Basic networking fail.

[diw]

Hiya.

I usually use dhcp to connect OpenBSD to the internet and haven't had to concern myself with much more than hostname.if at least for a long time anyway.

ATM, I have a "router box" that I wish to use as a gateway to the internet for my desktop.
This is the topology:

Internet<==========>vr2@router@vr1<============>fx p0@desktop

Very simple.
As a minimum, I am able to plug my Internet (from my modem) into any of these adapters and get the web. A simple "dhcp" on a line in the relevant hostname.if file sees to that. :]

The next simple step in connectivity is to get the route from vr1 to fxp0 working, at least at the IP address level.
Here are my hostname.if files:
hostname.vr1 >
inet 192.168.255.250 255.255.255.0
hostname.fxp0 >
inet 192.168.255.0 255.255.255.0

My experience on that other O.S. tells me this is enough to do a ping test.
Unfortunately in this case it doesn't work.
I have tried with a known good cable. I can see the adapter lights at both ends flashing @ about the speed of the default ping packets.

Please let me know what to do.
As to be expected with OpenBSD it will be my fault.
Still I need to take precautions.
I have mercenaries waiting on the tarmac. The flight plan is for Alberta.
These guys are costing me a fortune and are starting to get antsy.

Best wishes.

[BSDfan666]

Well, it sounds you're using a strait through cable.. that won't work unless at least one of the interfaces supports AutoMDIX sensing.

If it's a crossover cable, please post ifconfig+route show output here in [code][/code] blocks.

[ocicat]

Originally Posted by diw

hostname.fxp0 >
inet 192.168.255.0 255.255.255.0

Given the subnet mask 255.255.255.0 specified, the following two addresses cannot be used for specific interfaces:

• 192.168.255.0/24 -- subnet address
• 192.168.255.255/24 -- subnet's broadcast address

Any other address between 192.168.255.1 -- 192.168.255.254 can be used for individual interfaces.

[BSDfan666]

Great catch ocicat, I'm not sure how I missed it..

[diw]

Originally Posted by BSDfan666

Well, it sounds you're using a strait through cable.. that won't work unless at least one of the interfaces supports AutoMDIX sensing.

That was what I first thought of.
When I did my feedback to the "router" distributor I suggested they add crossover cables to their catalogue.
He emailed me:

The ethernet ports on the ALIX 2-3 are autosensing for crossover/straight connections, so any cable should do the trick if yo don't find a crossover cable anywhere.

It turns out that ocicat got it as you noted. :]

Best wishes.

[diw]

Originally Posted by ocicat

Given the subnet mask 255.255.255.0 specified, the following two addresses cannot be used for specific interfaces:

• 192.168.255.0/24 -- subnet address
• 192.168.255.255/24 -- subnet's broadcast address

Any other address between 192.168.255.1 -- 192.168.255.254 can be used for individual interfaces.

I guess this is one of the differences between that other O.S. and OpenBSD.
I could use x.x.x.255 (and I suspect x.x.x.0 also) for an adapter if I wanted to.
Can you tell me what the purpose of reserving the x.x.x.0 address is? Is it because it is effectively masked by the netmask?

Oh, and of course now I can ping.

Best wishes.

[diw]

Originally Posted by BSDfan666

Great catch ocicat, I'm not sure how I missed it..

Perhaps I could get a job writing exam question for BSD Certification.
Ask a few noob questions from my real life experience.
Guaranteed to trip up one out of every two experienced admins.

Best wishes.

[robbak]

I was thinking of reminding you that the modem/router often needs a routing entry as well. It's something I often forget to do.

[ocicat]

Originally Posted by diw

I guess this is one of the differences between that other O.S. and OpenBSD.

The information I was conveying is standard IP addressing knowledge supported by various RFC's. I don't know what other operating system you are referring to, but 192.168.255.0/24 should not be an acceptable IP address in any environment.

Can you tell me what the purpose of reserving the x.x.x.0 address is?

It is not a question of x.x.x.0 by itself; it is a question of x.x.x.0 coupled with a 255.255.255.0 subnet mask. There are subnets where x.x.x.0 may be completely legal to address a specific interface. The fundamental issue is where all host bits within an overall IP address are set to zero as this defines the subnet itself. It is common for routing tables to retain subnet addresses in this form in order to route packets. For more information, study RFC 1812:

http://www.faqs.org/rfcs/rfc1812.html

[ocicat]

You may benefit from studying IP addressing fundamentals. One of the better sources I have found is the following:

http://www.3com.com/other/pdfs/infra..._US/501302.pdf

...however, note that there are some formatting errors where superscripts (exponents) are not rendered correctly. If you do the math on pencil & paper while reading, these errors will be readily apparent.

This paper may seem a bit dated, but the fundamentals it covers are still correct. It is good at providing context to the problems IP addressing is attempting to solve.

[diw]

Originally Posted by ocicat

... 192.168.255.0/24 should not be an acceptable IP address in any environment.

"should not be" being the relevant phrase.

Best wishes.

[diw]

Originally Posted by ocicat

One of the better sources I have found is the following:
http://www.3com.com/other/pdfs/infra..._US/501302.pdf

It looks similar to the quite popular 3COM guide from years ago.
I don't think I could stand the nostalgia. :]

Originally Posted by ocicat

For more information, study RFC 1812:
http://www.faqs.org/rfcs/rfc1812.html

I have referred to rfc1812 many times thanks.
Usually I go to the source. :]
http://www.ietf.org/

Originally Posted by diw

Can you tell me what the purpose of reserving the x.x.x.0 address is? Is it because it is effectively masked by the netmask?

FWIW, you could have said "yes, that's correct".
Then I could have said "of course - how stupid of me".
Stuff I used to be interested in.

Best wishes.

[jggimi]

The high-level address is the broadcast address ... and while broadcast IP is pretty much a dead-thing-from-before-the-Internet, broadcast may be enabled and used, so the broadcast address is still reserved.

[diw]

Originally Posted by jggimi

The high-level address is the broadcast address ... and while broadcast IP is pretty much a dead-thing-from-before-the-Internet, broadcast may be enabled and used, so the broadcast address is still reserved.

Thanks sport.
I did notice that OpenBSD does use the default broadcast address - ifconfig shows that.
I expect that Theo will peruse RFCs night and day to find obscure ways to torture me.
And so he should.

Best wishes.

BTW, I am almost ready for my idjoot questions on myname ...
Oh, and why I don't have a route through my gateway ...