Network problems

[Bill Stanley]

On 12/23/2010 12:21 PM, Tom H wrote:
> On Thu, Dec 23, 2010 at 3:45 AM, Lucio M Nicolosi<lmnicolosi at gmail.com>  wrote:
>> On Wed, Dec 22, 2010 at 5:14 PM, Bill Stanley<bstanle at wowway.com>  wrote:
>>>
>>> I'm not certain if I am running two firewalls.  I assume I am because I
>>> know I installed the gufw firewall on the computer that doesn't respond
>>> to a ping.   I assume that Unbuntu installs a firewall by default.  If
>>> so what is its name because I don't see any evidence of it.  This is the
>>> first firewall I assume I have.  If there isn't one, then I have gufw only.
>>>
>>>   The strange thing is that I use the unaffected computer to do a port
>>> scan (using the system/administration/network tools) and can get some
>>> output back from the affected computer.
>>>
>>> The output of the port scan (from the unaffected computer) is...
>>>
>>> PORT  STATE  SERVICE
>>> 111   open   sunprc
>>> 2049  open   nfs
>>> 40837 open   unknown
>>> 45314 open   unknown
>>> 50038 open   unknown
>>>
>>> When I do a port scan from the affected computer (of its port status i
>>> get...
>>>
>>> Port   State   service
>>> 111    open    sunprc
>>> 2049   open    nfs
>>> 40837  open    unknown
>>> 45314  open    unknown
>>> 50038  open    unknown
>>> 52826  open    unknown
>>>
>>> I am somewhat concerned about the open ports with an unknown service.
>>> Is there any way to get more information about those services?
>>>
>>> I notice that the unaffected computer can see the nfs service running on
>>> the affected computer.  If I can see the nfs service running, what must
>>> be done to share files using the nfs service.
>>
>> Although Ubuntu comes loaded with iptables, the core of any firewall,
>> if no rules are set it "doesn't work". Gufw is just a graphic
>> interface to iptables that enables easy handling of rules. I don't
>> have Gufw installed right now and I can't remember if it can disable
>> ping requests, (anyway, yours is probably unconfigured) like some DSL
>> routers can do.
>
> For the sake of future googlers: it isn't that the firewall doesn't
> work on a default Ubuntu install, it's that there are no rules loaded;
> gufw is a graphical front-end of ufw, which is itself a front-end
> (with rule syntax similar to one of the BSDs) to iptables.
>
> So having both ufw and gufw doesn't mean that you have two firewalls
> installed and if you don't enable ufw (through the CLI or GUI) or
> write or load some rules with iptables you won't have a firewall
> running.
>
> I don't see any samba ports in your output above. Are you sure that
> you have samba running? How did you set up the shares?
>
> For nfs, you must have it installed. To export a directory, you have
> to edit "/etc/exports".
>

I think you misunderstand my problem.  If I understand samba correctly, 
it is for connection a windows machine to a Linux machine.  I can't get 
two Linux machines (both running Unbuntu) to communicate.  If I am 
right, samba is not needed but nfs is needed.  After I get the two to 
communicate I will attempt to add my third computer which is a Windows 
machine.  Of course to do that samba will be needed but for the moment 
it should not be needed.

The problem might not be a firewall problem.  Then again, I really don't 
know which is why I am asking for help.