LAN question

[Joel Rees]

On Sep 15, 2008, at 1:56 PM, Paul Newell wrote:

> Fedora:
>
> Before I switched to F9, all my FC5 machines were happily chatting  
> with each other through a Linksys WRT54GL but none of them could  
> see the net.

How did you set this up originally? Apparently not DHCP, from what  
you've written about /etc/hosts, but what machine(s) did you specify  
as the name server(s)?

> I upgraded one of them to F9 and it sees the net and can ssh to the  
> others.

So, when you upgraded the one, you probably gave the install script a  
DNS server address or two?

> But the other two machines can no longer ssh into it F9 system.

And I must admit, based on the /etc/hosts below, that I'm wondering  
how you did before. ssh to a numerical IP address, perhaps?

> I tried to play with things to fix it, but the best I could do was  
> kill the network connection so that the F9 system can't see the  
> other machine or the net. In other words, I screwed up. Since I  
> can't figure out how to get the network back alive by restoring  
> prior conditions, I am resigned to yet another re-install (the  
> price of learning is lots of starting over...)

If it's a slow machine, I hope you haven't already started. Waste a  
good learning opportunity.

Did you backup /etc/hosts before the upgrade, by the way?

> That being said, I was hoping to get a bit of advice.
>
> The following is the F9 /etc/hosts file after 1) a fresh install of  
> f9 and 2) my additions (noted with comments):
>
>    # Do not remove the following line, or various programs
>    # that require network functionality will fail.
>    127.0.0.1        chowder.localdomain chowder localhost.localdomain
>    localhost chowder

Any reason to have chowder in there twice?

>    ::1        localhost6.localdomain6 localhost6
>
>    #-# 14sep08 (paul): self
>    192.168.2.11    chowder

I usually don't put this line in, just leave the declaration with  
localhost to take care of it.

>    #-# 14sep08 (paul): other machines available
>    192.168.2.10    chalupa
>    192.168.2.12    parsnip
>
> The next section is from one of the FC5 machines:
>
>    # Do not remove the following line, or various programs
>    # that require network functionality will fail.
>    127.0.0.1    localhost.localdomain    localhost
>
>    #-# self
>    192.168.2.12    parsnip

I would have put that up there on 127.0.0.1 like you did with chowder.

>    #-# other machines available
>    192.168.2.10    chalupa      192.168.2.11    chowder

Should we assume that somehow two lines got combined when you pasted  
that here, or is this the reason parsnip can't see chowder?

If that's one line in your hosts file, I'm pretty sure it would  
prevent parsnip from seeing chowder. In fact, it would likely make  
strange things happen, like mapping "192.168.2.11" (as a string) and  
"chowder" to to 192.168.2.10 along with chalupa. Just for parsnip, of  
course.

> I am suspect of the "localdomain" in the F9 version, but trying to  
> play with that is what killed network (LAN and internet) ability.

Hmm. What was the 127.0.0.1 line when chowder was seeing the  
internet? And did you specify any dns servers when you set up chowder?

> I went through the system->admin->network stuff and couldn't see  
> anything that looked wrong (then again, do I know what is right?)
>
> As always, suggestions appreciated (including general pointers as  
> to where to go online to learn more about all this)
>
> Thanks,
> Paul

[...]

> I did want to add the following in case it makes any difference in  
> your advice. My plan is to convert all the FC5 machines to F9 once  
> I am confident in the F9 machine and my understanding of it. None  
> of the machines are servers, they are three independent  
> workstations that just need to ssh/scp/"s-etc" to each other. I  
> would hope that each could independently access the internet and  
> each other.

Have you got a file in /etc/sysconfig/network-scripts called ifcfg- 
eth0 or something similar? (ifcfg-something-other-than-lo)

Does it look something like this:
-----------------------------------
DEVICE=eth0
BOOTPROTO=none
BROADCAST=192.168.2.255
# HWADDR is your NIC's MAC address, six bytes in hexadecimal
HWADDR=00:0e:3a:b2:51:fc
IPADDR=192.168.2.11
NETMASK=255.255.255.0
NETWORK=192.168.2.0
ONBOOT=yes
DNS1=<your-isp-dns-server-1>
DNS2=<your-isp-dns-server-2>
# I don't remember what SEARCH is set to by default, maybe  
"localdomain"?
# (In my case it is the domain name I get from dyndns.com.)
SEARCH="localdomain"
# This next line was giving me trouble earlier because I had left it no,
# but was using network manager:
NM_CONTROLLED=yes
# GATEWAY would be the IP address of your Linksys.
GATEWAY=192.168.2.1
TYPE=Ethernet
# I'm not sure what USERCTL and PEERDNS do at this point.
USERCTL=no
PEERDNS=yes
IPV6INIT=no
------------------------------------

That file is used by the startup scripts when they call ifconfig to  
bring your NICs up, as I understand it.

Here's a page that will tell you more:

http://www.redhat.com/docs/manuals/enterprise/RHEL-3-Manual/ref-guide/ 
s1-networkscripts-interfaces.html

(And I think I'll go review it, myself.)

Joel Rees