Subject: Network issue........

From: Charlie <[email-masked]>
Date: Tue, 13 Sep 2016 16:26:55 +1000

Hello Debian Users,

I have a network issue that I find perplexing:

When I do: # netstat -r -n

or 

# route

Kernel IP routing table
Destination Gateway  Genmask Flags MSS Window irtt Iface
0.0.0.0       10.80.2.85  0.0.0.0     UG     0    0          0 eth0
10.80.2.84  0.0.0.0  255.255.255.252 U  0    0          0 eth0

But when I check it through my windows box it comes up as it should,
according to my ISP, with the gateway being 10.80.2.86

What is happening? Is it allowed to be that slack, one or the other?

TIA
Charlie
-- 
	Registered Linux User:- 329524
	***********************************************

	Appreciation is a wonderful thing: It makes what is excellent
	in others belong to us as well. -Voltaire

	***********************************************

	Debian GNU/Linux - Magic indeed.

	-----------------------------------------------------

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From: Joe Pfeiffer <[email-masked]>
Date: Tue, 13 Sep 2016 09:31:36 -0600

> What is happening? Is it allowed to be that slack, one or the other?

Do you know whether your gateway is doing any sort of network address
translation?  It seems odd to me that you're getting an address range
that matches the external address of your modem, and that your external
address is a 10.x.x.x (since those are all non-routable private IPs).
I'd expect either the former if no translation is being done, or the
latter if your external address weren't private.  But seeing both at the
same time surprises me.

On my home system, for instance, my comcast cable modem is at 10.1.10.1
internally, but 173.163.240.62 externally.

I have seen DHCP assign different addresses to Windows than to Linux,
but in your case the gateway box should be grabbing its address for
itself, and giving your computer the other available address.

---

From: Charlie <[email-masked]>
Date: Wed, 14 Sep 2016 09:00:51 +1000

On Tue, 13 Sep 2016 09:31:36 -0600 Joe Pfeiffer sent:

> that matches the external address of your modem, and that your
> external address is a 10.x.x.x (since those are all non-routable
> private IPs). I'd expect either the former if no translation is being
> done, or the latter if your external address weren't private.  But
> seeing both at the same time surprises me.
> 
> On my home system, for instance, my comcast cable modem is at
> 10.1.10.1 internally, but 173.163.240.62 externally.
> 

	After contemplation, my reply is:

What can I say?

I have no idea about networking and with the previous satellite system
and modem never had the problems I'm experiencing with this one.

Know nothing of network translation or external address.

Connecting directly to the modem with a standard Ethernet cat5 cable to
a vanilla, up to date Debian testing laptop, get the result posted.

Connecting to the same modem with the same cable to a windows 10
machine, I checked again this morning, because I could get a connection
through the modem after 54 minutes wait.

I get: IPv4 address 10.80.2.86

Which the person from my ISP was interested in.

I get: Default gateway 10.80.2.85

I don't know more than that?

I have been trying to discover what the problem is with my Satellite
internet connection. Doing this between outages by the NBN Co,
government arm, who own and run it.

It's decidedly tricky, and it's not like my Debian system is the
only one having these problems. They are also being experienced by
windows users on the same satellite system.

As an aside:

Connecting with an Ethernet cable to the wireless router I get:

Gateway 192.168.2.1
Destination 192.168.2.0

Thanks for taking the time and thinking about this problem I'm
experiencing. I will have to muddle through and just put up the long
wait to get an internet connection after turning on the modem.

Charlie

	To succeed in the world it is not enough to be stupid, you must
	also be well-mannered. -Voltaire

---

From: "Neal P. Murphy" <[email-masked]>
Date: Tue, 13 Sep 2016 19:18:50 -0400

On Wed, 14 Sep 2016 09:00:51 +1000

> wait to get an internet connection after turning on the modem.

Might it be related to the different MAC address? Might the ISP lock service to the MAC address it sees, at least for some period of time?

Get the MAC address of your Win10 system and set the NIC of your Debian system to it, for example:
    ip link set dev eth0 address aa:bb:cc:dd:ee:ff

See if it works any better once you've cloned the MAC address.

N

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From: Charlie <[email-masked]>
Date: Wed, 14 Sep 2016 09:40:20 +1000

On Tue, 13 Sep 2016 19:18:50 -0400 Neal P. Murphy sent:

> > > > 0.0.0.0       10.80.2.85  0.0.0.0     UG     0    0          0
> > > > eth0 10.80.2.84  0.0.0.0  255.255.255.252 U  0    0          0
> > > > eth0
> > > >
> > > > But when I check it through my windows box it comes up as it
> > > > should, according to my ISP, with the gateway being 10.80.2.86
> > > >
> > > Do you know whether your gateway is doing any sort of network
> > > address translation?  It seems odd to me that you're getting an
> > > address range that matches the external address of your modem,
> > > and that your external address is a 10.x.x.x (since those are all
> > > non-routable private IPs). I'd expect either the former if no
> > > translation is being done, or the latter if your external address
> > > weren't private.  But seeing both at the same time surprises me.
> > > 
> > > I have seen DHCP assign different addresses to Windows than to
> > > Linux, but in your case the gateway box should be grabbing its
> > > address for itself, and giving your computer the other available
> > > address.  
> > 
> > I have no idea about networking and with the previous satellite
> > system and modem never had the problems I'm experiencing with this
> > one.
> > 
> > Connecting directly to the modem with a standard Ethernet cat5
> > cable to a vanilla, up to date Debian testing laptop, get the
> > result posted.
> > 
> > machine, I checked again this morning, because I could get a
> > connection through the modem after 54 minutes wait.
> > 
> Might it be related to the different MAC address? Might the ISP lock
> service to the MAC address it sees, at least for some period of time?
> 
> Get the MAC address of your Win10 system and set the NIC of your
> Debian system to it, for example: ip link set dev eth0 address
> aa:bb:cc:dd:ee:ff
> 

The windows system doesn't find the internet connection either.

I try to connect with Debian by default and after some 30 or 40
minutes, a couple of reboots of the modem, bring my eth0 connection up
and down a couple of times. do direct connection to the modem. If no
connection found.

Couple up the windows 10 lappy. First through the wireless non
connection, rebooting the lappy a couple of times, then the Ethernet
cable through wireless router and then finally direct to the modem.

Then, because the connection hasn't been found. I return to the Debian
lappy, knowing now it's not that system and as I work keep trying
things and after maybe an hour or often more, get onto a connection.

One day didn't get on for 2 days, but that was a NBN outage for that
period.

Thanks for the suggestion.
Charlie

	However mean your life is, meet it and live it; do not shun it
	and call it hard names. It is not so bad as you are. It looks
	poorest when you are the richest. -Henry David Thoreau

---

From: "Neal P. Murphy" <[email-masked]>
Date: Tue, 13 Sep 2016 19:50:07 -0400

On Wed, 14 Sep 2016 09:40:20 +1000

> Thanks for the suggestion.

Try:
  - turn off the modem for 5 minutes (or longer, if needed; it may take longer
    for the ISP to 'reset')
  - turn the modem on
  - see if Debian will connect

Does the ISP use DHCP? Or does it use PPPoE? If DHCP, you might try:
  tcpdump -v -i eth0 port 67 or port 68
to see the DHCP traffic. (There may be other options you can add to display more info or better DHCP protocol decoding.)

---

From: Fabrizio Carrai <[email-masked]>
Date: Tue, 13 Sep 2016 13:00:15 +0200

I suppose you are using DHCP: the gw is assigned by the service.

---

From: Darac Marjal <[email-masked]>
Date: Tue, 13 Sep 2016 09:54:08 +0100

>10.80.2.84  0.0.0.0  255.255.255.252 U  0    0          0 eth0

This translates as "For 10.80.2.84 to 10.80.2.87, talk directly to the 
host, otherwise gateway through 10.80.2.85".

You don't mention how this route has been allocated, though. Are you 
using DHCP and these routes are being offered to you by a router? Have 
you entered them manually in /etc/network/interfaces?

>according to my ISP, with the gateway being 10.80.2.86

Again, you don't detail how Windows has got this information.

At the moment, the problem could simply be that you mis-typed one or 
other of the IP addresses when entering them.

-- 
For more information, please reread.

---

From: Charlie <[email-masked]>
Date: Tue, 13 Sep 2016 21:30:11 +1000

On Tue, 13 Sep 2016 09:54:08 +0100 Darac Marjal sent:

> This translates as "For 10.80.2.84 to 10.80.2.87, talk directly to
> the host, otherwise gateway through 10.80.2.85".
> 
> using DHCP and these routes are being offered to you by a router?
> Have you entered them manually in /etc/network/interfaces?

The gateway is a satellite modem that has been supplied by the national
satellite service.

The Debian Linux testing box declares it, as mentioned above, on the
command line with either of the two commands mentioned above also. 

The windows 10 box, says the IP address of the gateway is different to
the Debian system, which unfortunately I have been quoting, [as above]?
[cringing] Thinking it was right, and obviously not.

The windows 10 box, on the admin command line type: ipconfig/all 
Shows me the DNS, the ipv4 gateway as mentioned etc., etc..

The Linux system uses DHCP, is that a bad thing?

Windows 10 has DHCP enabled as well. Is that a bad thing? Has
autoconfiguration enabled also.

Anyway windows 10 has it right apparently, Debian does not.

So If I want to make a complaint in the future, will have to trouble
shoot it with the windows 10 system.

Obviously no explanation for the different numbers.

Ce la vie. Thanks for the input.

	Getting bored is not allowed. -Eloise

---

From: [email-masked]
Date: Tue, 13 Sep 2016 07:07:51 -0400

> host, otherwise gateway through 10.80.2.85".

I'm not the OP, but maybe I can learn something.  

I can sort of see where you got the 10.80.2.84--oh, and I was going to say 
that I don't see where the 10.80.2.87 came from, but, without doing the math, 
maybe that comes from the 255.255.255.252 netmask?

---

From: Darac Marjal <[email-masked]>
Date: Tue, 13 Sep 2016 12:20:30 +0100

>maybe that comes from the 255.255.255.252 netmask?

Yes. I actually plugged the numbers into 
http://www.subnet-calculator.com/ as I'm lazy, but 255.255.255.252 is 
also written as /2 and it defines a subnet where everything but the last 
2 bits of the address are the same. We're lucky that, in this instance 
10.80.2.84 is on the lower boundary of this range (Actually, the routing 
table might enforce that), so the next 4 (inclusive) hosts make up the 
range .84 (which would usually be the 'network' address), .85 and .86 
(which are both 'usable' hosts) and .87 (which would be the 'broadcast' 
address).

---

From: Erwan David <[email-masked]>
Date: Tue, 13 Sep 2016 13:28:36 +0200

On Tue, Sep 13, 2016 at 01:20:30PM CEST, Darac Marjal <[email-masked]> said:
> Yes. I actually plugged the numbers into http://www.subnet-calculator.com/
> as I'm lazy, but 255.255.255.252 is also written as /2 and it defines a
> subnet where everything but the last 2 bits of the address are the same.
> We're lucky that, in this instance 10.80.2.84 is on the lower boundary of
> this range (Actually, the routing table might enforce that), so the next 4
> (inclusive) hosts make up the range .84 (which would usually be the
> 'network' address), .85 and .86 (which are both 'usable' hosts) and .87
> (which would be the 'broadcast' address).

That's /30 (30 fixed bits) not /2