PPPoE and troubles with TCP
rost...@yahoo.com
I have Alcatel Speedtouch Home ADSL modem. I use PPPoE protocol for
connection with my Internet Service Provider (ISP) through this ADSL
modem. I use FreeBSD 4.7-RELEASE and ppp (a.k.a. user-ppp) for this. In
the /etc/ppp/ppp.conf file I have ' set MRU 1492' and ' set MTU 1492'
options. This is because the maximum MTU one can use with PPPoE is 1492
according to RFC 2516. I have no problems with "dialing" to my ISP. But
after the PPPoE connection is established I have troubles with TCP
connections to some hosts. For example I can't go to
hhtp://www.ssh.com/ but to http://www.freebsd.org/ or
http://www.gnu.org/ I can. If I run 'telnet www.ssh.com 80' and enter
HTTP request according to HTTP 1.1 or 1.0 protocol I don't get any
answer. If I enter just 'GET /' I get some short answer. 'GET /' is an
HTTP request according to the old HTTP 0.9 version of the protocol and
it is rarely used today. But the problem is not HTTP, I think. If I do
HTTP request according to HTTP 1.1 from my friends' computer I do have
some long answer. Furthermore if I change the MRU and MTU to 1484 or
smaller I have no problem with www.ssh.com. So it looks like TCP packet
overflow or something like that.
Besides FreeBSD I have Windows 98 Second Edition in my computer. I use
PPPoE with Win98SE too. I use RASPPPOE driver fo it, go to
http://www.raspppoe.com/ for more information. I have no problems with
www.ssh.com when I use Win98SE with this impimentation of PPPoE
protocol. I have MTU == 1492 set by default in RASPPPOE. I don't get
error messages about fragmentation when I run 'ping -f -l 1464
www.ssh.com' in my Win98SE (ICMP+IP=1464+28=1492). Why in FreeBSD I
cannot use MTU == 1492 without problems with some hosts like
www.ssh.com ? How to fix it in FreeBSD?
P.S. ping have different syntax in Windows, so don't be wondered about
-f flag. -f sets "no fragmentation" flag in IP headers of all outgoing packets.
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sta...@vickiandstacey.com
I use ADSL here on my site, but not that modem. How do you connect to
that device from the FBSD box?
Regards,
Stacey
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Stacey Roberts
B.Sc (HONS) Computer Science
rost...@yahoo.com
I configured my ADSL modem to work with PPPoE. Then I changed the
/etc/ppp/ppp.conf file to this one:
==== /etc/ppp/ppp.conf ====
default:
set log Phase Chat LCP IPCP CCP tun command
ident user-ppp VERSION (built COMPILATIONDATE)
set device PPPoE:ed0
set speed sync
# set MRU 1484
# set MTU 1484
set MRU maximum 1492
set MTU maximum 1492
set timeout 0
set urgent none # no priorities
enable dns # request DNS info (for
resolv.conf)
disable ipv6 ipv6cp
disable shortseq protocomp acfcomp vjcomp deflate pred1
mppe
deny shortseq protocomp acfcomp vjcomp deflate pred1
mppe
myisp:
set authname username@ISPstring
set authkey password
add default HISADDR # Add a (sticky) default route
==== /etc/ppp/ppp.conf ====
The hostname of my box can be resolved through /ets/hosts , so I don't
need any kind of 'set ifaddr' in /etc/ppp/ppp.conf file. ed0 is the
ethernet NIC my ADSL modem is connected to.
Many lines of the "default:" section of the ppp.conf file are not critical.
The only ones you need are these:
set device PPPoE:ed0
set MRU maximum 1492
set MTU maximum 1492
enable dns
See `man 8 ppp` for more information.
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sta...@vickiandstacey.com
Dude,
I wasn't asking for assistance.., rather I was hoping to provide
some help in response to your post.. :-)
The reason why I asked about how you connect to your ADSL modem is
because if its ethernet, then there is no need to use ppp.
But if there's a case-requirement why you need to use ppp, then fair
enough.
Let me know either way, okay?
Regards,
Stacey
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Stacey Roberts
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rost...@yahoo.com
Yes, my computer is connected to my ADSL modem by Ethernet.
What is the way to connect with the ISP without PPP?
Is it ethernet bridging with DHCP? My ADSL Service Provider (Bezeq)
does not support this. Moreover, the use of ethernet bridging is
inconvenient for me because I can't switch the ISP by myself.
When I use PPP, over Ethernet or over whatever else, I have ISP string,
so it is very easy to switch the ISP I'd like to use at the moment.
P.S. What about my main question?
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> <snipped>
> > > Many lines of the "default:" section of the ppp.conf file are not
> > critical.
> > > The only ones you need are these:
> > >
> > > set device PPPoE:ed0
> > > set MRU maximum 1492
> > > set MTU maximum 1492
> > > enable dns
> > >
> > > See `man 8 ppp` for more information.
> > >
> >
> > Dude,
> > I wasn't asking for assistance.., rather I was hoping to provide
> > some help in response to your post.. :-)
> >
> > The reason why I asked about how you connect to your ADSL modem is
> > because if its ethernet, then there is no need to use ppp.
> >
> > But if there's a case-requirement why you need to use ppp, then fair
> > enough.
> >
> > Let me know either way, okay?
>
> Yes, my computer is connected to my ADSL modem by Ethernet.
> What is the way to connect with the ISP without PPP?
> Is it ethernet bridging with DHCP? My ADSL Service Provider (Bezeq)
> does not support this. Moreover, the use of ethernet bridging is
> inconvenient for me because I can't switch the ISP by myself.
> When I use PPP, over Ethernet or over whatever else, I have ISP string,
> so it is very easy to switch the ISP I'd like to use at the moment.
>
> P.S. What about my main question?
>
Hi,
I didn't really have to configure *anything* as such to establish
connectivity on FreeBSD. The router I have holds the configurations
requried in order to authenticate to the ISP's upstream router.
All I have to do from FreeBSD's view is configure the external interface
to use the router as the default route (using ifconfig or
/stand/sysinstall). That's it.
As your initial problems, what happens if you set mtu to 1500 (or *not*
define this?)? Here's what man ppp says:
set mtu [max[imum]] [value]
The default MTU is 1500. At negotiation time, ppp will
accept
whatever MRU the peer requests (assuming it's not less than
296
bytes or greater than the assigned maximum). If the MTU is
set,
ppp will not accept MRU values less than value. When
negotia-
tions are complete, the MTU is used when writing to the
inter-
face, even if the peer requested a higher value MRU. This
can be
useful for limiting your packet size (giving better
bandwidth
sharing at the expense of more header data).
If the ``maximum'' keyword is used, ppp will refuse to
negotiate
a higher value. The maximum MTU can be set to 2048 at
most.
If no value is given, 1500, or whatever the peer asks for
is
used. A value must be given when ``maximum'' is specified.
What does ifconfig ed0 return? Please post that output here.
Regards,
Stacey
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--
Stacey Roberts
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sten.dani...@wan.no
Have you remembered to setup anything to fix the MSS in TCP packets =
going through?
You have disabled encryption and compression right?
-----Original Message-----
From: Rostislav Krasny [mailto:rost...@yahoo.com]=20
Sent: 26. desember 2002 15:42
To: sta...@vickiandstacey.com
Cc: freeb...@freebsd.org; FreeBSD Questions
Subject: Re: PPPoE and troubles with TCP
--- Stacey Roberts <sta...@vickiandstacey.com> wrote:
> On Thu, 2002-12-26 at 13:16, Rostislav Krasny wrote:
> > --- Stacey Roberts <sta...@vickiandstacey.com> wrote:
> > > On Thu, 2002-12-26 at 12:26, Rostislav Krasny wrote:
> > > > Hello
> > > >=20
> > > > I have Alcatel Speedtouch Home ADSL modem. I use PPPoE protocol=20
> > > > for connection with my Internet Service Provider (ISP) through=20
> > > > this
> ADSL
> > > > modem. I use FreeBSD 4.7-RELEASE and ppp (a.k.a. user-ppp) for
> this. In
> > > > the /etc/ppp/ppp.conf file I have ' set MRU 1492' and ' set MTU
> 1492'
> > > > options. This is because the maximum MTU one can use with PPPoE=20
> > > > is
> 1492
> > > > according to RFC 2516. I have no problems with "dialing" to my=20
> > > > ISP.
> But
> > > > after the PPPoE connection is established I have troubles with=20
> > > > TCP connections to some hosts. For example I can't go to=20
> > > > hhtp://www.ssh.com/ but to http://www.freebsd.org/ or=20
> > > > http://www.gnu.org/ I can. If I run 'telnet www.ssh.com 80' and
> enter
> > > > HTTP request according to HTTP 1.1 or 1.0 protocol I don't get=20
> > > > any answer. If I enter just 'GET /' I get some short answer.=20
> > > > 'GET /' is
> an
> > > > HTTP request according to the old HTTP 0.9 version of the=20
> > > > protocol
> and
> > > > it is rarely used today. But the problem is not HTTP, I think.=20
> > > > If I
> do
> > > > HTTP request according to HTTP 1.1 from my friends' computer I=20
> > > > do
> have
> > > > some long answer. Furthermore if I change the MRU and MTU to=20
> > > > 1484
> or
> > > > smaller I have no problem with www.ssh.com. So it looks like TCP
> packet
> > > > overflow or something like that.
> > > > Besides FreeBSD I have Windows 98 Second Edition in my computer. =
> > > > I
> use
> > > > PPPoE with Win98SE too. I use RASPPPOE driver fo it, go to=20
> > > > http://www.raspppoe.com/ for more information. I have no=20
> > > > problems
> with
> > > > www.ssh.com when I use Win98SE with this impimentation of PPPoE=20
> > > > protocol. I have MTU =3D=3D 1492 set by default in RASPPPOE. I =
don't
> get
> > > > error messages about fragmentation when I run 'ping -f -l 1464=20
> > > > www.ssh.com' in my Win98SE (ICMP+IP=3D1464+28=3D1492). Why in=20
> > > > FreeBSD I cannot use MTU =3D=3D 1492 without problems with some=20
> > > > hosts like www.ssh.com ? How to fix it in FreeBSD?
> > > >=20
> > > > P.S. ping have different syntax in Windows, so don't be wondered
> about
> > > > -f flag. -f sets "no fragmentation" flag in IP headers of all
> outgoing
> > > > packets.
> > >=20
> > > I use ADSL here on my site, but not that modem. How do you connect =
> > > to that device from the FBSD box?
> >=20
> > I configured my ADSL modem to work with PPPoE. Then I changed the=20
> > /etc/ppp/ppp.conf file to this one:
> >=20
> > =3D=3D=3D=3D /etc/ppp/ppp.conf =3D=3D=3D=3D
> > default:
> > set log Phase Chat LCP IPCP CCP tun command
> > ident user-ppp VERSION (built COMPILATIONDATE)
> >=20
> > set device PPPoE:ed0
> > set speed sync
> > # set MRU 1484
> > # set MTU 1484
> > set MRU maximum 1492
> > set MTU maximum 1492
> > set timeout 0
> > set urgent none # no priorities
> > enable dns # request DNS info (for
> > resolv.conf)
> > disable ipv6 ipv6cp
> > disable shortseq protocomp acfcomp vjcomp deflate =
pred1
> > mppe
> > deny shortseq protocomp acfcomp vjcomp deflate =
pred1
> > mppe
> >=20
> > myisp:
> > set authname username@ISPstring
> > set authkey password
> > add default HISADDR # Add a (sticky) default =
route
> > =3D=3D=3D=3D /etc/ppp/ppp.conf =3D=3D=3D=3D
> >=20
> > The hostname of my box can be resolved through /ets/hosts , so I=20
> > don't need any kind of 'set ifaddr' in /etc/ppp/ppp.conf file. ed0=20
> > is the ethernet NIC my ADSL modem is connected to.
> >=20
> > Many lines of the "default:" section of the ppp.conf file are not
> critical.
> > The only ones you need are these:
> >=20
> > set device PPPoE:ed0
> > set MRU maximum 1492
> > set MTU maximum 1492
> > enable dns
> >=20
> > See `man 8 ppp` for more information.
> >=20
>=20
> Dude,
> I wasn't asking for assistance.., rather I was hoping to provide=20
> some help in response to your post.. :-)
>=20
> The reason why I asked about how you connect to your ADSL modem is=20
> because if its ethernet, then there is no need to use ppp.
>=20
> But if there's a case-requirement why you need to use ppp, then fair=20
> enough.
>=20
> Let me know either way, okay?
Yes, my computer is connected to my ADSL modem by Ethernet. What is the =
way to connect with the ISP without PPP? Is it ethernet bridging with =
DHCP? My ADSL Service Provider (Bezeq) does not support this. Moreover, =
the use of ethernet bridging is inconvenient for me because I can't =
switch the ISP by myself. When I use PPP, over Ethernet or over whatever =
else, I have ISP string, so it is very easy to switch the ISP I'd like =
to use at the moment.
P.S. What about my main question?
__________________________________________________
Do you Yahoo!?
Yahoo! Mail Plus - Powerful. Affordable. Sign up now. =
http://mailplus.yahoo.com
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rost...@yahoo.com
So, your FreeBSD box is within your LAN and have do dial with ADSL at all,
only your router have. Your box have internal LAN's IP 192.168.1.8 and
your router configured to do network address and port translation.
This network configuration is completely different from my one.
I have a modem, not a router.
This is a copy/paste of just 'ifconfig', so you can see all the interfaces:
ed0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet6 fe80::200:21ff:fe82:2503%ed0 prefixlen 64 scopeid 0x1
ether 00:00:21:82:25:03
faith0: flags=8002<BROADCAST,MULTICAST> mtu 1500
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
inet 127.0.0.1 netmask 0xff000000
ppp0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1492
inet 192.117.108.59 --> 192.117.122.11 netmask 0xffffffff
Opened by PID 142
I don't use ed0 directly, ppp use it for ppp0. ed0 is like /dev/cuaa1
when you have regular modem, 33600bps one for example. I use tun0 that
support TCP/IP and have MTU == 1492. Read RFC 2516 for information about
the maximum MTU that is correct with PPPoE protocol. 1492 is the maximum.
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rost...@yahoo.com
>
> Have you remembered to setup anything to fix the MSS in TCP packets
RASPPPOE in my Win98SE have such option enabled by default. It's described
there to solve problem with ICS (Internet Connection Sharing). I don't see
any difference when it is disabled or enabled. RASPPPOE works just good
with MTU == 1492 in my Win98SE. However my FreeBSD in the same box have
troubles with TCP when I use PPPoE with MTU == 1492.
The configuration of TCP MSS in my FreeBSD is default, I didn't change it.
> You have disabled encryption and compression right?
Yes, all types of compression and encryption are disabled, see my previous
post with /etc/ppp/ppp.conf there.
P.S. PPPoE use 8 bytes in each ethernet packet this is the reason why 1492
is the maximum MTU with PPPoE. I found that MTU == 1484 solve my problem,
read my previous posts. But, 1484 = 1492 - 8 ! It looks like double PPPoE
usage or lack of correspondence to the standard of PPPoE protocol
described in RFC 2516.
Maybe PPPoE implementation in FreeBSD have a bug?
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g...@gbch.net
watch these things.]
Rostislav Krasny wrote:
| Maybe PPPoE implementation in FreeBSD have a bug?
The data you have provided is inadequate. The following
/etc/ppp.conf (edited to hide passwords, etc) works with the
version of ppp that has been out since March with an Alcatel
Speed Touch Home ADSL modem on the web sites you had trouble
with:
set device PPPoE:xl0
set authname foo
set authkey bar
set speed sync
enable lqr
set cd 5
set dial
set login
set redial 0 0
set ifaddr 987.654.321.0 0.0.0.0/0
add default HISADDR
set timeout 0
Note that it does not specify anything for MRU and MTU as these
are both handled automatically by ppp now.
Greg
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rost...@yahoo.com
Edited to hide 'authname' and 'authkey' only? What about 'set ifaddr'
line? Did you use this version of /etc/ppp/ppp.conf by yourself?
In my system it produce the following error message:
Working in background mode
Using interface: tun0
Warning: ncprange_aton: 987.654.321.0: Bad address
Warning: set ifaddr: Failed 1
Child failed (errdead)
Ok, after I fixed the problem with 'set ifaddr' I have exactly the same
connection like I had before. You're right, MTU and MRU are both
handled automatically but what the difference it makes in my case?
I still cannot browse http://www.ssh.com/ Can you?
Or could you do some simple test? Just run 'telnet www.ssh.com 80'
and when you're connected enter this HTTP request:
===== HTTP request =====
GET / HTTP/1.1
Host: www.ssh.com
Connection: close
===== HTTP request =====
In the end of 3rd line press Enter twice. Do you get any answer?
I don't. If you get something, maybe you use proxy or your ISP
(Internet Service Provider) have transparent proxy?
Anyway, how could you explain that with MTU == MRU == 1484
I have no problem with www.ssh.com ? How could you explain that
RASPPPOE works good with MTU == 1492 in Win98SE in the same system
and with the same ADSL modem?
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Ge...@bomgardner.net
Here's my ppp.conf - the 10.0.0.1/0 10.0.0.2/0 255.255.255.0
0.0.0.0 are the actual values used in the file. They bear no
relation to any IP addresses used in my network whatsoever. Why
they work; the /0 says there are no significant bits. PPP is free to
change to any required ip. The nat enable is used because the
machine is used as a gateway. I've never had any trouble with this
setup on any web site or any other operation. By the way, this conf
file is used on a 4.5 system. The set MRU 1492 and set MTU
1492 were required because of the way verizon was set up. Good
luck.
Gene
------------------------- ppp.conf ---------------------------------------
default:
set device PPPoE:ed1
set MRU 1492
set MTU 1492
set speed sync
set authname username (substitute your user name)
set authkey password (substitute your PASSWORD)
set log command
set dial
set redial 0 0
set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.0 0.0.0.0
add 0 0 HISADDR
nat enable yes
set cd 5
enable lqr
enable proxy
set crtscts off
papchap:
set authname username (substitute your user name)
set authkey password (substitute your PASSWORD)
----------------------------------------------------------------------------------------
------------
God's Blessings,
Gene
To everything there is a season, and a time to every
purpose under heaven. Ecl 3:1 -
and more recently, The Byrds
rost...@yahoo.com
Thank you for your trying to help me. Your version of ppp.conf is very
similar to mine. I don't have LAN here, but only one box with FreeBSD
connected to the outside world through my ADSL modem. So ' set nat' and
' set proxy' options are not required in my case. I don't use
' set ifaddr' option because default arguments of it are good for me.
I think that the source of my problem isn't in ppp.conf probably,
but somewhere in TCP. Nobody answered me how MTU == MRU == 1484 solves
my problem. Maybe there is a bug in TCP when MTU and MRU have some
unstandard value. When I use Win98SE in the same box and the same ADSL
modem with RASPPPOE driver of PPPoE I have no troubles when the MTU is
1492 there. This is why I think the source of the problem is in TCP
implementation of FreeBSD. ppp have some dial with TCP, so maybe the
source of the problem is there but most likely not in ppp.conf
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rost...@yahoo.com
> look at the tcp mssfixup option in ppp
This option is enabled by default in ppp, look what `man 8 ppp` says:
[tcp]mssfixup
Default: Enabled. This option tells ppp to adjust TCP SYN pack-
ets so that the maximum receive segment size is not greater than
the amount allowed by the interface MTU.
Anyway, I enabled and disabled it manually in my ppp.conf but both
variants didn't help me. RASPPPOE in Win98SE in the same box have
similar option that is enabled by default too. I also didn't see any
difference when I disabled it there. The purpose of this option in both
FreeBSD's ppp and RASPPPOE is fixing MSS of connection between some
LAN's computer and external host when my box is the getway. But I have
no LAN here, my box connected only to my ADSL modem. This is why
'mssfixup' option have no influence in both operating systems that I
have in my computer. But when I use Win98SE with RASPPPOE I have no
problem with www.ssh.com, only when I use FreeBSD I have the trouble
with that host. Moreover, I still can't understand how
MRU == MTU == 1484 (or smaller) solves my problem?
In Win98SE with RASPPPOE I have MTU == 1492.
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da...@nersc.gov
--==_Exmh_1841889117P
Content-Type: text/plain; charset=us-ascii
Well, I noticed one thing from the tcpdump files -- in the 1492 case,
your machine is sending a FIN to www.ssh.com. In the 1484 case, of
course no FIN is sent. However, if you look at the 1492 tcpdump you'll
see connection establishment, a packet sent to www.ssh.com (an http
request I assume), a retransmit of that packet a second later
(implying that the first did not arrive), an ack for that packet from
www.ssh.com, and a fin from your box, which is then acknowledged.
I don't know what's causing it, but it appears that the application
you're using is seeing something it doesn't like, and is closing its
socket. I don't know why the www.ssh.com side does not send its own
FIN -- it should (it may also not be getting to you).
I would look at a tcpdump of a successful connection to
www.freebsd.org with the 1492 config (you said in an earlier post
that this works). You could also run with a slightly smaller MTU and
declare victory :)
--eli
In reply to Rostislav Krasny <rost...@yahoo.com> :
>
> --0-2081754345-1041105297=:86278
> Content-Type: text/plain; charset=us-ascii
> Content-Disposition: inline
>
> --- Eli Dart <da...@nersc.gov> wrote:
> >
> > In reply to Rostislav Krasny <rost...@yahoo.com> :
> >
> > > Thank you for your trying to help me. Your version of ppp.conf is very
> > > similar to mine. I don't have LAN here, but only one box with FreeBSD
> > > connected to the outside world through my ADSL modem. So ' set nat' and
> > > ' set proxy' options are not required in my case. I don't use
> > > ' set ifaddr' option because default arguments of it are good for me.
> > >
> > > I think that the source of my problem isn't in ppp.conf probably,
> > > but somewhere in TCP. Nobody answered me how MTU == MRU == 1484 solves
> > > my problem. Maybe there is a bug in TCP when MTU and MRU have some
> > > unstandard value. When I use Win98SE in the same box and the same ADSL
> > > modem with RASPPPOE driver of PPPoE I have no troubles when the MTU is
> > > 1492 there. This is why I think the source of the problem is in TCP
> > > implementation of FreeBSD. ppp have some dial with TCP, so maybe the
> > > source of the problem is there but most likely not in ppp.conf
> >
> > Are you blocking ICMP for "security reasons?" If so, you can't do
> > path mtu discovery, and tcp will break if it needs a smaller mtu
> > (which it appears that you do).
>
> No, I'm not blocking ICMP. I have recently installed FreeBSD 4.7-RELEASE
> with custom kernel that is a little simplified version of GENERIC. There
> is no firewall enabled, yet. Look at CUST01 file in the attachments, this
> is the configuration of the kernel of my system. I also ran `tcpdump -n`
> and saved its output when I ran `links www.ssh.com` in other terminal.
> I did it two times, the first when MRU == MTU == 1492 and the second when
> it was 1484. Look at 1492.log and 1484.log files in the attachments.
>
> P.S. If one blocks ICMP why he have troubles when MTU == MRU == 1492 but
> don't have the troubles when MTU == MRU == 1484 ?
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