First of all, I'm not familiar with most of the Linux terms, so I apologize in advance.I have Debian 8.0.0-64 running on my server, which has eth1 as interface with the default gateway. eth0 is pointing to the internal network.root@server:/home/user# ifconfigeth0      Link encap:Ethernet  HWaddr 06:46:7e:88:72:d7            inet addr:10.168.118.205  Bcast:10.168.118.255  Mask:255.255.255.192          inet6 addr: fe80::446:7eff:fe88:72d7/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:161 errors:0 dropped:0 overruns:0 frame:0          TX packets:203 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:15215 (14.8 KiB)  TX bytes:79027 (77.1 KiB)eth1      Link encap:Ethernet  HWaddr 06:70:65:5f:e9:89            inet addr:167.41.133.218  Bcast:167.41.133.223  Mask:255.255.255.240          inet6 addr: fe80::470:65ff:fe5f:e989/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:697 errors:0 dropped:0 overruns:0 frame:0          TX packets:282 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:46420 (45.3 KiB)  TX bytes:33486 (32.7 KiB)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:65536  Metric:1          RX packets:706 errors:0 dropped:0 overruns:0 frame:0          TX packets:706 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:86847 (84.8 KiB)  TX bytes:86847 (84.8 KiB)I set up a VPN (TotalVPN) using the following instructions:http://pptpclient.sourceforge.net/howto-debian.phtml#configure_by_handWith pon amsterdam I can actually open a tunnel:root@server:/home/user# pon amsterdamroot@server:/home/user# ifconfigppp0      Link encap:Point-to-Point Protocol            inet addr:10.126.0.29  P-t-P:10.126.0.1  Mask:255.255.255.255          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1496  Metric:1          RX packets:6 errors:0 dropped:0 overruns:0 frame:0          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:3           RX bytes:60 (60.0 B)  TX bytes:66 (66.0 B)So far so good, now I'd love to be able to ping, e.g., google.com (ping -I ppp0 google.com)  through the tunnel, without losing the possibility to use eth1 as my default interface (ping google.com). How can I setup a route or whatever needed, so that traffic (to the internet) can be going through the tunnel, if specifically asked for, i.e., by defining the interface ppp0 to be used.Here are some information (the name of the VPN connection is amsterdam):root@server:/home/user# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         167.41.133.209  0.0.0.0         UG    0      0        0 eth110.0.0.0        10.168.118.193  255.0.0.0       UG    0      0        0 eth010.168.118.192  0.0.0.0         255.255.255.192 U     0      0        0 eth0161.26.0.0      10.168.118.193  255.255.0.0     UG    0      0        0 eth0167.41.133.208  0.0.0.0         255.255.255.240 U     0      0        0 eth1root@server:/home/user# pon amsterdamroot@server:/home/user# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0           0.0.0.0         UG    0      0        0 eth110.0.0.0        10.168.118.193  255.0.0.0       UG    0      0        0 eth010.126.0.1      0.0.0.0         255.255.255.255 UH    0      0        0 ppp010.168.118.192  0.0.0.0         255.255.255.192 U     0      0        0 eth045.32.239.20    167.41.133.209  255.255.255.255 UGH   0      0        0 eth1161.26.0.0      10.168.118.193  255.255.0.0     UG    0      0        0 eth0167.41.133.208  0.0.0.0         255.255.255.240 U     0      0        0 eth1root@server:/home/user# poff amsterdamroot@server:/home/user# route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         167.41.133.209  0.0.0.0         UG    0      0        0 eth110.0.0.0        10.168.118.193  255.0.0.0       UG    0      0        0 eth010.168.118.192  0.0.0.0         255.255.255.192 U     0      0        0 eth045.32.239.20    167.41.133.209  255.255.255.255 UGH   0      0        0 eth1161.26.0.0      10.168.118.193  255.255.0.0     UG    0      0        0 eth0167.41.133.208  0.0.0.0         255.255.255.240 U     0      0        0 eth1root@server:/home/user# Thanks for any help, if you need any more information, please don't hesitate to ask!UPDATESo I found two solutions, which worked on the first view, but really don't work (and I don't know why).Adding route add default metric 10 gw $PPP_REMOTE $PPP_IFNAME in the up-script, oradd defaultroute to the pptp configurationIn both cases, calling curl --interface ppp0 ifconfig.co as root works and returns the ip of the vpn, but I cannot execute the command as any other non-root user. The command curl --interface eth1 ifconfig.co works fine as root or normal user.
Enabling Internet-Route through ppp0
vpn;route;pptp
To achieve what I wanted to achieve I had to do the following things:Step 1: Install the PPTP Client Program for Debian ProjectStep 2: Setup the PPTP connectionStep 3: Testing the connectionStep 4: Adding the routeStep 5: Final checkFor the first three steps, I mainly followed http://pptpclient.sourceforge.net/howto-debian.phtml. After doing so, I found this great article (https://www.thomas-krenn.com/en/wiki/Two_Default_Gateways_on_One_System), which explains on how to add two default gateways. The main idea behind the second gateway approach, is to create a Second Routing Table in /etc/iproute2/rt_tables (in my case I named it ppp). After this is done, routes are added to this new table and rules are defined:ip route add 10.10.0.0/24 dev eth1 src 10.10.0.10 table pppip route add default via 10.10.0.1 dev eth1 table pppip rule add from 10.10.0.10/32 table pppip rule add to 10.10.0.10/32 table pppAfter testing, I added the scripts, so that the routes are added and deleted whenever the VPN connection is established, i.e.,ip-up script#!/bin/shif [ $PPP_IPPARAM = amsterdam ] ; then  /sbin/ip route add $PPP_LOCAL/24 dev $PPP_IFACE src $PPP_LOCAL table ppp  /sbin/ip route add default via $PPP_REMOTE dev $PPP_IFACE table ppp  /sbin/ip rule add from $PPP_LOCAL/32 table ppp  /sbin/ip rule add to $PPP_LOCAL/32 table pppfiip-down script#!/bin/shif [ $PPP_IPPARAM = amsterdam ] ; then  /sbin/ip route del $PPP_LOCAL/24 dev $PPP_IFACE src $PPP_LOCAL table ppp  /sbin/ip route del default via $PPP_REMOTE dev $PPP_IFACE table ppp  /sbin/ip rule del from $PPP_LOCAL/32 table ppp  /sbin/ip rule del to $PPP_LOCAL/32 table pppfiThat works perfectly and I'm able to pick the second gateway whenever needed.