Note:
There is an existing stackoverflow post which discuss about --master-ipv4-cidr, but it doesn't discuss about the topic which I am asking in the question.
Please don't mark this as duplicate.
Problem description
I am creating private clusters in GKE and got confused with the --master-ipv4-cidr range. This link, mentions that --master-ipv4-cidr needed CIDR in RFC 1918 range.
"--master-ipv4-cidr 172.16.0.0/28 specifies an RFC 1918 range for the master. This setting is permanent for this cluster."
Since valid RFC 1918 ranges are
10.0.0.0 - 10.255.255.255 (10/8 prefix)
172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
192.168.0.0 - 192.168.255.255 (192.168/16 prefix)
So I tried to create private cluster with following values:
--master-ipv4-cidr "172.17.0.0/28"
--cluster-ipv4-cidr "172.16.128.0/17"
--services-ipv4-cidr "192.168.1.0/24"
Since 172.17.0.0/28 is also from RFC 1918 range I thought that cluster will come up. But it resulted in error as mentioned below
172.17.0.0/16 is a reserved GKE IP range and cannot be used for the 'master-ipv4-cidr'.
Then I changed --master-ipv4-cidr to example given in link and cluster created successfully. Below are the successful case values.
--master-ipv4-cidr "172.16.0.16/28"
--cluster-ipv4-cidr "172.16.128.0/17"
--services-ipv4-cidr "192.168.1.0/24"
Now my question are
Does --master-ipv4-cidr expects CIDR in 172.16.0.0/28 only and it cannot accept any other range from 10/8 or 192.168/16 or any other range for example 172.17.0.0/28 which I provided earlier?
With an existing cluster --master-ipv4-cidr of 172.16.0.0/28, if I create another cluster in same VPC what should be the --master-ipv4-cidr value?
Because creating another cluster with same --master-ipv4-cidr 172.16.0.0/28 fails with below error which is quite expected.
Google Compute Engine: An IP range in the peer network (172.16.0.16/28) overlaps with an IP range (172.16.0.16/28) in an active peer (gke-c2a126697c6fee94c2b8-1e18-f2ff-peer) of the local network.
and thats expected because 172.16.0.16/28 already exist in an existing cluster in same vpc to which its getting peered.
I am thinking to manage my cluster pods from 172.16.0.0 range and services from 192.168.0.0 range of RFC 1918 and not use 10/8 network to avoid conflict with existing office network.
Since 172.16/12 is a superset of 172.16.0.0/28. How do you make sure that they are separated from each other?
Apologies for asking many question here, but I am just trying to keep the entire context at same place.
I will answer your questions as follows:
172.17.0.0 cannot be used because this is for Docker.
You can use any of the following CIDRs 10.0.0.0 – 10.255.255.255, 172.16.0.0 – 172.31.255.255, 192.168.0.0 – 192.168.255.255 except 172.16 and 172.17. Also this must be /28
Supersets or Subnets are not possible therefore you will have to choose a different CIDR range
You can read about the Restrictions and Limitations in the following Google Public doc
Related
I need to add a route in GCP's VPC Network and when I do, I get an error (shown below) that appears to state there is an overlap/conflict with the 10.130.0.0/16 range. I unfortunately do not see this 10.130.0.0/16 in any route, in any region and I have no idea why this error is occurring.
Creating route "test" failed. Error: Invalid value for field 'resource.destRange': '10.130.90.82/32'. 10.130.90.82/32 hides the reserved address space for network (10.130.0.0/16).
I have tried adding this simple route in several gcp projects but they all fail and seem to imply there might be some hidden reserved address space. Could this be? What am I missing? This occurs with any route destination value that is in the 10.130.0.0/16 space eg; 10.130.90.82/32 10.130.90.0/24
For clarification here is an example Route that fails:
Additional Clarification, Here is the 'default' VPC Network:
Google Cloud does not allow you to create a new subnet or peering subnet route whose destination exactly matches or is broader than (would contain) an existing custom static route. For example, if your VPC network has a custom static route for the 10.70.1.128/25 destination, Google Cloud prohibits the creation of any subnet or peering subnet route with a primary or secondary subnet IP address range of 10.70.1.128/25, 10.70.1.0/24, or any other range that contains all the IP addresses in 10.70.1.128/25.
Kindly check Configuring private services access docs. Included on the docs are the considerations , Creating an IP allocation, Deleting an allocated IP address range etc.
There is in fact a hidden reserved address space in the default VPC network. I hesitate calling hidden as JaysonM mentioned it in his answer but it does not appear anywhere in the GPC console (to my knowledge).
The default VPC network is using 'auto' subnet creation mode. With this setting enabled the VPC network has a range of 10.128.0.0/9 (10.128.0.0 - 10.255.255.255) that cannot be overlapped. Simply setting 'auto' subnet creation of the VPC network to 'custom' will resolve this issue. Do also note this is a one-way change for your VPC network.
Cheers!
I haven't found anything that details out how to add a range through the AWS portal. I have a range of salesforce ids that I need to add. When i set the server to only allow from specific ids I'm unable to reach the server by adding the basic single addresses. I found an address in the first range which allowed traffic, but when I've restricted access to only the listed ips I'm unable to ping salesforce from the server. I have all outbound traffic allowed. Also, when I allow all traffic, I am able to ping in both directions. I have very limited network experience, so any help is appreciated. Here is an example of the first ARIN range 13.108.0.0 - 13.111.255.255
If you have a range like 13.108.0.0 - 13.111.255.255 first convert that to a CIDR range using a web site that can do the conversion: wmtips
Then add the CIDR address to the inbound rules of the security group attached to your EC2 (Make sure the correct protocol is selected). This is to allow access for the remote system. Set the outbound rules on the security group to 0.0.0.0/0.
So, I am working to migrate from EC2 Classic to VPC (yeah, I know, long time in coming and this was an inherited platform).
I have created a VPC and when I go to turn on Classic Link, I get the following error:
The CIDR range of vpc-[id_here] overlaps with the Classic IP space
I looked and was not able to find a way to determine which IP Range(s) Classic uses. Is there a way to find out so I can make my VPC's not stomp all over it?
Thanks!
10.0.0.0/8 as documented here.
As in the comment above:
"VPCs that are in the 10.0.0.0/16 and 10.1.0.0/16 IP address ranges can be enabled for ClassicLink
Originally asked on the AWS forums but I get the sense I won't hear back for quite some time, so I'm also posing my questions here:
I recently set up a Client VPN based on this guide. When connected I'm successfully able to access the internet as well as resources in a private subnet, so at this point I have a basic understanding of how all the parts fit together, except for one: the Client CIDR range. This concept gave me so much trouble that I think it stretched out the time-to-build by 2 days because of all the thrashing I did trying to connect it to the other concepts Client VPN involves. But it bugs me when I don't fully understand a thing so I have some questions about it:
Does the Range benefit at all from being in the same CIDR range as the VPC it's a part of, assuming it doesn't overlap with target network(s)? Why or why not?
Why does the Range need to be of size /22, while target networks can be as small as /27? Doesn't that imply 2^5 more clients could be attempting to access a resource in a VPC as there are available addresses in a given subnet?
In setting up security groups for the private subnet I noticed that I had to use rules based on the CIDR range of the target subnet client connections landed in, rather than the Client CIDR range - why is that?
As you can probably tell from my questions, I'm not a network administrator. I'm trying to understand that world at the same time I'm trying to spin up useful infrastructure. My guess is the answers to these questions are blindingly obvious to someone with experience in that area, but I just don't get it.
Here are my attempts at clarification:
So the range shouldn't overlap the VPC CIDR supernet (and individual subnets within the VPC) or you may get routing conflicts. So I'm not sure what you are referring to? Can you provide your configuration.
From what I can tell the /16 to /22 range is just something that is not technical restriction, probably because AWS hadn't had a chance to add a feature that would allow this to have more options. I'm assuming you want a smaller range? In Azure P2S VPN, there is not such restriction - their minimum pool is a /29.
SGs are applied to resources such as EC2s and not VPCs directly but in the inbound rules you can specific CIDRs directly - so I'm not sure what you are referring to... do you have the specific example you could share?
I have a problem with determining the correct number of available IP addresses per private IP address range for an AWS VPC for example.
Given that AWS allows assigning a range starting from a /16 block, I have the following available ranges. Given the fact they take 4 addresses away from me, this leaves me with the following ranges:
10.0.0.4 - 10.0.255.254
172.16.0.4 - 172.16.255.254
192.168.0.4 - 192.168.255.254
According to all calculators available on the internet, I get the same amount of IP addresses (65331). Nevertheless I've seen numerous recommendations to choose 10.0.0.0 as the address range, as it provides the highest number of IP addresses. Can somebody clarify this?
Thank you very much
not sure if I understand your question too well, but I will try to shed some light on what you are asking. AWS uses those 4 IPS for their internal routing and configuration of their network.
Example VPC Address Range: 10.0.0.0/16
If you have this CIDR example, AWS takes the first 4 for their own resources of each SUBNET and you have access to the rest of these IPS in the given SUBNETS.
Now we can break that VPC down into smaller subnets so it can be used for different reasons such as the standard ( Pub / Private ).
Example Subnet : 10.0.0.0/27 = 32 IPS
32 - 4 = 28
AWS Also does not support .255(network broadcast address) of a subnet, so they take the last IP as well which gives you a total for 28 - 1 = 27 IPS for use.
Sources: https://docs.aws.amazon.com/vpc/latest/userguide/VPC_Subnets.html