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4.1 Configuration introduction | ||
4.2 Multiple networks | ||
4.3 How connections work | ||
4.4 Configuration files | ||
4.5 Generating keypairs | ||
4.6 Network interfaces | ||
4.7 Example configuration |
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Before actually starting to configure tinc and editing files, make sure you have read this entire section so you know what to expect. Then, make it clear to yourself how you want to organize your VPN: What are the nodes (computers running tinc)? What IP addresses/subnets do they have? What is the network mask of the entire VPN? Do you need special firewall rules? Do you have to set up masquerading or forwarding rules? Do you want to run tinc in router mode or switch mode? These questions can only be answered by yourself, you will not find the answers in this documentation. Make sure you have an adequate understanding of networks in general. A good resource on networking is the Linux Network Administrators Guide.
If you have everything clearly pictured in your mind, proceed in the following order: First, generate the configuration files (`tinc.conf', your host configuration file, `tinc-up' and perhaps `tinc-down'). Then generate the keypairs. Finally, distribute the host configuration files. These steps are described in the subsections below.
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In order to allow you to run more than one tinc daemon on one computer, for instance if your computer is part of more than one VPN, you can assign a netname to your VPN. It is not required if you only run one tinc daemon, it doesn't even have to be the same on all the sites of your VPN, but it is recommended that you choose one anyway.
We will asume you use a netname throughout this document. This means that you call tincd with the -n argument, which will assign a netname to this daemon.
The effect of this is that the daemon will set its configuration root to `/etc/tinc/netname/', where netname is your argument to the -n option. You'll notice that it appears in syslog as `tinc.netname'.
However, it is not strictly necessary that you call tinc with the -n option. In this case, the network name would just be empty, and it will be used as such. tinc now looks for files in `/etc/tinc/', instead of `/etc/tinc/netname/'; the configuration file should be `/etc/tinc/tinc.conf', and the host configuration files are now expected to be in `/etc/tinc/hosts/'.
But it is highly recommended that you use this feature of tinc, because it will be so much clearer whom your daemon talks to. Hence, we will assume that you use it.
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When tinc starts up, it parses the command-line options and then reads in the configuration file tinc.conf. If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file, it will try to connect to those other daemons. Whether this succeeds or not and whether `ConnectTo' is specified or not, tinc will listen for incoming connection from other deamons. If you did specify a `ConnectTo' value and the other side is not responding, tinc will keep retrying. This means that once started, tinc will stay running until you tell it to stop, and failures to connect to other tinc daemons will not stop your tinc daemon for trying again later. This means you don't have to intervene if there are temporary network problems.
There is no real distinction between a server and a client in tinc. If you wish, you can view a tinc daemon without a `ConnectTo' value as a server, and one which does specify such a value as a client. It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
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The actual configuration of the daemon is done in the file `/etc/tinc/netname/tinc.conf' and at least one other file in the directory `/etc/tinc/netname/hosts/'.
These file consists of comments (lines started with a #) or assignments in the form of
Variable = Value. |
The variable names are case insensitive, and any spaces, tabs, newlines and carriage returns are ignored. Note: it is not required that you put in the `=' sign, but doing so improves readability. If you leave it out, remember to replace it with at least one space character.
In this section all valid variables are listed in alphabetical order. The default value is given between parentheses, other comments are between square brackets.
4.4.1 Main configuration variables | ||
4.4.2 Host configuration variables | ||
4.4.3 Scripts | ||
4.4.4 How to configure |
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This option may not work on all platforms.
This option may not work on all platforms.
If you don't specify a host with ConnectTo, tinc won't try to connect to other daemons at all, and will instead just listen for incoming connections.
This does not affect resolving hostnames to IP addresses from the configuration file.
This is the default mode, and unless you really know you need another mode, don't change it.
This mode is primarily useful if you want to bridge Ethernet segments.
Note that there must be exactly one of PrivateKey or PrivateKeyFile specified in the configuration file.
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From version 1.0pre4 on tinc will store the public key directly into the host configuration file in PEM format, the above two options then are not necessary. Either the PEM format is used, or exactly one of the above two options must be specified in each host configuration file, if you want to be able to establish a connection with that host.
Subnets can either be single MAC, IPv4 or IPv6 addresses, in which case a subnet consisting of only that single address is assumed, or they can be a IPv4 or IPv6 network address with a prefixlength. Shorthand notations are not supported. For example, IPv4 subnets must be in a form like 192.168.1.0/24, where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask. Note that subnets like 192.168.1.1/24 are invalid! Read a networking HOWTO/FAQ/guide if you don't understand this. IPv6 subnets are notated like fec0:0:0:1:0:0:0:0/64. MAC addresses are notated like 0:1a:2b:3c:4d:5e.
Prefixlength is the number of bits set to 1 in the netmask part; for example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes /22. This conforms to standard CIDR notation as described in RFC1519
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Apart from reading the server and host configuration files, tinc can also run scripts at certain moments. Under Windows (not Cygwin), the scripts should have the extension .bat.
The scripts are started without command line arguments, but can make use of certain environment variables. Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts. Under Windows, in `.bat' files, they have to be put between % signs.
NETNAME
NAME
DEVICE
INTERFACE
NODE
REMOTEADDRESS
REMOTEPORT
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The main configuration file will be called `/etc/tinc/netname/tinc.conf'. Adapt the following example to create a basic configuration file:
Name = yourname Device = `/dev/tap0' |
Then, if you know to which other tinc daemon(s) yours is going to connect, add `ConnectTo' values.
If you added a line containing `Name = yourname' in the main configuarion file, you will need to create a host configuration file `/etc/tinc/netname/hosts/yourname'. Adapt the following example to create a host configuration file:
Address = your.real.hostname.org Subnet = 192.168.1.0/24 |
You can also use an IP address instead of a hostname. The `Subnet' specifies the address range that is local for your part of the VPN only. If you have multiple address ranges you can specify more than one `Subnet'. You might also need to add a `Port' if you want your tinc daemon to run on a different port number than the default (655).
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Now that you have already created the main configuration file and your host configuration file, you can easily create a public/private keypair by entering the following command:
tincd -n netname -K |
Tinc will generate a public and a private key and ask you where to put them. Just press enter to accept the defaults.
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Before tinc can start transmitting data over the tunnel, it must set up the virtual network interface.
First, decide which IP addresses you want to have associated with these devices, and what network mask they must have.
Tinc will open a virtual network device (`/dev/tun', `/dev/tap0' or similar), which will also create a network interface called something like `tun0', `tap0'. If you are using the Linux tun/tap driver, the network interface will by default have the same name as the netname. Under Windows you can change the name of the network interface from the Network Connections control panel.
You can configure the network interface by putting ordinary ifconfig, route, and other commands to a script named `/etc/tinc/netname/tinc-up'. When tinc starts, this script will be executed. When tinc exits, it will execute the script named `/etc/tinc/netname/tinc-down', but normally you don't need to create that script.
An example `tinc-up' script:
#!/bin/sh ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0 |
This script gives the interface an IP address and a netmask. The kernel will also automatically add a route to this interface, so normally you don't need to add route commands to the `tinc-up' script. The kernel will also bring the interface up after this command. The netmask is the mask of the entire VPN network, not just your own subnet.
The exact syntax of the ifconfig and route commands differs from platform to platform. You can look up the commands for setting addresses and adding routes in 7. Platform specific information, but it is best to consult the manpages of those utilities on your platform.
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Imagine the following situation. Branch A of our example `company' wants to connect three branch offices in B, C and D using the Internet. All four offices have a 24/7 connection to the Internet.
A is going to serve as the center of the network. B and C will connect to A, and D will connect to C. Each office will be assigned their own IP network, 10.x.0.0.
A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7 |
Here, "gateway" is the VPN IP address of the machine that is running the tincd, and "internet IP" is the IP address of the firewall, which does not need to run tincd, but it must do a port forwarding of TCP and UDP on port 655 (unless otherwise configured).
In this example, it is assumed that eth0 is the interface that points to the inner (physical) LAN of the office, although this could also be the same as the interface that leads to the Internet. The configuration of the real interface is also shown as a comment, to give you an idea of how these example host is set up. All branches use the netname `company' for this particular VPN.
BranchA would be configured like this:
In `/etc/tinc/company/tinc-up':
# Real interface of internal network: # ifconfig eth0 10.1.54.1 netmask 255.255.0.0 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0 |
and in `/etc/tinc/company/tinc.conf':
Name = BranchA Device = /dev/tap0 |
On all hosts, `/etc/tinc/company/hosts/BranchA' contains:
Subnet = 10.1.0.0/16 Address = 1.2.3.4 -----BEGIN RSA PUBLIC KEY----- ... -----END RSA PUBLIC KEY----- |
Note that the IP addresses of eth0 and tap0 are the same. This is quite possible, if you make sure that the netmasks of the interfaces are different. It is in fact recommended to give give both real internal network interfaces and tap interfaces the same IP address, since that will make things a lot easier to remember and set up.
In `/etc/tinc/company/tinc-up':
# Real interface of internal network: # ifconfig eth0 10.2.43.8 netmask 255.255.0.0 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0 |
and in `/etc/tinc/company/tinc.conf':
Name = BranchB ConnectTo = BranchA |
Note here that the internal address (on eth0) doesn't have to be the same as on the tap0 device. Also, ConnectTo is given so that no-one can connect to this node.
On all hosts, in `/etc/tinc/company/hosts/BranchB':
Subnet = 10.2.0.0/16 Address = 2.3.4.5 -----BEGIN RSA PUBLIC KEY----- ... -----END RSA PUBLIC KEY----- |
In `/etc/tinc/company/tinc-up':
# Real interface of internal network: # ifconfig eth0 10.3.69.254 netmask 255.255.0.0 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0 |
and in `/etc/tinc/company/tinc.conf':
Name = BranchC ConnectTo = BranchA Device = /dev/tap1 |
C already has another daemon that runs on port 655, so they have to reserve another port for tinc. It knows the portnumber it has to listen on from it's own host configuration file.
On all hosts, in `/etc/tinc/company/hosts/BranchC':
Address = 3.4.5.6 Subnet = 10.3.0.0/16 Port = 2000 -----BEGIN RSA PUBLIC KEY----- ... -----END RSA PUBLIC KEY----- |
In `/etc/tinc/company/tinc-up':
# Real interface of internal network: # ifconfig eth0 10.4.3.32 netmask 255.255.0.0 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0 |
and in `/etc/tinc/company/tinc.conf':
Name = BranchD ConnectTo = BranchC Device = /dev/net/tun |
D will be connecting to C, which has a tincd running for this network on port 2000. It knows the port number from the host configuration file. Also note that since D uses the tun/tap driver, the network interface will not be called `tun' or `tap0' or something like that, but will have the same name as netname.
On all hosts, in `/etc/tinc/company/hosts/BranchD':
Subnet = 10.4.0.0/16 Address = 4.5.6.7 -----BEGIN RSA PUBLIC KEY----- ... -----END RSA PUBLIC KEY----- |
A, B, C and D all have generated a public/private keypair with the following command:
tincd -n company -K |
The private key is stored in `/etc/tinc/company/rsa_key.priv', the public key is put into the host configuration file in the `/etc/tinc/company/hosts/' directory. During key generation, tinc automatically guesses the right filenames based on the -n option and the Name directive in the `tinc.conf' file (if it is available).
After each branch has finished configuration and they have distributed the host configuration files amongst them, they can start their tinc daemons. They don't necessarily have to wait for the other branches to have started their daemons, tinc will try connecting until they are available.
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