LinuxQuestions.org
Visit Jeremy's Blog.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Networking
User Name
Password
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.

Notices


Reply
  Search this Thread
Old 04-14-2016, 11:25 AM   #1
sundialsvcs
LQ Guru
 
Registered: Feb 2004
Location: SE Tennessee, USA
Distribution: Gentoo, LFS
Posts: 10,649
Blog Entries: 4

Rep: Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935Reputation: 3935
Question Weird OpenVPN problem connecting to VM -- I fixed it, but how?


I have several (VirtualBox ...) VMs running on a remote server, each of which has a Bridged network adapter such that it obtains an IP-address (192.168.1.xxx) on the remote local-network, which address I know.

Ordinarily, I am able to SSH from the remote side directly to this address without difficulty.

However, after doing what I thought was a perfectly ordinary restart of one VM, I found that I could no longer SSH it or ping it! Yet, I could open a Remote Desktop session (over VPN ...) to that server, and, from its desktop, grab a terminal window and either Ping or SSH to the VM as expected.

I of course confirmed that, on my system, a route to the destination address is defined, and that it does go through the VPN tunnel. (That's been working fine for many weeks.)

Curious now, but not yet in a panic, I started Wireshark on that server and tried to ping from my side. I found the packets appearing (at the address corresponding to my VPN connection), being sent to the VM, but "no reply!" I could also see pings from the local session (that I had started using my Remote Desktop) being sent and replied-to. In other words, the VM seemed to be replying to one IP-address but not the other.

Becoming more alarmed by the minute, I opened the console of the VM and looked at its IPTables rules: there were none. This VM does not have any sort of firewall.

Panicking now, I decided to punt: sudo service networking restart.

. . . and, magically, it now works just fine. Now, my pings from the remote side are being replied-to, and I can ssh from the remote. just like I had been able to do before restarting the VM.

Therefore, I am quite flummoxed ... unable to point my finger at "exactly what was the problem," and also, to "why this particular command (albeit: 'thank god it did!') fixed it.

The core symptom seems to be: from the point-of-view of WireShark, running on the remote system (and being accessed by means of VPN, the entire time!), pings to the VM from the VPN-portal addresses were not being replied to. The remote side could not ping this address, although it could ping other (non-VM) IP-addresses (to which it has established routes) without difficulty.

Last edited by sundialsvcs; 04-14-2016 at 11:29 AM.
 
Old 04-16-2016, 04:31 AM   #2
ferrari
LQ Guru
 
Registered: Sep 2003
Location: Auckland, NZ
Distribution: openSUSE Leap
Posts: 5,797

Rep: Reputation: 1140Reputation: 1140Reputation: 1140Reputation: 1140Reputation: 1140Reputation: 1140Reputation: 1140Reputation: 1140Reputation: 1140
If I read this right, you could ping the remote VM guest via the host, but not from your local machine? That reads like a missing default route on the guest at the time. (Since host and guest are on the same subnet, ARP is used.) So, I can see why restarting the guest network might have fixed a 'gateway' issue.
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off



Similar Threads
Thread Thread Starter Forum Replies Last Post
[SOLVED] Problem connecting to openvpn server from ubuntu 10.04 moyorakkhi Linux - Newbie 3 01-18-2012 12:23 AM
Openvpn: connecting from windows client problem blckspder Linux - Networking 0 09-26-2008 08:54 AM
Problem connecting to Openvpn server from Windows computer pankaj_garg Linux - Networking 1 08-04-2007 12:23 PM
OpenVPN Question : connecting 5-6 comps with OpenVPN duryodhan Linux - Networking 7 02-15-2007 10:28 PM
Help!. Problem connecting to an Openvpn through proxy server. microsoftguy Linux - Software 1 08-03-2006 09:54 PM

LinuxQuestions.org > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 05:58 AM.

Main Menu
Advertisement
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Open Source Consulting | Domain Registration