IP route disappears after a few seconds of traffic

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Aaroona

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#195617 26-Apr-2016 21:25

I am currently setting up a small vpn tunnel, which is then connecting 2 LAN's together, for nothing other than helping me understand routing, forwarding, etc.

I have turned an ubuntu host on the destination network into the VPN host and router.

Net1: 172.16.1.0/24

VPN: 192.168.0.0/24

Net2: 192.168.15.0/24

on the VPN host, I have added a route using this command to allow traffic to travel back to Net1;

ip route add 172.16.1.0/24 dev ppp0

I can then ping, browse, do whatever I want across the two LAN's.

So I open VMWare to connect to ESXi- it connects to the server, then stops responding. When I go to check the VPN host, I see that the route that I added just above has disappeared.
This happens all the time and I'm really getting to the end of my tether with it - I cannot work out for the life of me why it disappears.

To be clear; I am not rebooting when this happens - it disappears mid transport of traffic.

Anyone else experienced this issue?

EDIT: here is the route print.

root@ubuntu-ThinkPad:~# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default srp527w 0.0.0.0 UG 0 0 0 wlan0
172.16.1.0 * 255.255.255.0 U 0 0 0 ppp0
192.168.0.234 * 255.255.255.255 UH 0 0 0 ppp0
192.168.15.0 * 255.255.255.0 U 9 0 0 wlan0

After it randomly disappears:
root@ubuntu-ThinkPad:~# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
default srp527w 0.0.0.0 UG 0 0 0 wlan0
192.168.0.234 * 255.255.255.255 UH 0 0 0 ppp0
192.168.15.0 * 255.255.255.0 U 9 0 0 wlan0
root@ubuntu-ThinkPad:~#

MadEngineer

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#1542478 26-Apr-2016 22:37

is vmware's network config conflicting with the vpn?

You're not on Atlantis anymore, Duncan Idaho.

danfaulknor

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Prodigi

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#1542551 27-Apr-2016 08:09

Have you confirmed that the VPN is staying up? Routes vanish when interfaces go away.

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Aaroona

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#1542723 27-Apr-2016 12:36

MadEngineer:

is vmware's network config conflicting with the vpn?

Nope, the VPN box is physical, so can't be a conflict.

danielfaulknor:

Have you confirmed that the VPN is staying up? Routes vanish when interfaces go away.

You're 100% on the money. I was looking through the logs last night after posting, and I can see a Signal 15 being received on the Net1 router. A little digging around seems to indicate that this may be a known issue with the pptpd/pppd daemon, which is frustrating.

Going to do some more testing tonight to see what I can do.

How come we can't set persistent routes? I don't care if traffic gets dropped when the route is down. They're private IP's anyway, so there's no where else for them to go, since they're not internet route-able or anything.

I wonder if I should set up a interface for ppp0 on the VPN server, that way the interface is always there, so the route shouldn't disappear. Will give it a try.

Aaroona

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#1544888 1-May-2016 14:40

I still haven't found the reason why the connection keeps dropping out, however, I have put a script into the /etc/ppp/if-up.d/ folder, which executes when the connection comes up - this automatically adds the route in.

So at least now I'm not losing the route entirely, needing manual intervention, but still dropping some packets when the route goes down temporarily.