[CentOS] IPv6 range provisioning question

Vadtec vadtec at vadtec.net
Wed Jun 10 23:58:55 UTC 2009


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Louis Lagendijk wrote:
> On Wed, 2009-06-10 at 13:08 -0500, Vadtec wrote:
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>> A few months back, I tried to use the network scripts to provision an IPv6 range
>> like can be done with IPv4. I was using CentOS 5.2 at the time and was informed
>> that 5.2 was broken in this regard. I have upgraded to CentOS 5.3 now and I am
>> trying to get IPv6 to provision an entire range of IPs, but I am still getting
>> the old behavior and no IPs are being provisioned.
>>
>> I have been following the docs provided by the link in the
>> /etc/sysconfig/network-scripts/ifup-ipv6 at
>> http://www.deepspace6.net/projects/initscripts-ipv6.html#id2801589 and using the
>> following configs:
>>
>> /etc/sysconfig/network
>> NETWORKING=yes
>> GATEWAY=***.***.***.***
>> GATEWAYDEV=eth0
>> HOSTNAME=vadtec
>>
>> NETWORKING_IPV6=yes
>> IPV6FORWARDING=no
>> IPV6_AUTOCONF=no
>> IPV6_AUTOTUNNEL=no
>> IPV6_DEFAULTDEV=eth0:1
>> IPV6_DEFAULTGW=2001:0470:0103:001A::1
>>
>> /etc/sysconfig/network-scripts/ifcfg-eth0-1
> Why do you need an alias device here? Put the ipv6 config on the eth0
> device,and add the configuration to the ifcfg-eth0 file
> 
>> DEVICE=eth0:1
>> IPV6INIT=yes
>> IPV6ADDR=2001:0470:0103:001A:0001:0000:0000:0000:/96
> You are allocating a /96 with all 0 in the last 32 bits. So you are not
> allocating an address. Why a /96? Using a /64 is pretty much the
> standard for ipv6. 
> 
>> IPV6_AUTOCONF=no
>> IPV6_ROUTER=no
>> IPV6FORWARDING=no
>> ONBOOT=no
>>
>> When I run service network restart, it doesn't even provision the default IPv6
>> GW on eth0:1, nor does eth0:1 even show up.
> I must admit I never tried an v6 address on an alias, so I have no clue
> whether it works or not. But you can have both v4 and v6 addresses next
> to each other on the eth0 device
>> If I run tail /var/log/boot.log, boot.log is empty. If I run tail
>> /var/log/messages, I see varying amounts of:
>>
>> Jun 10 11:42:14 localhost kernel: [208192.884652] eth0: duplicate address detected!
>>
> Probably due to the all 0 in the part AFTER the /96
>> I see no other errors or messages saying anything is wrong or otherwise.
> Autoconfiguration is the way to go if you want to make it easy. On my
> server I set the addresses manually like
> DEVICE=eth0.159
> ONBOOT=yes
> BOOTPROTO=none
> NETMASK=255.255.255.0
> HWADDR=00:1a:92:d6:99:91
> IPADDR=192.168.159.1
> #GATEWAY=192.168.178.1
> TYPE=Ethernet
> USERCTL=no
> IPV6INIT=yes
> IPV6FORWARDING="yes"
> # v6 address changed to protect the innocent
> IPV6ADDR="2001:888:118e:18a2::1/64"
> PEERDNS=no
> VLAN=yes
> Please not that I am using vlans, hence the .159 on the eth0. Normally
> you do not need that and you leave the VLAN=yes off.
> Please note the ::1 at the end of the address.
> I use radvd on that machine (so here I need to set fixed v6 addresses),
> but the clients do not neede that:
> 
> DEVICE=eth0
> BOOTPROTO=none
> DNS1=192.168.159.1
> IPADDR=192.168.159.3
> NETMASK=255.255.255.0
> HWADDR=00:11:d8:be:98:fa
> ONBOOT=yes
> SEARCH="pheasant"
> USERCTL=no
> PEERDNS=no
> IPV6INIT=yes
> NM_CONTROLLED=yes
> GATEWAY=192.168.159.1
> TYPE=Ethernet
> 
> Here the address is set depending on the (/64) prefix received from the
> radvd server.....
> 
> kind regards, Louis
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos

Thanks for the tip about having all zeros at the end of the IP. I figured the
script would go ahead and provision the IPs anyways. The reason I was using a
/96 is because the machine happens to be a VPS with only 128MB of RAM, so I
figured the less IPs I provision the less memory it will take up, which is
limitted anyways. I also do not want to use radvd or auto configuration because
I do not need to broadcast or forward ipv6 on this vps.

As per your suggestions, I removed the extra zeros and changed the prefix to /64.

I am now using the following configs:

/etc/sysconfig/network:
NETWORKING=yes
GATEWAY=67.202.107.1
GATEWAYDEV=eth0
HOSTNAME=vadtec

NETWORKING_IPV6=yes
IPV6FORWARDING=no
IPV6_AUTOCONF=no
IPV6_AUTOTUNNEL=no
IPV6_DEFAULTDEV=eth0
IPV6_DEFAULTGW="2001:0470:0103:001A::1"

/etc/sysconfig/network-scripts/ifcfg-eth0:
DEVICE=eth0
IPADDR=***.***.***.***
NETMASK=255.255.255.0
BROADCAST=***.***.***.***
ONBOOT=yes

IPV6INIT=yes
IPV6ADDR="2001:0470:0103:001A::2/64"
IPV6_AUTOCONF=no
IPV6_ROUTER=no
IPV6FORWARDING=no
PEERDNS=no
VLAN=no


However, this is not provisioning an entire range as follows:

eth0      Link encap:Ethernet  HWaddr 00:16:3E:70:FC:96
          inet addr:***.***.***.***  Bcast:***.***.***.***  Mask:255.255.255.0
          inet6 addr: 2001:470:103:1a::2/64 Scope:Global
          inet6 addr: fe80::216:3eff:fe70:fc96/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:70 errors:0 dropped:0 overruns:0 frame:0
          TX packets:29 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:6738 (6.5 KiB)  TX bytes:2050 (2.0 KiB)

I also have a large number of "unreachable" routes shown on the local loopback
when I do ip -6 route show:
unreachable ::/96 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
hoplimit 4294967295
unreachable ::ffff:0.0.0.0/96 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295
unreachable 2002:a00::/24 dev lo  metric 1024  error -101 mtu 16436 advmss 16376
hoplimit 4294967295
unreachable 2002:7f00::/24 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295
unreachable 2002:a9fe::/32 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295
unreachable 2002:ac10::/28 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295
unreachable 2002:c0a8::/32 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295
unreachable 2002:e000::/19 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295
unreachable 3ffe:ffff::/32 dev lo  metric 1024  error -101 mtu 16436 advmss
16376 hoplimit 4294967295

I assume those are something to do with how IPv6 works, but I'm not sure.

So, back to my original question, I have it provisioning *one* IP, how do I get
it to provision a *range* of IPs. As I said above, this is a VPS that does not
need to broadcast any of its IPs or forward IPv6. I just need to be able to
provision a range of IPv6.

Thanks for the help so far!

Vadtec
vadtec at vadtec.net
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