I need to set up a custom DNS server within EC2. I have one instance that acts as the DNS server, and N other instances that use this DNS server to connect to one another. Is this posible? Basically, I need to modify the DHCP settings for the N instances so that they connect to the DNS server. I can't find any good documentation on modifying the DHCP settings for an instance.
Note: I did find some documents, but they seem to only apply to Amazon VPC. Is there any way to do this without using VPC?
Short answer - no. You need a VPC. But once you have the VPC created - you can effectively do whatever you like with it.
Long answer - traditional AWS hosting gets an address directly from Amazon. This means you've got no control whatsoever of the IP addresses.
New accounts however come with a VPC by default, which means you can install a machine to act as a DNS server. (And I've done this in the past using Windows Active Directory)
Related
I am doing a lift and shift with software from an on-premises architecture. There are two servers (main and auxiliary) that have to talk to one another over the network. I currently have tested and confirmed that I can manually add their hostnames and private IP address to the hosts file ("C:\Windows\System32\drivers\etc\hosts") and the software works fine.
For those that don't know, this file is used by Windows to map a network hostname like EC2AM-1A2B3C to a IP address. So if I added the hostname and IP address of the main server into the hosts file of the auxiliary server, then the auxiliary server could route to the main server. (i.e. PS> ping EC2AM-1A2B3C would then work).
How could I pass the required information to both servers? They both have to know the other server's private IP address and hostname. If this is not possible at server spin-up time, how might the servers connect and pass this information? I would really like to automate this if possible.
According to your description, I have some suggestions that you can refer to.
If you want two EC2 instances to be able to communicate with each
other, you can use the method of adding rules to the security group.
(1) Create security groups for your instance 1 and instance 2 respectively.
(2) Add an inbound rule to the security group of instance 1, chose "ICMP-ipv4". Enter the security group ID of instance 2.
(3) Create the inbound rule for instance 2 in the same steps.
For more information on security group rules you can refer to the official document.
You have tried adding the hostname and IP address of the primary
server to the host file of the secondary server. To tell each other
the IP Address of the other machine. Amazon CloudFormation cannot
handle the circular dependency between the two instances.
You can refer to the answer of this question. To realize that both instances know each other's IP address.
Hope these suggestions are useful to you.
I have an ec2 box, it is an ubuntu 18.04 OS. I can using "ssh -i {pemfile} ubuntu#{ip address}" also "ssh -i {pemfile} ubuntu#{ip-ipaddress.us-east-2.compute.internal}" from another EC2 box. Now I wanted to change the hostname and use it in ssh. I followed some of linux and AWS articles AWS Article and changed /etc/hostname and /etc/hosts file. Can not use route 53 DNS entry as per requirement.
/etc/hosts = 10.0.1.190 dev-host.example.trade
/etc/hostname = dev-host.example.trade
Getting below error "ssh -i {pemfile} ubuntu#dev-host.example.trade"
ssh: Could not resolve hostname dev-host.example.trade: Name or service not known.
As you’ve made the changes on the server only these will only be resolvable on that host (otherwise anyone could use any domain).
There are a few options you can take if you want to use a custom domain name.
The obvious one is you can use a domain you control, this will allow it to resolve across any hosts that are able to resolve your public DNS. If you don’t own a domain you can purchase one through a registrar (such as Route 53).
The second option is to look at using Route 53 private hosted zones. By attaching to your VPC you can set DNS records that resolve within your VPC. If you want these records to resolve in a hybrid network you would need to look at adding a DNS resolver.
The third option is to look at using a resource that can resolve the domain name, to do this you would either join a domain (using a service such as managed active directory or simple directory), or you could setup an EC2 host to resolve DNS. This is an expensive solution and the most complex if you’re using a hybrid architecture.
Take a look at the Centralized DNS management of hybrid cloud with Amazon Route 53 and AWS Transit Gateway post for more information about hybrid DNS
Your local machine knows nothing about changes you've made to the EC2 configuration. Those changes are local to the EC2 instance.
One way to connect to your cloud instance via a DNS name like dev-host.example.trade is to associate an elastic IP to the EC2 instance. Elastic IPs persist even if the instance is rebooted.
Next, create a new A-type DNS record at your DNS provider pointing to the newly issued IP address.
You can now connect to the server with the DNS name.
I would like set DNS records visible from instances inside the Google cloud.
For example if I query DNS from my PC I'll get one IP; however if I query DNS from the instance I'll get another IP. (A record to be exact)
Ideally I'd like doing this in most sane/convenient way possible; since I can install caching DNS server on every instance and setup authorative results; and forward caching for the rest (I guess bind9 can do that, never tried it before). But this is configuration sync mess; and it's not elegant. I kinda assume there might exist a better way.
One solution is to use totally different zones for different sets of machines and use the DNS search path to select.
So for example you could set up
server1.internal.yourdomain.com IN A 1.2.3.4
server1.external.yourdomain.com IN A 5.6.7.8
Then set up your machines with resolv.conf containing either
search internal.yourdomain.com
or
search external.yourdomain.com
And then when you lookup server1 on such a machine it will return the address from the appropriate zone. This scheme means you don't need to rely complex routing or IP detection. You will be immune to incidents where internal or external IPs get leaked into each others result.
Of course this does mean that you aren't keeping any IP addresses secret, so make sure you have other security layers in place (you probably shouldn't rely on secret IPs for security anyway)
Assuming you want your VM instances to be able to query other instances by name, and retrieve the desired instance’s private IP, this is already baked into GCP.
Google Cloud Platform (GCP) Virtual Private Cloud (VPC) networks have an internal DNS service that allows you to use instance names instead of instance IP addresses to refer to Compute Engine virtual machine (VM) instances.
Each instance has a metadata server that also acts as a DNS resolver for that instance. DNS lookups are performed for instance names. The metadata server itself stores all DNS information for the local network and queries Google's public DNS servers for any addresses outside of the local network.
[snip]
An internal fully qualified domain name (FQDN) for an instance looks like this:
hostName.c.[PROJECT_ID].internal
You can always connect from one instance to another using this FQDN.
Otherwise, if you want to serve up entirely arbitrary records to a set of machines, you’ll need to serve those records yourself (perhaps using Cloud DNS). In this case, you’d need to reconfigure the resolv.conf file on those instances appropriately (although you can’t just change the file as you see fit). Note that you can't restrict queries to only your own machines, but as David also mentioned, security through obscurity isn't security at all.
Google Cloud DNS Private DNS was just announced to beta and does exactly what you need
I just created a new site on my IIS on Amazon's EC2 and I was wondering if there is a way to access it publicly without assigning a domain.
In detail. I created a new site dev.example.com which is accessible when I am logged in my instance. Is there a way to access it outside by doing let's say 54.xxx.xx.xxx:80:dev.example.com
I don't know if that's even possible so any hints are appreciated
You can definitely do this, but here's what you'll need to do:
Make sure IIS is configured to route any incoming connection on a particular IP address to your site. This is distinct from IIS specifically listening for a particular hostname (e.g. mywebsite.com).
As an alternative to the above, you could also manually set your DNS on your local computer and then use your web browser to visit mywebsite.com. From IIS's perspective, a user will have requested mywebsite.com just as if public DNS were set
As far as the IP address you visit, your instance will either have an ephemeral Public IP Address which will be reset when the instance is stopped and started, or an Elastic IP Address, which persists across restarts.
As #Anthony Manzo mentioned, you'll need to make sure that your Security Group associated with this instance allows Port 80. In addition, you may want to disable Windows Firewall completely (or check that it allows Port 80 on all three "Zones" (Windows Firewall has 3 different zones to manage).
Afaik the IP addresses assigned to EC2 instances can change throughout its lifetime and therefore you should instead generate an Elastic IP Address (which will always direct to your instance). That way, you don't have to deal with DNS yourself and still are always able to connect to your instance.
Have a look at the "Security Groups" on the left hand of your EC2 web console. You'll have to allow TCP 80 (and whatever else) in the Security Group (probably 'default') first.
I have set up an EC2 instance and an Elastic IP which is associated to the instance. I have also set an A record in my DNS provider's Zone editor so that the domain name points to the elastic IP e.g. example.com = 123.123.123.123.
After reading many posts, this seems like it should be enough to work but my domain name still isn't resolving. I can't even ping the IP address! Weirdly I CAN ssh into the EC2 instance via the elastic IP and everything seems fine, except that my domain name doesn't resolve to the EC2 instance!
Any thoughts?
DNS names take a while to propagate so that is probably your first issue.
Go to http://www.whatsmydns.net/ and enter your domain name. If all of the locations are returning with the correct ip then you can safely assume its not a DNS propagation issue.
Enable ICMP rules in the security group. If using the aws console create a new rule for "All ICMP" with a source of "0.0.0.0/0". Enabling this creates a security risk for your server so only enable this temporarily while testing. At this point you should be able to ping your instance.
If using HTTP or HTTPS enable the correct ports on the security group for those protocols and as long as the instance is configured correctly with Apache you should be up and running.
Please check your EC2 security group & make sure desired ports are open