IPV6 network boot with iPXE

IPv6地址获取方式

IPv6地址获取主要分为以下几种

IPv6地址获取方式

	预设闸道	地址分配	DNS
手动配置	手动	手动	手动
SLAAC RDNSS	RA	RA	RA
SLAAC DHCPv6	RA	RA	DHCP
Stateful DHCPv6	RA	DHCP	DHCP

RA: Router Advertisement

SLAAC: Stateless Address Autoconfiguration

RDNSS: Recursive DNS Server

自动获取IPv6地址时获取信息的方式主要通过RA的M位与O位控制.

• M (Managed Address Configuration)
• O (Other Configuration)

M = 1 表示 Client需要去DHCPv6获取 IPv6 Prefix

O =1 表示 Client需要去DHCPv6获取DNS等信息

1. SLAAC + RDNSS M = 0, O = 0 Client将从RA获得prefix, DNS等信息. RA一般由Router提供, 在Linux环境下可以通过radvd服务提供
2. SLAAC + DHCPv6 M = 0, O = 1 Client将从RA获取prefix, 其他信息比如DNS由DHCPv6提供
3. Stateful DHCPv6 M = 1, O = 1 Client将从DHCPv6获取所有信息

IPv6地址获取流程

Client 使用UDP 546 端口, Server 使用 UDP 547 端口, 但IPv6不使用 broadcast方式获取地址.

假设

Server的 link-local address 是 fe80::6e92:bfff:fe07:bbb9

Client的 link-local address 是 fe80::21b:21ff:fe36:607e

IPv6 multicast addresses ff01::1:2

• DHCPv6 client sends a Solicit from [fe80::6e92:bfff:fe07:bbb9]:546 for [ff01::1:2]:547
• DHCPv6 server replies with an Advertise from [fe80::21b:21ff:fe36:607e]:547 for [fe80::6e92:bfff:fe07:bbb9]:546
• DHCPv6 client replies with a Request from [fe80::6e92:bfff:fe07:bbb9]:546 for [ff01::1:2]:547
• DHCPv6 server finishes with an Reply from [fe80::21b:21ff:fe36:607e]:547 for [fe80::6e92:bfff:fe07:bbb9]:546

RADVD

Managed will tell the target host to request its IPv6 address from a DHCPv6 server instead of using SLAAC.

Other is important bit, as it tells the target host that (non-address related) configuration information is available from the DHCPv6 server.

/etc/dhcp/radvd.conf

interface eth0
{
        AdvSendAdvert on;
        MinRtrAdvInterval 30;
        MaxRtrAdvInterval 100;
        AdvManagedFlag on;
        AdvOtherConfigFlag on;
        prefix 3ffe:501:ffff:100::/64
        {
                AdvOnLink on;
                AdvAutonomous on;
                AdvRouterAddr off;
        };

};

启用radvd时必须启用 IPv6 forwarding功能

 echo "net.ipv6.conf.all.forwarding = 1" >> /etc/sysctl.conf | sysctl -p

DHCPv6 (isc-dhcp-server)

/etc/dhcp/dhcpd6.conf

default-lease-time 2592000;
preferred-lifetime 604800;
option dhcp-renewal-time 3600;
option dhcp-rebinding-time 7200;
allow leasequery;
option dhcp6.preference 255;
option dhcp6.info-refresh-time 21600;
dhcpv6-lease-file-name "/var/lib/dhcpd/dhcpd6.leases";

option dhcp6.name-servers 2001:4860:4860::8888;  # Use Google's Public DNS Server
option dhcp6.domain-search "test.example.com","example.com";
option dhcp6.user-class code 15 = string;
option dhcp6.vendor-class-data code 16 = string;
option dhcp6.bootfile-url code 59 = string;
option dhcp6.client-arch-type code 61 = array of unsigned integer 16;

if exists dhcp6.user-class and
        substring(option dhcp6.user-class, 2, 4) = "iPXE" {
        option dhcp6.bootfile-url "http://[3ffe:501:ffff:100::1]/start.ipxe";
} else {
        if option dhcp6.client-arch-type = 00:00 {
         option dhcp6.bootfile-url "tftp://[3ffe:501:ffff:100::1]/undionly.kpxe"; # Standard PC BIOS
        } elsif option dhcp6.client-arch-type = 00:06 {
         option dhcp6.bootfile-url "tftp://[3ffe:501:ffff:100::1]/ipxe.efi"; # 32-bit x86 EFI
        } elsif option dhcp6.client-arch-type = 00:07 {
         option dhcp6.bootfile-url "tftp://[3ffe:501:ffff:100::1]/ipxe.efi"; # 64-bit x86 EFI
        } elsif option dhcp6.client-arch-type = 00:09 {
         option dhcp6.bootfile-url "tftp://[3ffe:501:ffff:100::1]/ipxe.efi"; # 64-bit x86 EFI(obsolete)
        } elsif option dhcp6.client-arch-type = 00:0a {
         option dhcp6.bootfile-url "tftp://[3ffe:501:ffff:100::1]/ipxe.efi"; # 32-bit ARM EFI
        } elsif option dhcp6.client-arch-type = 00:0b {
         option dhcp6.bootfile-url "tftp://[3ffe:501:ffff:100::1]/arm64.efi"; # 64-bit ARM EFI
        } 
}

subnet6 3ffe:501:ffff:100::/64 {
        range6 3ffe:501:ffff:100::10 3ffe:501:ffff:100::50;
        range6 3ffe:501:ffff:100:: temporary;
        prefix6 3ffe:501:ffff:100:: 3ffe:501:ffff:111:: /64;
}

tftp server

/etc/xinetd.d/tftp

flags默认是IPv4 仅支持IPv4; 修改为IPv6后同时支持IPv6和IPv4

service tftp
{
        socket_type             = dgram
        protocol                = udp
        wait                    = yes
        user                    = root
        server                  = /usr/sbin/in.tftpd
        server_args             = -s /var/lib/tftpboot
        disable                 = no
        per_source              = 11
        cps                     = 100 2
        flags                   = IPv6
}

http server

Just deploy a simple http server to serve http request.

iPXE

start.ipxe

#!ipxe
set conn_type http
chain --autofree http://[3ffe:501:ffff:100::1]/menu.ipxe || echo HTTP failed, localbooting...

menu.ipxe

#!ipxe
show ip6
set menu-timeout 5000
set submenu-timeout ${menu-timeout}

# Ensure we have menu-default set to something
isset ${menu-default} || set menu-default localhdd

set boot-url http://[3ffe:501:ffff:100::1]
set keep-san 1

######## MAIN MENU #############
:start
menu iPXE Boot Menu
item
item --gap --      -------Advanced configuration -----------
item --key 0 localhdd   [0] Local HDD
item --key 2 linux      [2] Linux Install
item --gap --            ---------------------------

choose --default  ${menu-default} --timeout 30000 target && goto ${target}

##### Main Items ########
:localhdd
exit

:linux
menu Linux Menu
item redhat74   RedHat74

choose target && goto ${target}

:redhat74
echo Install Red Hat 7.4
set centos_url ${boot-url}/linux/redhat/7.4
iseq ${platform} efi && goto centos_efi || goto centos_legacy
        :centos_efi
        echo Starting Install RedHat (UEFI)
        kernel ${centos_url}/images/pxeboot/vmlinuz initrd=initrd.img inst.loglevel=debug repo=${centos_url} noipv4 ip=dhcp6
        initrd ${centos_url}/images/pxeboot/initrd.img
        boot
        :centos_legacy
        echo Starting Install CentOS (Legacy BIOS)
        kernel ${centos_url}/images/pxeboot/vmlinuz  initrd=initrd.img repo=${centos_url}
        initrd ${centos_url}/images/pxeboot/initrd.img
        boot