I have an Aurora database on a VPC. Today I needed to connect to that database through Lambda. Not really an issue except I needed internet access in that Lambda and so I had to setup the following:
I added a new subnet for the public NAT.
I added a NAT Gateway and assigned it to a new EIP and the new subnet.
I added a new route table that routed all traffic to the igw and associated that table with the new subnet I created in step 1.
I modified the Main route table and routed all traffic to the NAT.
This gave me internet access in my Lambda, and by running the Lambda on the VPC, I also had access to my Aurora database.
However, I have now lost public access to this database through MySQL Workbench.
What do I need to configure to route the public traffic back to the VPC?
The fact that you could previously connect to the Amazon Aurora data base from your laptop suggests that Aurora was running in a Public Subnet. That is, a subnet that has a Route Table that sends Internet-bound traffic directly to the Internet Gateway.
You mention that you modified the Main routing table. It is likely that this routing table is associated with your Public Subnet (where Aurora is located), and that it was previously configured to send traffic to the Internet Gateway. However, it was probably modified to send traffic to the NAT Gateway. Therefore, the subnet was effectively changed into a Private Subnet (with no Route Table entry that points to the Internet Gateway).
If you really do want your database in the public subnet, then the configuration would be:
One public subnet, which contains the Aurora database and to which the Lambda function connects
A Route Table associated with the subnet that routes Internet-bound traffic (0.0.0.0/0) to the Internet Gateway
Possibly an additional subnet to provide High Availability for both Aurora and Lambda
No private subnet is required since you want Aurora in a public subnet.
A more secure option would be:
A public subnet with a jump box EC2 instance and the Lambda connection
A private subnet with Aurora
To connect to Aurora from your laptop, you would SSH into the Jump Box and use port forwarding to access the Aurora database. This way, the database is not exposed to the Internet.
The public subnet would have a different route table than the private subnet (thus making them private/public).
Related
I have created a VPC and internet gate way. And attached internet gateway to the vpc. Create two subnets one is public subnet and another is private subnet. And created a route table to route the traffic. In route table added a route rule 0.0.0.0/0 to IGW(internet gatway). To test this I launch a EC2 instance in public subnet. I have generated a public IP address example : (554.6.8.24). Using that IP address do ssh and I am connecting from local machine to EC2 instance.
My question is I am connecting to the EC2 instance from my local machine using public IP. What is the point of adding route rule in 0.0.0.0/0 to IGW(internet gatway) in route table?. With out route rule can I connect to Ec2?
If an Internet Gateway is not present in an Amazon VPC, then that VPC has no connection to the Internet. This can be very useful for creating private networks.
If you want to connect a VPC to the Internet, then you need to:
Create an Internet Gateway for that VPC
Create a Route Table that sends traffic to the Internet Gateway
Attach the Route Table to a Subnet (thereby making that subnet a Public Subnet since it routes to the Internet Gateway)
Put resources inside the Public Subnet (eg EC2 instances)
In contrast, Private subnets do not have a Route Table entry that points to an Internet Gateway. Therefore, those subnets cannot access the Internet. This is an added layer of security to prevent access to private resources.
The only difference between a Public Subnet and a Private Subnet is having the Route Table entry that points to an Internet Gateway. Without that entry, a subnet will remain private.
Any help would be much appreciated!
Initially we had 3 subnets in our AWS VPC. The VPC has an IGW and one default route table with 2 routes - 1 for internal and 0.0.0.0/0 to IGW. A standard initial VPC setup.
Within the VPC we have an RDS instance, with an RDS proxy, and the DB is set for public access while we develop the solution. The DB is associated with the default VPC SG along with a specific SG that whitelists IP addresses for DB connectivity via the public endpoint.
Also within the VPC we have a Lambda that is using the default VPC security group and the 3 subnets mentioned above.
The Lambda can connect to the RDS proxy, and we can connect to the RDS public endpoint via a whitelisted IP - This is as expected.
The Issue:
Now we need to provide the Lambda with internet access (it needs to connect with RedisLabs). To do this we've added:
A public subnet (subnet-00245f33edbae3358)
A NAT on the public subnet
Created a route table associated with the existing 3 private subnets (subnet-06d1124e, subnet-ba82bce1, subnet-3344b955) with a route of 0.0.0.0/0 -> NAT
Created a route table associated with the new public subnet (subnet-00245f33edbae3358) with a route of 0.0.0.0/0 -> IGW
With this is place the Lambda can still access the DB via the RDS proxy (expected) and can now access the internet (expected), BUT we lose connection to the DB via the public facing endpoint.
Is there something missing in the configuration that will allow Lambda access to the RDS and internet AND will also allow us access to RDS via the public endpoint? OR do we need an SSH tunnel within the public subnet to do this?
Thanks in advance!
Additional Info:
The RDS currently has the following SG's:
- prod-auth-service-rds - allows TCP 3306 from my whitelisted IP
- sg-11cb746b (default) - All traffic with, self referencing source (sg-11cb746b)
The RDS is on subnets:
- subnet-06d1124e - existing private subnet
- subnet-ba82bce1 - existing private subnet
- subnet-3344b955 - existing private subnet
The NAT is on subnet subnet-00245f33edbae3358
EDIT: Reread your response, if your RDS DB is on private subnets, then it can’t be publicly accessible regardless of of what you set as that option in the DB’s settings.
——-
After looking at the additional info, I believe the problem is your security group for the RDS. It only allows traffic from things in your default security group or your personal whitelisted IP.
Even though the lambda is in your default security group, RDS does see traffic as coming from your Lambda, they see it as coming from the NAT Gataway which doesn’t have and security groups.
You can solve this by adding the EIP of your NAT Gateway as an additional whitelisted IP to your inbound rules of the RDS SG.
It turns out that all I needed to do was create the Lambda in a private subnet(s) separate to the existing RDS subnets. The separate subnet(s) then need a route that forwards 0.0.0.0/0 to NAT.
The Lambda now has outbout internet access and RDS access, while the RDS instance can still be reached via its existing public endpoint.
The link explains that need to use NAT Gateway for the public subnet to make it possible to access the internet and the lambda function access the RDS instance. First does it realy have to be NAT Gateway can't use instead a Internet Gateway for that purpose?
Second have two Route Tables one named PublicNetwork that haves two subnets and the route haves one Internet Gateway,
the second Route Table that haves only one subnet called PrivateNetwork.
when had only one Route Table with all 3 subnets could access the rds (db) instance with Microsoft SQL Server Management (security group with inbound rules of type MS SQL and Source my ip address) now with the changes can't access anymore.
My database in RDS haves in Subnet group my default-vpc that haves the 3 subnets is it needed to create another vpc and transfer the private subnet to it to be able to access my database again?
All subnets in a VPC can communicate with each other
An Internet Gateway connects the VPC to the Internet
Any subnet that has a Route Table pointing 0.0.0.0/0 to the Internet Gateway is called a Public Subnet (because it can directly communicate with the Internet)
Any subnet that does not have such a Route table entry is called a Private Subnet
If a resource in a private subnet needs to communicate with the Internet, it must send the network traffic via a NAT Gateway in the Public Subnet. The NAT Gateway will forward the traffic to the Internet, then return any response that is received.
If you are having difficulty connecting to resources within the same VPC, then the Security Group is the most likely cause of the problem.
NETWORK:
I have a private subnet and a public subnet. A VPC with IG attached. There is a NAT Gateway in the public subnet. I also have 2 route table, the public route table routes everything to the IG, the private route table routes everything to the NAT Gateway.
EC2:
My EC2 Windows instance is in the private subnet with a EIP and a Public DNS. It has a security group that allows all fron internet inbound/outbound but i cant even ping neither rdp
All the machine or instances in the private subnet cannot be connected externally hence the name private subnet. If you want to connect to your instance externally you must place it in the public subnet (the subnet that is connected to the internet gateway). Eventhough, you attach an elastic ip (which is a public ip) but it is routed through a NAT. The EIP must go through the internet gateway only.
If you really want to connect you need to VPN to your VPC (using AWS VPC VPN) and then RDP to your instance. Or have a gate instance in your public subnet.
Verify that the route table for the subnet has a route that sends all traffic destined outside the VPC to the internet gateway for the VPC. For more information, see Creating a Custom Route Table (Internet Gateways) in the Amazon VPC User Guide.
I am trying to setup a nice and secure VPC for my lambda and RDS work. Essentially, I want my lambda to hit a site, get some data, and shove it into a database.
In isolation the parts all work. However the second I go to harden everything it all falls apart. Here is what I do:
Disable "Publically Available" from the RDS instance
Change the RDS instance to only accept connections from inside the VPC using the security group
Associate the lambda with a VPC (this kills the internet access)
Following this tutorial I created a NAT gateway, deleted the internet gateway from the VPC subnet, and replaced it with the NAT. Now, as expected, nothing can talk inbound, but things can talk outbound.
At this point I knew I needed a bastion instance, so I fired up an EC2 instance.
The EC2 instance is set to the same subnet the RDS and Lambda are on, and unfortunately this means that I have a problem - the NAT gateway is currently soaking up all the traffic via 0.0.0.0/0, which means there's no room for the internet gateway. Without the internet gateway I (obviously) can't SSH into my bastion instance so I can jump to access my RDS database.
How can I configure this all correctly? My guess is that I need to split the subnet up somehow and make a private and public subnet, the public having the bastion and internet gateway in it. However, I'm not sure how this will all work so the bastion instance can still properly jump to the RDS.
I'm really quite new to setting up AWS services so I'm hoping I didn't mess anything up long the way.
Following this tutorial I created a NAT gateway, deleted the internet
gateway from the VPC subnet, and replaced it with the NAT. Now, as
expected, nothing can talk inbound, but things can talk outbound.
Short Answer
The short answer is you shouldn't have "Killed the Internet Gateway"; thats not a step in the link you provided :) Leave the internet gateway as is in your current subnet. You're going to need a public subnet and the one that was routing 0.0.0.0/0 to IGW is an example of one you can could use.
The work involved is placing your NAT gateway in the Public Subnet, placing your bastion host in the public subnet, placing your lambda function in the private subnet, routing traffic in the private subnet to the NAT gateway in the public subnet, and providing your lambda function with access to your security group by putting it in its own lambda security group and "white listing" the lambda security group in the inbound rules for the security group protecting your database.
Background
Below I have an expanded answer providing background as to public/private subnets, granting internet access to private subnets, and allowing lambda access through security groups. If you don't feel like reading the background then jump to very end where I give a bullet point summary of the steps you'll need.
Public Subnet
A public subnet is one in which traffic originating outside your VPC, or destined for a target outside your VPC (internet), is routed through an internet gateway (IGW). AWS gives you initial default public subnets configured this way; you can identify them in the console by looking at their route table and seeing that under "destination" you find "0.0.0.0/0" targeting an IGW. This means a public subnet is more of a design pattern for "internet accessible" subnet made possible by simply configuring its default route to point to an IGW. If you wish to create a new public subnet you can create a new route table as well that point internet traffic at an IGW and link that route table to your new subnet. This is fairly easy in the console.
Private Subnet
A private subnet is a subnet with no IGW and not directly reachable from the internet, meaning you cannot connect to a public IP address of a system on a private subnet. With the exception of the AWS pre-configured default subnets, this is how new subnets your manually create are setup, as black boxes till you specify otherwise.
Granting Internet Access to Private Subnet
When you want things in your private subnet to be able to reach out to external internet services you can do this by using an intermediary known as a NAT gateway. Configure a route table the same as in the public subnet with the only difference being traffic destined for 0.0.0.0/0(Internet) you target for a NAT gateway sitting inside the public subnet. That last part is critical. Your NAT gateway needs to be in the public subnet but your private subnet is using it as the target for external traffic.
Security Group Access for Lambda
One simple way to allow your lambda function through your security group/firewall is to create a security group just for your lambda function and configure the security group protecting your RDS so that it allows traffic from the lambda security group.
In other words, in security group settings you don't have to specify just IP addresses as sources, you can specify other security groups and this is a pretty neat way of grouping items without having to know their IP address. Your lambda functions can run in the "Lambda Security Group" and anything protected by a security group that you want them to access can be configured to accept traffic from the "Lambda Security Group". Just make sure you actually associate your lambda function with the lambda security group as well as place it in the private subnet.
Lambda VPC Steps in a Nutshetll
Create a new NAT gateway and place it in the public subnet. This
point is important, the NAT gateway goes in the public subnet ( a
subnet whose route table routes 0.0.0.0/0 to an IGW)
Create a new subnet, you can call it Private-Lambda-Subnet. Unlike
the
default pre-configured subnets AWS gives you, this new subnet is
immediately private out of the box.
Create a new route table and link it to your Private-Lambda-Subnet
In the new route table for your private subnet add an entry that
routes 0.0.0.0/0 to a target of the NAT gateway. This is how your
private subnet will indirectly access the internet, by forwarding
traffic to the NAT which will then forward it to the IGW.
Your bastion host and anything else you want to be be publicly
accessible will need to be in the public subnet. This is probably
where you already have your RDS instances, which is fine if they are
firewalled/security group protected.
Create a new security group for your lambda function(s). You can
call it LambdaSecurityGroup.
Configure the inbound rules of your RDS guarding security group to
allow traffic from the LambdaSecurityGroup. This is possible because
you can use other security groups as sources in the firewall
settings, not just ip addresses.
You need a public subnet (default route is the Internet Gateway) and a private subnet (default route is the NAT Gateway). The NAT Gateway, itself, goes on the public subnet, so that it can access the Internet on behalf of the other subnets for which it is providing services. The bastion also goes on the public subnet, but Lambda and RDS go on the private subnet.
Anything can talk to anything on any subnet within a VPC as long as security groups allow it (and Network ACLs, but don't change these unless you have a specific reason to -- if you aren't sure, then the default settings are sufficient).