Please Help Me Understand Host-Only Networking

F

FredericP

Bit poster
This has me quite frustrated. I need to carry my laptop and give product (software) demonstrations. Here is my setup:

Host: Macbook Pro (2.66 GHz, 4 GB RAM, 500 GB HDD, OS X 10.6.4), Parallels Desktop build 5.0.9370.
Guest OS: CentOS 5.5 Linux, 64-bit. Oracle 11gR2 database
(Optional Guest OS: Windows 7)

I have made the above configuration work in my local network (192.168.1.x). I can reach the Oracle database from any machine on my network -- real or virtual.

However, I cannot get connectivity when I am disconnected from a network. Or even if I go to host-only networking.

I have set my Parallels preference to host-only, DHCP enabled, using the 192.168.1.x structure. When the CentOS starts up, it grabs an IP address from the Parallels DHCP, but that's where connectivity stops. I cannot even ping in or ping out (to/from the guest OS). Obviously, I cannot access my Oracle without some connectivity.

I've read the manual, but it doesn't seem to address this. Am I missing something obvious? It must be, for the whole idea of host-only networking is to allow the VM to communicate with the host, correct?
 
please switch the VM to HostOnly and post here the output of
1) "ifconfig -a" from the VM
2) "ifconfig -a" from Mac OS (start the /Application/Utilities/Terminal)
3) output of ping from VM to Mac
4) output of ping from Mac to VM
 
Output Results

Thank you for your reply. Here are the outputs.

From the Linux guest, in host-only mode:

[root@centos64 ~]# ifconfig -a
eth0 Link encap:Ethernet HWaddr 00:1C:42:D6:08:86
inet addr:192.168.1.240 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::21c:42ff:fed6:886/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:241 errors:0 dropped:0 overruns:0 frame:0
TX packets:313 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:40205 (39.2 KiB) TX bytes:54664 (53.3 KiB)
Interrupt:10 Base address:0x8200

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:107225 errors:0 dropped:0 overruns:0 frame:0
TX packets:107225 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:19866969 (18.9 MiB) TX bytes:19866969 (18.9 MiB)

sit0 Link encap:IPv6-in-IPv4
NOARP MTU:1480 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

[root@centos64 ~]#

From the Mac host (Airport active):

ifconfig -a
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
inet6 ::1 prefixlen 128
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1
inet 127.0.0.1 netmask 0xff000000
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 58:b0:35:fc:53:00
media: autoselect
status: inactive
en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether f8:1e:df:ee:7a:fa
inet6 fe80::fa1e:dfff:feee:7afa%en1 prefixlen 64 scopeid 0x5
inet 192.168.1.8 netmask 0xffffff00 broadcast 192.168.1.255
media: <unknown subtype>
status: active
fw0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 4078
lladdr e8:06:88:ff:fe:aa:0a:08
media: autoselect <full-duplex>
status: inactive
vboxnet0: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 0a:00:27:00:00:00
vnic0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 00:1c:42:00:00:08
inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
media: autoselect
status: active
vnic1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
ether 00:1c:42:00:00:09
inet 192.168.1.239 netmask 0xffffff00 broadcast 192.168.1.255
media: autoselect
status: active

Ping: VM to Mac (four ping limit):

[root@centos64 ~]# ping -c 4 192.168.1.8
PING 192.168.1.8 (192.168.1.8) 56(84) bytes of data.
From 192.168.1.240 icmp_seq=1 Destination Host Unreachable
From 192.168.1.240 icmp_seq=2 Destination Host Unreachable
From 192.168.1.240 icmp_seq=3 Destination Host Unreachable
From 192.168.1.240 icmp_seq=4 Destination Host Unreachable

--- 192.168.1.8 ping statistics ---
4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 3005ms
, pipe 3
[root@centos64 ~]#

Ping: Mac to VM (four ping limit):

ping -c 4 192.168.1.240
PING 192.168.1.240 (192.168.1.240): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2

--- 192.168.1.240 ping statistics ---
4 packets transmitted, 0 packets received, 100.0% packet loss

I appreciate any assistance.
 
Here are the errors!

en1: inet 192.168.1.8 netmask 0xffffff00 broadcast 192.168.1.255
vnic0: inet 192.168.1.2 netmask 0xffffff00 broadcast 192.168.1.255
vnic1: inet 192.168.1.239 netmask 0xffffff00 broadcast 192.168.1.255

The networking (in general, not only the parallels) uses the pair address/mask to detect to which network card (en1/vnic0/vnic1) forward the data and since all three cards have the same value of address&mask (== 192.168.1.x), Mac OS doesn't know to which net-card direct the packet.

So, this configuratioin will not work.. You need to go to the preferences and press "Restore Defaults"-button for networking.

==

May be you can consider the following configuration:

add second network card to Parallels VM. Let's first card will be in Bridged mode and second one in HostOnly mode.

In this case you will always be able to connect to VM by it's host only IP-address (will be displayed by running command ipconfig -a inside VM).
 
Thank you for your ongoing responses. I'm afraid I'm still not following you, though. I cannot add another adapter, as neither Parallels nor the CentOS VM will allow it. I can bind a new "pseudo" adapter in the VM to the same card, and ifconfig will show both IP addresses, but I'm still left with the inability to direct traffic in or out of the VM.
 
You can add adapters to a VM when the VM is not running (see screen shot below).

The Restore Defaults button is at Parallels Desktop -> Preferences... -> Network.

I think Host-only networking refers to vnic1 and Shared Networking refers to vnic0 and Bridged Networking uses the same address range as Host-only.

Hopefully using the Restore Defaults button will fix the vnic address ranges for you.
 

Attachments

  • Add Adapter.png
    Add Adapter.png
    147.3 KB · Views: 21
Starting Over

I guess my incessant tweaking of network settings caused my CentOS kernel to become overly confused, which resulted in an unrecoverable kernel panic at startup. So now I am back to square one: a new install of CentOS, a fresh install of Oracle, updating my database, installing the software I need to demo, and all that.

First, I need to get back to the point where I was before I originally posted: A stable and persistent demo environment while connected to my home network. I guess after that I'll be asking how to remain "networked" when I'm sitting in a client's office using my laptop to demo...

Thanks.
 
You must log in or register to reply here.
Back
Top