Interesting issue with a "wwan0" device as gateway

stark

Hi chaps

I've recently become the proud user of a Lenovo Carbon X1 (2015 model)... one of the perks of this kit was the built-in 4G modem.

So.. this device appears as a "wwan0" and sadly whenever I'm using it I have issues connecting to my VPN.

The same connection works over wifi/ethernet etc so ok..

I'm on ubuntu 14.04+zfs+gnome-shell (FWIW).. seems that the attempt to add a route to my server fails (renamed to 1.2.3.4 in this example)

Sat Oct  3 20:03:05 2015 us=926846 ROUTE_GATEWAY ON_LINK IFACE=wwan0 HWADDR=c6:79:f4:a9:XX:XX
Sat Oct  3 20:03:05 2015 us=927119 TUN/TAP device tun0 opened
Sat Oct  3 20:03:05 2015 us=927142 TUN/TAP TX queue length set to 100
Sat Oct  3 20:03:05 2015 us=927158 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Sat Oct  3 20:03:05 2015 us=927179 /sbin/ip link set dev tun0 up mtu 1500
Sat Oct  3 20:03:05 2015 us=927929 /sbin/ip addr add dev tun0 local 10.8.0.94 peer 10.8.0.93
Sat Oct  3 20:03:05 2015 us=928919 /sbin/ip route add 1.2.3.4/32 via 0.0.0.0
RTNETLINK answers: No such device
Sat Oct  3 20:03:05 2015 us=931207 ERROR: Linux route add command failed: external program exited with error status: 2
Sat Oct  3 20:03:05 2015 us=931337 /sbin/ip route add 0.0.0.0/1 via 10.8.0.93
Sat Oct  3 20:03:05 2015 us=933100 /sbin/ip route add 128.0.0.0/1 via 10.8.0.93
Sat Oct  3 20:03:05 2015 us=934035 /sbin/ip route add 10.8.0.1/32 via 10.8.0.93
Sat Oct  3 20:03:05 2015 us=934775 Initialization Sequence Completed

Heres what that looks like on a regular wlan0 connect:

Sat Oct  3 19:59:24 2015 us=975372 ROUTE_GATEWAY 10.3.0.1/255.255.255.0 IFACE=wlan0 HWADDR=4c:34:88:88:XX:XX
Sat Oct  3 19:59:24 2015 us=975974 TUN/TAP device tun0 opened
Sat Oct  3 19:59:24 2015 us=976004 TUN/TAP TX queue length set to 100
Sat Oct  3 19:59:24 2015 us=976021 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Sat Oct  3 19:59:24 2015 us=976046 /sbin/ip link set dev tun0 up mtu 1500
Sat Oct  3 19:59:24 2015 us=977031 /sbin/ip addr add dev tun0 local 10.8.0.94 peer 10.8.0.93
Sat Oct  3 19:59:24 2015 us=978279 /sbin/ip route add 1.2.3.4/32 via 10.3.0.1
Sat Oct  3 19:59:24 2015 us=979014 /sbin/ip route add 0.0.0.0/1 via 10.8.0.93
Sat Oct  3 19:59:24 2015 us=979707 /sbin/ip route add 128.0.0.0/1 via 10.8.0.93
Sat Oct  3 19:59:24 2015 us=980750 /sbin/ip route add 10.8.0.1/32 via 10.8.0.93
Sat Oct  3 19:59:24 2015 us=981540 Initialization Sequence Completed

Example IPs/routing when on 4g (I am posting through it for meta sake)

chevron :: vpn/srvbit/chevron-uk.vpn.srvbit.com % ip a                                                                                   
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth2: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000
    link/ether 54:ee:75:6f:XX:XX brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 4c:34:88:88:XX:XX brd ff:ff:ff:ff:ff:ff
5: lxcbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default 
    link/ether 22:3c:0e:fe:XX:XX brd ff:ff:ff:ff:ff:ff
    inet 10.0.1.1/24 scope global lxcbr0
       valid_lft forever preferred_lft forever
    inet6 fe80::XXXX:XXX:XXXX:XXXX/64 scope link 
       valid_lft forever preferred_lft forever
46: wwan0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1428 qdisc pfifo_fast state UNKNOWN group default qlen 1000
    link/ether c6:79:f4:a9:XX:XX brd ff:ff:ff:ff:ff:ff
    inet 100.71.21.62/24 brd 100.71.21.255 scope global wwan0
       valid_lft forever preferred_lft forever
    inet6 fe80::c479:f4ff:fea9:44f4/64 scope link 
       valid_lft forever preferred_lft forever

ip r

default dev wwan0  proto static 
10.0.1.0/24 dev lxcbr0  proto kernel  scope link  src 10.0.1.1 
100.71.21.0/24 dev wwan0  proto kernel  scope link  src 100.71.21.62  metric 13

I'm very happy to provide any details you require...

Rgds
-d

Traffic

stark wroteseems that the attempt to add a route to my server fails (renamed to 1.2.3.4 in this example)

to your client in fact ..

stark wroteCode:
Sat Oct 3 20:03:05 2015 us=926846 ROUTE_GATEWAY ON_LINK IFACE=wwan0 HWADDR=c6:79:f4:a9:XX:XX
Sat Oct 3 20:03:05 2015 us=927119 TUN/TAP device tun0 opened
Sat Oct 3 20:03:05 2015 us=927142 TUN/TAP TX queue length set to 100
Sat Oct 3 20:03:05 2015 us=927158 do_ifconfig, tt->ipv6=0, tt->did_ifconfig_ipv6_setup=0
Sat Oct 3 20:03:05 2015 us=927179 /sbin/ip link set dev tun0 up mtu 1500
Sat Oct 3 20:03:05 2015 us=927929 /sbin/ip addr add dev tun0 local 10.8.0.94 peer 10.8.0.93
Sat Oct 3 20:03:05 2015 us=928919 /sbin/ip route add 1.2.3.4/32 via 0.0.0.0
RTNETLINK answers: No such device
Sat Oct 3 20:03:05 2015 us=931207 ERROR: Linux route add command failed: external program exited with error status: 2

Looks like --redirect-gateway has failed to do this correctly ..

stark wroteI'm very happy to provide any details you require...

Server and client configs please 8-)

stark

Surely.. thanks for looking at it.. ye I noticed the routing fail... weird huh? I've literally never experienced an issue with ovpn before to be frank!

Server is a baremetal Centos6 box.. from base repo: "openvpn.i686 2.3.8-1.el6"

Server config:

local 1.2.3.4
port 1194
proto udp
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh2048.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
keepalive 5 30
push "keepalive 5 30"
comp-lzo
user nobody
group nobody
persist-key
persist-tun
status openvpn-status.log
verb 3

Client is the standard ubuntu one .. version: 2.3.2-7ubuntu3.1
Client config (minus keys etc.. follows.. )

client
dev tun
proto udp
remote 1.2.3.4 1194
#ping every 5 seconds, reconnect if no ping for 30 sec:
keepalive 5 30
resolv-retry infinite
nobind
persist-key
persist-tun
comp-lzo
# verb 3
verb 4
# verb 5
<ca>
BLA
</ca>
<cert>
BLABLA
</cert>
<key>
BLABLABLA
</key>

Traffic

Try this, change (server.conf):

stark wrotepush "redirect-gateway def1 bypass-dhcp"

To:

push "redirect-gateway def1"

stark

OK I tried that.. normal connections still work, but still no cigar over wwan0 :/

Traffic

stark wroteSat Oct 3 20:03:05 2015 us=928919 /sbin/ip route add 1.2.3.4/32 via 0.0.0.0
RTNETLINK answers: No such device

It seems OpenVPN is not identifying the default gateway associated with wwan0 interface.

Disable all other interfaces and try again.

To test OpenVPN works on this device, disable --push "redirect-gateway" (in server.conf) for this client and try again. Test the connection by pinging the server.

Please post your complete sanitised log at --verb 4