mtu1280d - emulates serving via a low MTU IPv6 tunnel ---------------------------------------------------- This program is will generate ICMPv6 "Packet Too Big" responses with an MTU of 1280. mtu1280d will connect to a netfilter_queue socket, listening for packets; and respond to all packets sent to that queue. This is meant to be ran on a secondary IP for your host. It is recommend that your primary IP is NOT used with this technique in case of application failure. To deploy, compile build and install. Copy in one of the init or init.d scripts, and make sure it is set for auto-start for your OS. An actual reboot is recommended. Once up and running, configure ip6tables to route large packets destined to the desired IP to the netfilter queue. Example rule: ``` guest% sudo ip6tables-save | grep NFQ -A INPUT -d 2001:470:1f04:d63::2/128 -m length --length 1281:65535 -j -NFQUEUE --queue-num 1280 ``` REQUIREMENTS ------------ RedHat/Centos/Fedora: * libnetfilter_queue-devel * gcc, make * ip6tables - and a way to automatically load ip6tables on startup Ubuntu/Debian: * build-essential * libnetfilter-queue-dev * ip6tables - and a way to automatically load ip6tables on startup IPTABLES / IP6TABLES -------------------- For reference, this is what jfesler does: /etc/rc.local: ``` iptables-restore /etc/iptables/rules.v4 ip6tables-restore /etc/iptables/rules.v6 ``` /etc/iptables/rules.v6 (simplified version, only includes mtu1280d rule) ``` # Generated by ip6tables-save v1.4.21 on Tue Feb 17 10:54:23 2015 *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -d 2001:470:1f04:d63::2/128 -m length --length 1281:65535 -j NFQUEUE --queue-num 1280 COMMIT ``` LICENSE ------- GPLv2, due to the duplicated code from Hararld Welte's libnetfilter_queue-1.0.2/utils/nfqnl_test.c (included).