IT notes

Centos Disable Ipv6

Edit file /etc/default/grub and add ipv6.disable=1, example: # cat /etc/default/grub GRUB_TIMEOUT=5 GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="ipv6.disable=1 crashkernel=auto rhgb quiet" GRUB_DISABLE_RECOVERY="true" Then regenerate and reboot: grub2-mkconfig -o /boot/grub2/grub.cfg And reboot Using sysctl (no need to reboot), append below lines in /etc/sysctl.conf: net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 Then run: sysctl -p IPv6

Configure IPv6 using dhcp6c for servers from pkg install dhcp6 Transform the DUID into a binary file (needed for dhcp6c): echo <DUID> | awk '{ gsub(":"," "); printf "0: 0a 00 %s\n", $0 }' | xxd -r > /var/db/dhcp6c_duid Add this in /usr/local/etc/dhcp6c.conf: id-assoc pd { prefix-interface igb0 { }; }; id-assoc na { }; interface igb0 { send ia-pd 0; send ia-na 0; }; Add this to /etc/rc.


VPS providers that allow use your own image/kernel Google cloud (only ipv4) Allows to upload compreses raw images: tar --format=gnutar -Szcf disk.tar.gz disk.raw MTU needs to be set to 1460 and in some cases disable the checksum offload Amazon AWS (only ipv4) Images can’t be uploaded compressed, ans disabling TSO is required: ifconfig_DEFAULT="SYNCDHCP -tso" IPV6 support vultr Instead of uploading the raw images, they will be fetched, a URL needs to be provider from where the image can be downloaded.

ipv6 off

Turn off IPv6 on mac First list interfaces: $ networksetup -listallnetworkservices An asterisk (*) denotes that a network service is disabled. Thunderbolt Ethernet Wi-Fi Bluetooth PAN Thunderbolt Bridge Next: $ networksetup -setv6off "Thunderbolt Ethernet" For Wi-Fi: $ networksetup -setv6off Wi-Fi

ipv6 tunnelbroker

6in4 6in4 uses tunneling to encapsulate IPv6 traffic over explicitly-configured IPv4 links. The 6in4 traffic is sent over the IPv4 Internet inside IPv4 packets whose IP headers have the IP protocol number set to 41. “6to4” is a tunneling method that is only interesting for reaching IPv6-only services. And 6to4 makes sense only if one has a public IPv4 address. As a rule, you only need to enable “6to4” if you want to access services that are only IPv6.