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squalou
Asked: 2018-05-18 04:11:51 +0800 CST

18.04 VPN l2tp issue - connects but no access to resources

  • 772

My network setup is somewhat complex, so let's explain it.

But first keep in mind that everything works perfectly with ubuntu 16.04, nixOs, several flavours of Arch based distribs, and windows 10.

here it is :

[HOME NETWORK] <--l2tp-ipsec-VPN---> [OFFICE NETWORK - with a DNS] <---Site2SiteVPN----> [some other cloud resource]

Expected result example :

  • establish vpn connection from home to office
  • acquire an IP in the expected range (172. instead of 192..., )
  • obtain a correct DNS config
  • SSH or HTTPS to "some other cloud resource" => SHOULD work

On Ubuntu 18.04 :

sudo apt-get install network-manager-l2tp-gnome

then configure connexion, connect : Yeah ! the 'lock' appears near the network icon. Looks promising so far.

A new interface ppp0 appears, with an IP that seems OK

When checking 'whatsmyip.org' it now displays my office IP. Looks fine

ip addr
...
...
12: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1400 qdisc fq_codel state UNKNOWN group default qlen 3
  link/ppp
  inet 172.x.x.x peer 172.255.255.0/32 scope global ppp0

Now here is the issue : - impossible to reach any resource on "some other cloud resource"

http connecion times out, ssh does never answer. ...

I saw this issue on 3 different PCs, from 2 different locations. All of them used to work with 16.04.

Connexion IS established, no error appear on vpn server, or on networkmanager logs, but it's as if all connexions were not using the ppp0 interface.

Made me think of some kind on 'connexion priority' but I didn't find any way to play with that.

Any suggestion would be highly welcome.

Thanks!

PS : I also checked with 'route' command : ppp0 appears with top priority

vpn 18.04 ipsec

2 Answers

  1. I've seen settings that help. Your mileage may vary but ... working in my situation on 18.04.1 and derivates.

    • replace strongswan by libreswan
    sudo apt-get install libreswan
    • don't use systemd-resolved :
    sudo systemctl disable systemd-resolved.service
sudo service systemd-resolved stop

sudo nano /etc/NetworkManager/NetworkManager.conf
[main]
# add this line : 
dns=default
    • restart network-manager
    sudo rm /etc/resolv.conf
sudo service network-manager restart
    • 3
  2. Best Answer

    Go to Edit Connections and select your VPN to edit it. Select the IPv4 settings. Change the "Method" field from "automatic (VPN)" to "Only automatic directions (VPN)"

    It worked for me (Lubuntu 1804)

    • 0