# PPTP VPN over Mobile Broadband Connection

## gus.j.power

Hi,

I'm currently using a Vodafone K3805-Z USB mobile broadband device. 

I've got a /dev/ttyACM0 thanks to usb_modeswitch and /etc/init.d/net.ppp0 connects fine. 

My question is this - how can I setup a PPTP VPN over this connection? 

I've got a working PPTP VPN configuration where I can connect from my home LAN with no problems.

/etc/conf.d/net.ppp1 reads as follows:

```

config_ppp1=( "ppp" )

link_ppp1="pty \"pptp energylab --nolaunchpppd\""

pppd_ppp1=(

         "persist"

         "call energylab"

         "holdoff 10"

         "mru 1460"

         "mtu 1460"

         "idle 600"

)

```

and /etc/ppp/peers/energylab looks like:

```

pty "pptp xxx.xxx.xxx.xxx --nolaunchpppd"

noauth

nobsdcomp

nodeflate

name xxxxxx

remotename energylab

ipparam energylab

require-mppe-128

chap-restart 20

```

However when I bring up ppp1 when ppp0 is active the VPN does not connect and I see alot of the following output:

```

Nov 16 22:14:06 spinship pppd[18206]: rcvd [LCP ConfReq id=0x1 <mru 1450> <asyncmap 0x0> <auth chap MS-v2> <magic 0xxxxxxxx> <pcomp> <accomp>]

Nov 16 22:14:06 spinship pppd[18206]: sent [LCP ConfAck id=0x1 <mru 1450> <asyncmap 0x0> <auth chap MS-v2> <magic 0xxxxxxxx> <pcomp> <accomp>]

Nov 16 22:14:08 spinship pppd[18206]: sent [LCP ConfReq id=0x1 <mru 1460> <asyncmap 0x0> <magic 0xxxxxxxx> <pcomp> <accomp>]

Nov 16 22:14:09 spinship pppd[18206]: rcvd [LCP ConfReq id=0x1 <mru 1450> <asyncmap 0x0> <auth chap MS-v2> <magic 0xxxxxxxx> <pcomp> <accomp>]

Nov 16 22:14:09 spinship pppd[18206]: sent [LCP ConfAck id=0x1 <mru 1450> <asyncmap 0x0> <auth chap MS-v2> <magic 0xxxxxxxx> <pcomp> <accomp>]

Nov 16 22:14:11 spinship pppd[18206]: sent [LCP ConfReq id=0x1 <mru 1460> <asyncmap 0x0> <magic 0xxxxxxxx> <pcomp> <accomp>]

Nov 16 22:14:12 spinship pppd[18206]: rcvd [LCP ConfReq id=0x1 <mru 1450> <asyncmap 0x0> <auth chap MS-v2> <magic 0xxxxxxxx> <pcomp> <accomp>]

```

Normally when connecting successfully I'd see a few lines of ConfReq/Ack chatter and then something like the following:

```

Nov 16 22:15:09 spinship pppd[20624]: rcvd [LCP EchoReq id=0x0 magic=0xxxxxxxx]

Nov 16 22:15:09 spinship pppd[20624]: sent [LCP EchoRep id=0x0 magic=0xxxxxxxx]

Nov 16 22:15:09 spinship pppd[20624]: rcvd [CHAP Challenge id=0x2e <xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, name = "x"]

Nov 16 22:15:09 spinship pppd[20624]: sent [CHAP Response id=0x2e <xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, name = "xxxxxxx"]

Nov 16 22:15:09 spinship pppd[20624]: rcvd [CHAP Success id=0x2e "S=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx M=Access granted"]

```

but this doesn't happen over the Mobile Broadband connection.

Can anyone give me some pointers as to where to go next? 

I'm wondering if there is something in Vodafone's mobile broadband setup that is blocking GRE connections or perhaps it might be that their NAT setup is causing some issues.

Any help greatly appreciated!

Gus

----------

## chithanh

Often on mobile broadband connections users are facing so-called "carrier grade NAT", so they don't have a public IP address. Depending on the configuration of the NAT device, it may also not allow GRE. With some carriers you can request to have NAT disabled and a public IP address assigned to you at not extra charge.

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