Re: CentOS Networking with V Box

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Author: Michael Torres
Date:  
To: Main PLUG discussion list
Subject: Re: CentOS Networking with V Box
OK, when I start/stop the network service, I use the following command....

[root@devserver]# /etc/init.d/network stop
    Stopping network (via systemctrl)



[root@devserver]# /etc/init.d/network start
    Starting network (via systemctrl)


Then I run the commands that you gave earlier after starting fails...


This is the result..

network.service loaded failed failed LSB: Bring up/down networking




On Tue, Feb 3, 2015 at 11:47 PM, Kevin Fries <> wrote:

> If your interface has no IP, you can't communicate out to anywhere, and we
> are back to the conversation about starting and enabling your network
> service.
> On Feb 3, 2015 11:45 PM, "Michael Torres" <> wrote:
>
>> thats the point.... I dont have an IP address...there is nothing that I
>> put to scan it. My NIC was allowing it when I was at Starbucks.. That is
>> why I think its my router, as such isnt the router that assigns IP address
>> to the network when using DHCP?
>>
>> On Tue, Feb 3, 2015 at 11:39 PM, Kevin Fries <>
>> wrote:
>>
>>> Ok, down to two possibilities.
>>>
>>> Nmap is a scanner. It is trying to identify your VM and probe for open
>>> ports.
>>>
>>> When you scanned by name... it did not understand that name. Your
>>> router is external to all of this, and should not be involved at all.
>>>
>>> Try nmap by IP address.
>>>
>>> If that still results in nothing, add a virtual network via VMware or
>>> VBox. Next add a new virtual network adapter to your VM, and connect it to
>>> the new network. This should be a private network between host and
>>> client. Config your interface in the VM. This will resolve your problem.
>>> In this case, your NIC is not allowing traffic to go out, then back in to
>>> itself. The traffic is almost certainly not going to your router then back.
>>>
>>> HTH
>>> Kevin
>>> On Feb 3, 2015 10:41 PM, "Michael Torres" <> wrote:
>>>
>>>> netstat -plant
>>>>
>>>> liastening on ports 25 and 22 both for IPv4 nad IPv6
>>>>
>>>> Result from the nmap(windows version)
>>>> Starting Nmap 6.47 ( http://nmap.org ) at 2015-02-03 22:36 US Mountain
>>>> Standard Time
>>>>
>>>> NSE: Loaded 118 scripts for scanning.
>>>>
>>>> NSE: Script Pre-scanning.
>>>>
>>>> NSE: Script Post-scanning.
>>>>
>>>> Read data files from: C:\Program Files (x86)\Nmap
>>>>
>>>> Nmap done: 0 IP addresses (0 hosts up) scanned in 4.20 seconds
>>>>
>>>>            Raw packets sent: 0 (0B) | Rcvd: 0 (0B)

>>>>
>>>> Failed to resolve "devserver".
>>>>
>>>> WARNING: No targets were specified, so 0 hosts scanned.
>>>>
>>>> I would ahave asusmed the the above results as the dhcp server is not
>>>> generating a IPv4 address
>>>>
>>>>
>>>> so...
>>>>
>>>> 1) The netstat does not show the binding to port 21... this means
>>>> SSHD did not start.
>>>>
>>>> I am guessing port 22 is OK
>>>>
>>>> 2) netstat shows SSHD, but the firewall is not allowing it. Open the
>>>> firewall
>>>>
>>>> Firewall is already disabled
>>>>
>>>> 3) netstat shows SSHD, the firewall is open, but you still don't see
>>>> the port open via nmap.
>>>>
>>>>     3a) if you see other ports open, I would look at the Windows
>>>> firewall

>>>>
>>>> Windows firewall allowed it on a Public network (startbuck), so why not
>>>> allow it at my home
>>>>
>>>>     3b) If you don't see any ports open, you have two options here.

>>>>
>>>>        3b1) Make sure your NIC (from the Windows side) is in
>>>> promiscuous mode.

>>>>
>>>> dont know how to do that.
>>>>
>>>>        3b2) If it is already in promiscuous mode, then this may not
>>>> work in this configuration.  In this case, try adding a private network on
>>>> a second NIC, and communicate with the VM over that.
>>>> Ill try to connect to my ethernet adpater and see if that is it, maybe
>>>> its my wireless adapter....

>>>>
>>>> Mike
>>>>
>>>>
>>>> On Tue, Feb 3, 2015 at 10:22 PM, Kevin Fries <>
>>>> wrote:
>>>>
>>>>> Ok, sorry, I misunderstood.
>>>>>
>>>>> Nmap could be your friend here. Install it on your Windows machine.
>>>>> It will install the graphical tool automatically in Windows. Point this at
>>>>> your VM, and do a "intense scan"
>>>>>
>>>>> Next, on the Linux VM, do a
>>>>> # netstat -plant
>>>>>
>>>>> Zenmap/Nmap will tell you what ports it can see open from its side of
>>>>> the link. The netstat command will tell you which ports are opened by
>>>>> running software.
>>>>>
>>>>> Lastly, on the Linux VM, do a
>>>>>    # ip tables -L

>>>>>
>>>>> This will tell you which ports the firewall will allow.
>>>>>
>>>>> Now, you have a few possibilities:
>>>>>
>>>>> 1) The netstat does not show the binding to port 21... this means
>>>>> SSHD did not start.
>>>>>
>>>>> 2) netstat shows SSHD, but the firewall is not allowing it. Open
>>>>> the firewall
>>>>>
>>>>> 3) netstat shows SSHD, the firewall is open, but you still don't see
>>>>> the port open via nmap.
>>>>>
>>>>>     3a) if you see other ports open, I would look at the Windows
>>>>> firewall

>>>>>
>>>>>     3b) If you don't see any ports open, you have two options here.

>>>>>
>>>>>        3b1) Make sure your NIC (from the Windows side) is in
>>>>> promiscuous mode.

>>>>>
>>>>>        3b2) If it is already in promiscuous mode, then this may not
>>>>> work in this configuration.  In this case, try adding a private network on
>>>>> a second NIC, and communicate with the VM over that.

>>>>>
>>>>> Let me how it goes.
>>>>>
>>>>> Kevin
>>>>> On Feb 3, 2015 9:58 PM, "Michael Torres" <>
>>>>> wrote:
>>>>>
>>>>>> Well, no, I didnt issue any commands other than
>>>>>> /path/to/network/script/network start /path/to/network/script/network stop
>>>>>> and the commands to disable firewall/SELINUX
>>>>>>
>>>>>> I know I didnt use any systemctrl commands., but I tried to run the
>>>>>> commands that you just provided and nothing happened. I should probably
>>>>>> say that I know that IPv6 is enalbed and have network connection to the net
>>>>>> work and I can ping yahoo.com etc..... I just cant SSH(putty) to
>>>>>> the server.
>>>>>>
>>>>>> This all leads me to beleive that there is a configuration in my
>>>>>> router that is not allowing me to get a IPv4 address. Does the default
>>>>>> gateway have to be a certain number? I have manually configured that IP on
>>>>>> my router a long time ago, but even then I had Bridged networking working
>>>>>> correctly.
>>>>>>
>>>>>> Mike
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tue, Feb 3, 2015 at 9:48 PM, Kevin Fries <>
>>>>>> wrote:
>>>>>>
>>>>>>> Your network is probably not getting started. The enp0p3 is the
>>>>>>> name of an interface started almost definantly by systemd, not the old
>>>>>>> RHEL way. This is likely why the networking-scripts didn't work.
>>>>>>>
>>>>>>> When you were at Starbucks, you likely did a systemctl start on the
>>>>>>> interface. Look in your history for it. If you find it, issue the same
>>>>>>> command again. If your interface comes up correctly, reissue the command
>>>>>>> once again, substituting enable for start. This second command is similar
>>>>>>> to a chkconfig command.
>>>>>>>
>>>>>>> Let me know how that works.
>>>>>>>
>>>>>>> Kevin
>>>>>>> On Feb 3, 2015 9:13 PM, "Michael Torres" <>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> The result of that command is:
>>>>>>>>
>>>>>>>> 0 loaded units listed
>>>>>>>>
>>>>>>>>
>>>>>>>> So I ran a what it suggested: systemctl list-unit-files
>>>>>>>> majority of everything says "static" but some are "enabled" or
>>>>>>>> "disabled"
>>>>>>>>
>>>>>>>> again, because I cannot copy or capture a screen shot, is there a
>>>>>>>> specific list item that you need to see?"
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, Feb 3, 2015 at 8:44 PM, Kevin Fries <>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Do a
>>>>>>>>>
>>>>>>>>> # systemctl --failed
>>>>>>>>>
>>>>>>>>> And post the results
>>>>>>>>>
>>>>>>>>> Kevin
>>>>>>>>> On Feb 3, 2015 8:37 PM, "Michael Torres" <>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>> Arrghh....yes its configured. But I am having an issue getting
>>>>>>>>>> the cat /etc/sysconfig/network-script/ifcfg-enp0s3..........because I cant
>>>>>>>>>> connect, I cant ssh in to use outty so I can copy using my mouse. I tried
>>>>>>>>>> taking a screen shot, but VBox for some reason wont display on on the
>>>>>>>>>> "print screen"command.
>>>>>>>>>>
>>>>>>>>>> is there a particular setting you are looking for? again, the
>>>>>>>>>> file is configured and it is reading it.
>>>>>>>>>>
>>>>>>>>>> Mike
>>>>>>>>>>
>>>>>>>>>> On Tue, Feb 3, 2015 at 8:15 PM, Stephen M <>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>> I don't remember if this is a problem in centos 7 as it was in
>>>>>>>>>>> 6. But check to make sure the eth0 is configured. But yes a print out of
>>>>>>>>>>> ifconfig inside vox would be great.
>>>>>>>>>>> On Feb 3, 2015 8:07 PM, "Michael Torres" <>
>>>>>>>>>>> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> Hello all,
>>>>>>>>>>>>
>>>>>>>>>>>> I have an problem that I cannot seem to figure out.....
>>>>>>>>>>>>
>>>>>>>>>>>> I am trying to use "Bridged" networking in Virtual Box to a
>>>>>>>>>>>> CentOS 7 minimum install distro that I want to use for my development
>>>>>>>>>>>> server.
>>>>>>>>>>>>
>>>>>>>>>>>> I have used Bridged networking in the past and never had any
>>>>>>>>>>>> issues but that was with older versions of CentOS
>>>>>>>>>>>>
>>>>>>>>>>>> The issue.... DHCP will not assign a IPv4 address to the
>>>>>>>>>>>> server.
>>>>>>>>>>>>
>>>>>>>>>>>> Here is the weird part... I was at startbucks and actually got
>>>>>>>>>>>> it to work! (Please, hold the "Just use it at starbucks then" comments..I
>>>>>>>>>>>> know....)
>>>>>>>>>>>>
>>>>>>>>>>>> Here is the process I used...
>>>>>>>>>>>>
>>>>>>>>>>>> -Installed a fresh CentOS 7 on VBox
>>>>>>>>>>>> -While on NAT, I performed "yum update" so my server was fresh
>>>>>>>>>>>> with the latest
>>>>>>>>>>>> -Disabled SELinux
>>>>>>>>>>>> -Disabled the Firewall
>>>>>>>>>>>> -Shut down server to reconfigure the adapter to "Bridged"
>>>>>>>>>>>> -used adapter type of "Intel Pro 1000 MT Desktop (82540EM)"
>>>>>>>>>>>> -set it to "Promiscuous Mode"
>>>>>>>>>>>> -restart the server
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Again, at Starbucks it assigned a IP address, so this leads me
>>>>>>>>>>>> to believe that the issue is with a configuration on my router.
>>>>>>>>>>>>
>>>>>>>>>>>> I am not very good at networking, so any help would be
>>>>>>>>>>>> appreciated.
>>>>>>>>>>>>
>>>>>>>>>>>> If you need error messages or other output, let me know (and
>>>>>>>>>>>> possibly the command as I don't know networking that well other than
>>>>>>>>>>>> "ifconfig")
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Mike
>>>>>>>>>>>>
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