tayga.conf (5) Linux Manual Page

tayga.conf – configuration file of the TAYGA stateless NAT64 daemon

Description

This file contains the configuration parameters for the TAYGA stateless NAT64 daemon. It must exist and contain the mandatory configuration items or TAYGA will refuse to run. The configuration directives are listed below. With the exception of the map directive, only one instance of each directive may appear in tayga.conf.

tun-device device

Name of the network interface that will be created by the kernel TUN module for TAYGA to exchange IPv4 and IPv6 packets with the in-kernel TCP/IP stack. If device does not already exist as a persistent interface (created by the –mktun flag to tayga(8), for example), it will be created automatically when the TAYGA daemon starts and destroyed when the daemon exits.

Note that TAYGA does not configure the host-side parameters of device. This must be done by the system administrator using the ifconfig(8), route(8), and/or ip(8) commands.

This configuration directive is mandatory.

ipv4-addr ipv4_address

IPv4 address that TAYGA will use as the source address for ICMPv4 errors generated by the translation process. TAYGA will also respond to ICMP echo requests (pings) at this address.

ipv4_address is permitted to overlap with the prefix specified in the dynamic-pool directive, in which case ipv4_address will be removed from the pool of available addresses.

This configuration directive is mandatory.

ipv6-addr ipv6_address

IPv6 address that TAYGA will use as the source address for ICMPv6 errors generated by the translation process. TAYGA will also respond to ICMPv6 echo requests (pings) at this address.

This configuration directive is mandatory unless the NAT64 prefix is specified with the prefix directive, in which case TAYGA will generate its IPv6 address by mapping the address specified in ipv4-addr into the NAT64 prefix.

prefix ipv6_address/length

NAT64 prefix for mapping IPv4 addresses into the IPv6 address space. TAYGA performs address translation as specified in RFC 6052, and only prefix lengths allowed in that document will be permitted in the prefix directive.

The use of either a Network-Specific Prefix or the Well-Known Prefix (64:ff9b::/96) is allowed, however, as required by RFC 6052, TAYGA will refuse to translate packets with a source or destination address composed of the Well-Known Prefix and a non-global IPv4 address (10.x.x.x, 192.168.x.x, etc).

Use of the prefix directive is optional. If it is not specified, all addresses to be translated must be listed individually with the map directive.

map ipv4_address ipv6_address

Creates a static mapping between ipv4_address and ipv6_address to be used when translating IPv4 packets to IPv6 or IPv6 packets to IPv4. Multiple map directives are permitted in the tayga.conf file.

ipv4_address is permitted to overlap with the prefix specified in the dynamic-pool directive, in which case ipv4_address will be removed from the pool of available addresses.

ipv6_address must not overlap with the prefix specified in the prefix directive.

dynamic-pool ipv4_address/length

Address prefix containing addresses available to be assigned to IPv6 hosts. length must be 31 or less, as the lowest-numbered address in the prefix is considered reserved and will not be used for dynamic assignment.

If TAYGA receives an IPv6 packet to be translated with an IPv6 source address that does not match any existing mapping rules (as specified by the map directive or the prefix directive), TAYGA will create a dynamic mapping between the IPv6 address and an IPv4 address drawn from the prefix specified by the dynamic-pool directive. This mapping will be valid for two hours and four minutes after the last packet matching the mapping is translated.

The dynamic-pool directive is optional. If it is not specified, all IPv6 addresses appearing in packets passing through TAYGA must match the NAT64 prefix or a static mapping rule.

data-dir path

The absolute path of a directory where TAYGA should store its data files. Presently the only data file that TAYGA will store is the dynamic.map file, which tracks dynamic address assignments made from the dynamic pool.

path is also the directory that will be used as a chroot(2) "jail" if the –chroot command-line option is specified to the TAYGA daemon.

The TAYGA daemon must have full permissions (rwx) to path after it has dropped superuser privileges. Generally this means that the owner of path should be the user specified in the –user command-line option.

The data-dir directive is optional, but without it, dynamic mappings will be lost when the TAYGA daemon is stopped. Also, use of the –chroot command-line option will not be possible.

strict-frag-hdr on|off|true|false|1|0

Flag to control whether TAYGA adds fragmentation headers to IPv6 packets that do not require fragmentation. RFC 6145 stipulates that the fragmentation header SHOULD be added to all translated packets when the sender has not set the DF (Don’t Fragment) flag, to indicate that the sender allows fragmentation and may not support path MTU discovery. Unfortunately, some firewall implementations drop IPv6 packets that are fragmented into a single fragment, most notably Linux netfilter conntrack in kernels older than 2.6.34.

When strict-frag-hdr is set to true, on, or 1, fragmentation headers will be added to all translated packets where the DF bit in the original packet is clear. This is the RFC-complaint behavior.

When strict-frag-hdr is set to false, off, or 0, fragmentation headers will be suppressed when the translated packet fits entirely within the IPv6 network MTU (1280 bytes). This is the default behavior.

This setting does not affect packets that arrive at TAYGA already fragmented, or packets that must be fragmented to fit within the IPv6 network MTU.

See Also

tayga(8)
<http://www.litech.org/tayga/>