, 23 Mar 2006 14:35:20 -0600
anoop aryal <aaryal@foresightint.com> wrote:
> > > On Thursday 23 March 2006 10:58, Jacob S wrote:
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> > > >Howdy list,
> > > >
> > > >I recently changed ISPs, away from static ips on a dsl line to a
> > > > single dynamic ip on Veriz*n's new Fi*S (fiber optic) service.
> > > > The new service uses PPPoe - not a problem, or so I thought - I
> > > > have PPPoe on my firewall.
> > > >
> > > >Now, I have used PPPoe from this very same firewall on a
> > > >different dsl line before and it worked great. But for some
> > > >reason when I do PPPoe for the new fiber line only http traffic
> > > >works properly. When downloading e-mail, everything is fine
> > > >until it tries to download the mail (I see it login, get the
> > > >number of messages to download, and then it tries to start
> > > >downloading). At this point the e-mail just hangs until it
> > > >finally times out. It does not seem to be port-related, as I
> > > >have setup the e-mail server with port-forwarding rules to allow
> > > >me to download mail on non-standard ports and it exhibits the
> > > >same problem. And if I do PPPoe on the provided D-Link router,
> > > >instead of on my firewall, everything (including e-mail) works
> > > >great.
> > > > <snip>
>
> google PMTU to read about this in more detail, but it seriously
> sounds like icmp 3/4 packets are being dropped somewhere. if you
> setup your firewall to allow icmp packets of type 3/4 thru, you
> should be all set (well, you'd hope so anyway). a set of rules like
> so should do the trick:
>
> -A INPUT -p icmp --icmp-type fragmentation-needed -j ACCEPT
> -A OUTPUT -p icmp --icmp-type fragmentation-needed -j ACCEPT
> -A FORWARD -p icmp --icmp-type fragmentation-needed -j ACCEPT
>
> then, make sure you have the iputils-ping package installed (not the
> netkit-ping) and try:
>
> ping your.mail.host -c 1 -M do -s 1472
>
> and you should get back an icmp reply saying what the mtu should be.
> subtract 28 from it and try pinging with that size and it should go
> thru. eg, if the reply says mtu = 1492, try:
>
> ping your.mail.host -c 1 -M do -s 1464
>
> and it should go thru just fine. if you get a request timeout, that
> means that some routers are just dropping your packets without an
> icmp 3/4 message. keep reducing the size of your packet and see if
> you can get anything thru. read up on PMTU for possible solutions.
> there are ways to stop automatic PMTU discovery etc.
Ok, things are getting stranger here.
I ran the iptables rules you suggested and here's the ping results:
# ping longbow.arroway.com -c 1 -M do -s 1472
PING longbow.arroway.com (66.252.129.166) 1472(1500) bytes of data.
- From pool-71-244-52-50.dllstx.fios.verizon.net (71.244.52.50)
icmp_seq=1 Frag needed and DF set (mtu = 1492)
- --- longbow.arroway.com ping statistics ---
0 packets transmitted, 0 received, +1 errors
# ping longbow.arroway.com -c 1 -M do -s 1464
PING longbow.arroway.com (66.252.129.166) 1464(1492) bytes of data.
1472 bytes from longbow.arroway.com (66.252.129.166): icmp_seq=1 ttl=49
time=163 ms
- --- longbow.arroway.com ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 163.150/163.150/163.150/0.000 ms
So then I added the line
pty "/usr/sbin/pppoe -I eth0 -T 80 -m 1464"
to /etc/ppp/peers/dsl-provider, but the problem continued. After
commenting that line back out (so that no pty... -m declaration had
been made in the dsl-provider config), I was able to sucessfully
download one single e-mail from a server. There was only one e-mail in
that account and it downloaded like normal. So I sent an e-mail to that
account, being that it was on a different server from my normal tests,
but that one would not download sucessfully. So it would seem like it
had something to do with the size and speed of the one that downloaded
properly.
In short, it's still a no go and I have no clue why. The D-Link router
still works great, but pppoe from the firewall doesn't.
Any more clues or suggestions, anyone?
TIA,
Jacob
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