Questions tagged [tun]

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What does ip addr add dev tun1 local 192.168.69.0 remote 192.168.69.1 mean?

I found the following set of commands to open a tun device on linux that relays things to the internet. However, packets are not relayed back to the tun device ip tuntap add dev tun1 mode tun user `id ...
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Forwarding Traffic from TUN interface to XX

My setup is the following: I'm writing a program that creates a tun interface and writes raw (Layer 3) packets to that interface. For example a ICMP ping packet (to make things easy). Now i want to ...
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1answer
34 views

Name resolution for dummy interfaces

I've a virtual NIC of type NAT on my Ubuntu 20.04 virtual machine which connects it to the internet via host. For some processing, I need to route all incoming and outgoing packets via a program I've ...
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Can point-to-point TUN interfaces have different MTU?

I'm developing a custom VPN server for Linux. On the server side I set MTU of created tun interface to 1480 using ifconfig tun0 mtu 1480. And, on the client side (Android phone) also MTU of tun set to ...
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1answer
202 views

Route all traffic through TUN interface

I want all my traffic go through TUN interface. So, as you can see, the traffic is routed to TUN iface on 10.0.0.1 address from every program. Then, the program attached to the TUN does something ...
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Is there a tool I can use to test out multiple vpn tunnels in one machine?

I use wget -q -O https://checkmyip.com/csv to determine if I am connected to a VPN but I want to verify multiple VPN tunnels on the same machine. Is there a tool that can allow me to send a command ...
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36 views

How to forward a localhost port to tun device?

I have set up multiple VPN clients on tun devices (tun0, tun1, etc.). I specifically use each device as curl --interface tun1 https://google.com How can I forward specific ports to target tun devices ...
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235 views

Attach a VM to a host TAP or TUN device

I'm working on a project whilst in lockdown in England, and I am hoping someone can offer some advice? I have a machine with 5 physical eth interfaces on Linux Mint, 20.04. All eth interfaces ...
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Unable to enable GSO on tun interface

On my Debian 10 I've got the following interfaces: eth0 tun-test My goal is to enable generic segmentation offload on my tun-test. When using ethtool if fails with Could not change any device ...
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How to migrate OpenVPN architecture TAP to TUN

I did a tunnel system with OpenVPN to let a distant client act like a private network client to access private resources. It uses a client on the private network as a gateway. DistantClient <-> ...
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1answer
608 views

Unable to connect VPN client to OpenVPN server running Ubuntu 16.04.6

im a bit new to Linux and also rather stuck with this... any help here would be much appreciated... I am running Ubuntu 16.0.4 on my server and trying to connect a client to it but no luck. The ...
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4k views

OpenVPN: Cannot open TUN/TAP dev /dev/net/tun: Operation not permitted

I'm have some trouble with OpenVPN reccently, OpenVPN server are hosted on a VPS. It had been work for few months but last friday I reboot and update and upgrade since impossible to connect from my PC ...
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60 views

Embedding 3 bytes custom data in IPv4 header and then filter by iptables

In my modified OpenVPN server process, as an intermediate node, I'd need to embed my custom 3 bytes data in the header of every IP packet and then in the same machine (after going through tun) filter ...
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1answer
832 views

tun/tap works on incoming or outgoing packet?

When we create a tun virtual interface we use read and write to read and write packets from/into network stack. My question is when we use .read, we are actually reading outgoing packets (the packets ...
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1answer
157 views

what is difference between simple TUN and VPNs like PPTP and L2TP

In respect of VPNs and tunneling, as far as i know, TUN is a virtual interface works on network Layer 3 (IP packets), and is nothing more than a simple more likely UDP socket link in practice (I think)...
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471 views

socat tun device very low throughput

I was tinkering around with socat and tried to use socat for creating a TUN device for tunneling between two debian stretch servers. However, throughput seemed very low and comparing with iperf ...
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0answers
725 views

write into a tun interface and forward traffic to another computer

I have the following setup. An application on machine A creates an IP packet which is captured by the tun1 interface. I have added the route using the command : sudo route add -host 10.129.131.220 ...
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2answers
9k views

OpenVPN persist-tun option - what's the point?

According the OpenVPN 2 Cookbook: The persist-tun and persist-key options are used to ensure that the connection comes back up automatically if the underlying network is disrupted. These ...
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1answer
1k views

Multiqueue tun/tap interface

I am trying to understand how Multiqueue tuntap interface works. Following the instructions provided at: https://www.kernel.org/doc/Documentation/networking/tuntap.txt I was able to create multiple ...
2
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1answer
752 views

IPv6 on Linux tun/tap: NDP not working

I am working on an old code that used to connect different IPv6 devices over a different kind of network (a powe line netwrok, PLC, which is quite similar to 802.15.4). To do that, it created Linux ...
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1answer
4k views

OpenVPN TAP vs TUN in parallel

I have a few questions about our existing OpenVPN server setup and a requirement that we have to expand our access. Our current setup is as follows: 1 OpenVPN server (in TAP mode) Multiple VM ...
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1answer
1k views

How to set up single client TAP/TUN on the client for my OpenVPN?

My laptop OpenVPN client establishes a TAP device. My client config is TUN, though. This devices shows under ifconfig /ALL with the IP 10.8.0.6 and a subnetmask of 255.255.255.252. (!!!) This ...
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1answer
2k views

Can the inet address assigned to P-t-P tun interface be used for a client inet address if the server runs out of all addresses within a subnet?

I have an OpenVPN server with an Inet address 10.8.0.1 serving the subnet 10.8.0.0/24. I have two clients connected to this server and the status log (/etc/openvpn/openvpn-status.log)reads as follows: ...
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1answer
2k views

Issues setting up TINC on Mac OSX 10.12.2

I have TINC setup on a few linux boxes and they are working great. linux001 (static ip vps - 10.0.0.1) macosx002 (connects to linux001 - 10.0.0.2) linux050 (connects to linux001 - 10.0.0.50) I also ...
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1answer
165 views

OpenVPN allows some users to jump to other hosts in the LAN

All users can connect to host where OpenVPN runs but some users can jump to other hosts in the LAN. For example, foo user can reach host 10.2.0.1/32 (where OpenVPN runs) and hosts at 10.0.0.0/24 but ...
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1answer
2k views

openvpn - Why do I have 2 tun interfaces on my server?

I have just configured watching this Hak5 video I found on Youtube. But what is bothering me is that why do I have two tun interfaces on my server ? Namely-: tun0 Link encap:UNSPEC HWaddr 00-...
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1answer
307 views

Why is my host not receiving packets sent across tun0?

I have a tun0 interface set up which allows packets to be sent as such: HOST (aaaa::1) ----> tun0 ----> SLIP ----> Router (aaaa::200:0:0:1) The router receives the packets, and can send back a ...
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1answer
1k views

How do I route traffic over the a tun0 device (IPSec VPN connection)?

I've set up an IPSec VPN tunnel between my laptop and work. The tunnel gets established, but routing does not. The relevant part of ifconfig is : eth0 Link encap:Ethernet HWaddr d4:be:d9:6f:a7:...
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1answer
32 views

Endpoint to security gateway tunnel

I want to establish a connection between the client and the proxy server through a VPN tunnel in android device. I want to do this at layer 2 or 3 , where a packet can captured and encrypted. Please ...
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3answers
567 views

How do VPN servers/clients avoid routing their own remote connection packets through themself?

I am trying to conceptualise how networking works under the hood for linux VPNs which use TUN interfaces. My current best guess is as follows (please correct me): Connection established to remote ...
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0answers
644 views

Direct all traffic between Eth0:1 interface and VPN Tun0

If answered correctly this question will show you how to link a 2nd public IP address on a machine to a VPN server tunnel on that machine, so that the remote VPN client (running a server), sees this ...
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1answer
310 views

OpenVPN - connect server as client to itself

I have tried to setup a small openvpn network but I ran into one big problem. I have a server and a machine at home. So I created a openvpn server on my machine and a configured the client on the ...
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1answer
1k views

Prevent IP Spoofing on OpenVPN tun

I have a question regarding IP Spoofing and authentication. I have an OpenVPN server in TUN mode with many untrusted clients in the same VPN network, and I was wondering if one client is able to spoof ...
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1answer
835 views

/dev/net/tun exists, but OpenVPN is refussing to find it

I'm currently configuring an OpenVPN client on an arm microprocessor running debian squeeze, however I'm running into problems. As the below shows, /dev/net/tun exists: debarm:~# whoami root debarm:~...
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1answer
10k views

How to create /dev/tun device inside unprivileged LXC container?

This question is similar to No tun device in lxc guest for openvpn . The LXC has evolved and the unprivileged LXC containers were introduced recently that offer another layer of security against ...
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1answer
5k views

What exactly happens to packets written to a TUN/TAP device?

I'm trying to send packets to an application listening on eth0 from machine's user-space as if they were coming from a remote machine. What I can't seem to find good documentation for is the exact ...
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OpenVPN tunnel not able to support secure connect request

In CentOS 7 host we have installed openvpn package and did create an tunnel using OpenVPN tunneling for eth9 and tap9. Everthing work fine for unsecure connection but when we try to connect to server ...
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2answers
1k views

Use OpenVPN tun device for specific request

I have setup an OpenVPN connection with the route-nopull configuration. So now no special routes have been added to the client's configuration and only a TUN device is created, like so: tun0 ...
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1answer
168 views

Setup openvpn as interface device only

I just setup OpenVPN client using this guide on The Geek Stuff But now (somewhat as expected) all my traffic is routed through the VPN. I actually just want to set up the interface device. Does ...
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2answers
3k views

OpenVPN Tunnel between two LANs, traffic dropped on the way?

I'd like to create a OpenVPN Tunnel between to LANs 192.168.1.0/24 and 192.168.2.0/24. However somehow packets entering the tunnel on one side don't come out of the other side ... The following ...
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2answers
4k views

openvpn connection has established but cant ping the server

I have a openvz vps and setup a openvpn server, and I successfully connect to the server in my ubuntu 14.10 client. server.conf: port 1199 proto udp dev tun ca ca.crt cert server.crt key server.key ...
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1answer
613 views

TCP RST from telnet/ssh daemons when connecting from openvpn

I have LAN_1 and LAN_2 interconnected with an openvpn tunnel terminated ona pair of SOHO routers running busybox. One of the vpn purpose is to allow clients on both LAN_1 and LAN_2, to administer the ...
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0answers
540 views

TUN/TAP VPN no internet connection

I have set up a tun/tap vpn to a VPS. For this, I created a 10/24 network and gave the server the IP 10.0.0.100 and my client got 10.0.0.200. I can now successfully ping the server / access my mail ...
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1answer
12k views

iptables: access connected openvpn client from the LAN with the VPN server

I have what is essentially a routing problem, and I'm not familiar enough with routing and iptables to effectively troubleshoot and set up my network needs. What's working I have an openVPN network ...
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1answer
4k views

How to make Tun module running at linux start

i installed Tun using: modprobe tun then did: lsmod | grep tun tun 83840 0 Please how to make Tun running at reboot? This is written on Hamachi website: ...Then add tun to ...
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1answer
760 views

Unbridged tap device

Good UTC evening! I've created a tap0 device on my host, it looks like: tap0: flags=4099<UP,BROADCAST,MULTICAST> mtu 1500 inet 10.0.0.1 netmask 255.255.255.0 broadcast 10.0.0.255 ...
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1answer
520 views

bridge on openVPN client

I have some problem with setting up what i call a "remote entry point" (i'm sure ther is a real name for this) First things First : Here is my setup : ||==============================================...
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1answer
861 views

Is there a way to allow specific permissions to a non-root user?

I have a program that, at some point, create/destroys tun/tap virtual adapters. Obviously, for these specific operations this program requires root privileges. According to the program ...
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1answer
507 views

Where is the userspace used by TUN/TAP?

When I put data on a wire in qemu what sets the upper limit on the rate of data I can transmit? The situation is I set up two machines A and B create two tap interfaces openvpn --mktun --...
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1answer
3k views

Simple iptables port forwarding with masquerading not working

I'm trying to set up a simple VPN server on EC2 (Ubuntu 12.04) with the Android example ToyVpnServer. Its instructions: // There are several ways to play with this program. Here we just give an // ...