softether TAP interface on unprivileged container not passing to host

rexkani

New Member
May 4, 2019
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Dear all,

I have been trying to follow instructions found on this forum to enable my container to create a TAP device.
i used this on the pve host:

/etc/pve/lxc/102.conf

lxc.cgroup.devices.allow = c 10:200 rwm
lxc.mount.entry = /dev/net/tun dev/net/tun none bind,create=file
i see the TAP device successfully created by softether:

2: tap_soft: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
link/ether 5e:11:6f:f3:8f:db brd ff:ff:ff:ff:ff:ff
inet6 fe80::5c11:6fff:fef3:8fdb/64 scope link
valid_lft forever preferred_lft forever
but when i try to establish a L2TP vpn from a remote host, the remote host traffic cant seem to go to the pve host and DHCP cannot be processed:

2019-05-16 03:03:21.625 On the TCP Listener (Port 0), a Client (IP address xxx.xxx.xxx.xxx, Host name "xxx.xxx.xxx.xxx", Port number 1701) has connected.
2019-05-16 03:03:21.625 For the client (IP address: xxx.xxx.xxx.xxx, host name: "xxx.xxx.xxx.xxx", port number: 1701), connection "CID-1" has been created.
2019-05-16 03:03:21.625 SSL communication for connection "CID-1" has been started. The encryption algorithm name is "(null)".
2019-05-16 03:03:21.625 [HUB "VPN"] The connection "CID-1" (IP address: xxx.xxx.xxx.xxx, Host name: xxx.xxx.xxx.xxx, Port number: 1701, Client name: "L2TP VPN Client", Version: 4.29, Build: 9680) is attempting to connect to the Virtual Hub. The auth type provided is "External server authentication" and the user name is "abc".
2019-05-16 03:03:21.625 [HUB "VPN"] Connection "CID-1": Successfully authenticated as user "abc".
2019-05-16 03:03:21.625 [HUB "VPN"] Connection "CID-1": The new session "SID-abc-[L2TP]-2" has been created. (IP address: xxx.xxx.xxx.xxx, Port number: 1701, Physical underlying protocol: "Legacy VPN - L2TP")
2019-05-16 03:03:21.625 [HUB "VPN"] Session "SID-abc-[L2TP]-2": The parameter has been set. Max number of TCP connections: 1, Use of encryption: Yes, Use of compression: No, Use of Half duplex communication: No, Timeout: 20 seconds.
2019-05-16 03:03:21.625 [HUB "VPN"] Session "SID-abc-[L2TP]-2": VPN Client details: (Client product name: "L2TP VPN Client", Client version: 429, Client build number: 9680, Server product name: "SoftEther VPN Server (64 bit)", Server version: 429, Server build number: 9680, Client OS name: "L2TP VPN Client", Client OS version: "-", Client product ID: "-", Client host name: "anonymous", Client IP address: "xxx.xxx.xxx.xxx", Client port number: 1701, Server host name: "xxx.xxx.xxx.xxx", Server IP address: "xxx.xxx.xxx.xxx", Server port number: 1701, Proxy host name: "", Proxy IP address: "0.0.0.0", Proxy port number: 0, Virtual Hub name: "VPN", Client unique ID: "FC3F68CDF0545A43EC372F364A3BE044")
2019-05-16 03:03:21.685 L2TP PPP Session [xxx.xxx.xxx.xxx:1701]: Trying to request an IP address from the DHCP server.
2019-05-16 03:03:26.687 L2TP PPP Session [xxx.xxx.xxx.xxx:1701]: Acquiring an IP address from the DHCP server failed. To accept a PPP session, you need to have a DHCP server. Make sure that a DHCP server is working normally in the Ethernet segment which the Virtual Hub belongs to. If you do not have a DHCP server, you can use the Virtual DHCP function of the SecureNAT on the Virtual Hub instead.
2019-05-16 03:03:33.368 L2TP PPP Session [xxx.xxx.xxx.xxx:1701]: The VPN Client sent a packet though an IP address of the VPN Client hasn't been determined.
2019-05-16 03:03:33.368 L2TP PPP Session [xxx.xxx.xxx.xxx:1701]: A PPP protocol error occurred, or the PPP session has been disconnected.

Can anyone please help to solve this problem please?
 

rexkani

New Member
May 4, 2019
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Futher looking at my host, I'm not seeing any TAP device on the host, is this going to be an issue?
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
2: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master vmbr0 state UP group default qlen 1000
3: vmbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
5: veth100i0@if4: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
12: veth103i0@if11: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr103i0 state UP group default qlen 1000
13: fwbr103i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
14: fwpr103p0@fwln103i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
15: fwln103i0@fwpr103p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr103i0 state UP group default qlen 1000
17: veth104i0@if16: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr104i0 state UP group default qlen 1000
18: fwbr104i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
19: fwpr104p0@fwln104i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
20: fwln104i0@fwpr104p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr104i0 state UP group default qlen 1000
22: veth105i0@if21: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr105i0 state UP group default qlen 1000
23: fwbr105i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
24: fwpr105p0@fwln105i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
25: fwln105i0@fwpr105p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr105i0 state UP group default qlen 1000
27: veth106i0@if26: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr106i0 state UP group default qlen 1000
28: fwbr106i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
29: fwpr106p0@fwln106i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
30: fwln106i0@fwpr106p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr106i0 state UP group default qlen 1000
32: veth108i0@if31: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr108i0 state UP group default qlen 1000
33: fwbr108i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
34: fwpr108p0@fwln108i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
35: fwln108i0@fwpr108p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr108i0 state UP group default qlen 1000
37: veth102i0@if36: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr102i0 state UP group default qlen 1000
38: fwbr102i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
39: fwpr102p0@fwln102i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
40: fwln102i0@fwpr102p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr102i0 state UP group default qlen 1000
42: veth109i0@if41: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr109i0 state UP group default qlen 1000
43: fwbr109i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
44: fwpr109p0@fwln109i0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master vmbr0 state UP group default qlen 1000
45: fwln109i0@fwpr109p0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master fwbr109i0 state UP group default qlen 1000
 

rexkani

New Member
May 4, 2019
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Therefore, with this showing in my "ip addr", it looks like it should be working?
2: tap_soft: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UNKNOWN group default qlen 1000
link/ether 5e:11:6f:f3:8f:db brd ff:ff:ff:ff:ff:ff
inet6 fe80::5c11:6fff:fef3:8fdb/64 scope link
valid_lft forever preferred_lft forever
is there any other ways i could troubleshoot this issue? i'm kinda stuck on how to further investigate on the issue. i'm not sure where is the problem happening now.
 

rexkani

New Member
May 4, 2019
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can someone help to point me to the direction on how to further investigate please? hope to at least find out if its the host config's or the container config's problem
 

rexkani

New Member
May 4, 2019
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just found this on the softether interface, which shows the mac address learned from the local-bridge, on the local-bridge built on the container's eth0, i can see mac addresses.



but on the local-bridge built on the TAP interface, no mac can be learnt


upload_2019-5-17_11-16-35.png
 

LnxBil

Famous Member
Feb 21, 2015
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Maybe, you need some kernel modules to forward the traffic. IIRC, there was VPN solutions that used GRE. On the other hand, you can always run tcdpump on your PVE and visualize via wireshark. Often, it's the only way to "see" what's going on.
 

rexkani

New Member
May 4, 2019
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I have ran tcpdump on the PVE host and i cannot see any DHCP traffic going out of my physical interface. and then i dont know how to further investigate.
 

LnxBil

Famous Member
Feb 21, 2015
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I have no idea how L2TP works, but for other VPN solutions, I've never seen DHCP on a VPN. The IP configuration is integrated in the connection handshake, so that there is no DHCP. Are you certain that you have and want DHCP over VPN?
 

rexkani

New Member
May 4, 2019
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L2TP/IPsec is a sort of Layer 2 VPN through a secure IPsec tunnel, therefore, the DHCP will be done inside the tunnel.

no matter which tunnel protocol i'm going to run, if no mac addresses can be learnt from the bridge interface, no network connectivity can be established.

it doesnt seem like the guest host is really using the "TAP device" but i have no idea what can be done to solve this...
 

LnxBil

Famous Member
Feb 21, 2015
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L2TP/IPsec is a sort of Layer 2 VPN through a secure IPsec tunnel, therefore, the DHCP will be done inside the tunnel.
Thanks for the explanation. I've only used ipsec inside of qemu-based VMs, so I cannot give any other recommendation except using a "real" VM.
 

rexkani

New Member
May 4, 2019
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thanks for discussing with me.

I hope there are more ideas here from the community could lead me to a solution.
 

rexkani

New Member
May 4, 2019
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hi,
therefore... the softether vpn server should be run in a virtual machine or in a container?
Hi openaspace,

I still cant get it running on unprivileged container yet. i guess there might be a way to fix it but i cant.

sigh.
 

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