How to get the IP address of RDS instance in AWS - amazon-web-services

I got the same answer everywhere on the internet regarding my question of how to get the IP address of an RDS instance in AWS, but I don't know what dig is, and how to use it.
How to allocate IP address in VPC to RDS instance?
Please help me find the IP address of my RDS instance in AWS?

It won't display the ip address on the configuration page for the RDS instance because RDS IP's are dynamic in nature. You can dig for them if you need them but you would be better server using the DNS endpoint for the instance. This remains static and can be found on the details tab of the RDS instance within AWS.

The IP address of your AWS instance will be the IP address of the RDS instance.
If your hostname of your AWS instance is blah.blah.amazonaws.com then you can use the dig command (on Linux machines) or ping command on both Windows and Linux to find out the IP address of the host:
ping blah.blah.amazonaws.com
This will give you back the IP address of the host (something like this):
c:\ping www.google.com
Pinging www.google.com [216.58.210.100] with 32 bytes of data:
Reply from 216.58.210.100: bytes=32 time=14ms TTL=58
Reply from 216.58.210.100: bytes=32 time=15ms TTL=58
Reply from 216.58.210.100: bytes=32 time=14ms TTL=58
So the IP address of www.google.com is 216.58.210.100. dig will give you more output but the IP address is also in there. But sometimes the actual IP address of your AWS instance is actually in the hostname itself. For example:
ip-12-34-56-78.us-west-2.compute.internal
The IP address 12.34.56.78 is already in the name (depending on your instance). You can find the hostname in the AWS Console/Dashboard.

Use this:
SELECT inet_server_addr();

Simple method to find RDS ip address: Open command prompt from local machine and ping your RDS Endpoint. You will see the reply from destination host ip address. That is your RDS ip address! Regardless if it is public accessible or not.

The answer given by Paolo Bolla is good, but only works for Postgresql.
For Microsoft SQL Server, please use:
SELECT
local_net_address = ConnectionProperty('local_net_address')
, local_tcp_port = ConnectionProperty('local_tcp_port')

You can also use Nslookup <<RDS SQL Server>> command to figure out the IP address as suggested in this AWS blog post.

dig is command-line utility that finds an IP address a domain name leads to.
You can simply install it using :
apt-get update && apt-get install dnsutils -y
Then to find an IP of RDS instance (with endpoint xxx.yyy.us-east-1.rds.amazonaws.com), run the following command :
dig xxx.yyy.us-east-1.rds.amazonaws.com
In the output of dig, you will be able to find IP address in ANSWER SECTION :
;; ANSWER SECTION:
xxx.yyy.us-east-1.rds.amazonaws.com. 5 IN A 172.30.1.253
As you can see RDS instance endpoint, resolved to A type of DNS record with Private IP address

On AWS Management Console - Location : AWS Management Console -> EC2 -> Network & Security, Network interfaces
You can see all of IP addresses and its resource's details on description tab together.

Related

EC2 Redhat - Multiple Private IP

I have one VPC with two Subnets (SubnetA and SubnetB).
My team wants to have multiple IPs assigned to the Instance, each from one subnet.
The Instance already have one Private IP (from SubnetA, Primary one) when I launched it, then I attached another Private IP from another SubnetB via the Console Attach network Interface option.
I can see both of the IPs in the console under Managed IP Address option.
I rebooted the Instance, and I was expecting to see both of the IPs when I do ifconfig, but I can see only the Primary one.
To cross-check if the Private IP is actually attached to the Instance, I queried Instance Metadata using the following commands :
curl -s http://169.254.169.254/latest/meta-data/network/interfaces/macs/02:14:46:91:bc:34/local-ipv4s
curl -s http://169.254.169.254/latest/meta-data/network/interfaces/macs/02:1d:2a:75:ax:04/local-ipv4s
I can see both of the IPs in the output for the above two commands respectively.
I checked the status of NETWORKMANAGER systemctl status NetworkManager
It was stopped
I started the Service and enabled NetworkManager automatically at boot time, using following commands:
systemctl start NetworkManager
systemctl enable NetworkManager
Then I checked the output of ifconfig
This time it showed me both of the MAC addresses, with the only difference for the second one I was not able to see the IP address. So basically the interface is up, so the underlying device is found. There is no IP address associated with this interface.
So I tried both of the options to associate IP:
Assign an IP address manually:
sudo ifconfig ens6 w.x.y.z
Or contact the DHCP server, if it exists, and let it provides an IP address for the interface:
sudo dhclient -v ens6
Both of them worked and I can see both of the IPs under inet.
The last problem was I have to do this every time I reboot the Instance.
So I was trying to add a permanent route using the following command:
sudo /sbin/route add default gw 1xx.xx.2xx.193
Here the IP is the second IP from the SubnetB, but I am getting the error :
SIOCADDRT: Network is unreachable
To solve the above problem what I did is, I was already having a file with
/etc/sysconfig/network-scripts/ifcfg-ens5 with details for Primary IP, I added one more file
/etc/sysconfig/network-scripts/ifcfg-ens6 with the necessary details for secondary IP
This is what I referred.
Rebooted and it is working.
But I am not able to ping the secondary IP.
I think I have to add one more Gateway from the second subnet but not sure about this.
What else needs to be done so that I can route traffic, ping, ssh using the Secondary IP.
Please refer to my VPC Subnet CIDRS:
Subnet A: 1.7.2.128/26
Subnet B: 1.7.2.192/26
Output of ip route:
Update:
Today when I started the server I am able to ping the Secondary IP(200), but not the Primary one(136), from one of my test Instances. Also, ssh is done using Primary IP.
ip route add default via 1XX.XX.XXX.X9X dev ens6 table 2000;
ip route add 1XX.7X.2XX.X9X dev ens6 table 2000;
ip rule add from 1XX.7X.2XX.1XX lookup 2000;
The above command helps me to resolve this issue and I am able to ping my secondary IP.
To make this configuration persist after reboots, the same commands, I have added into rc.local
In the first line, the IP is the Gateway IP (Second IP in the Subnet Range)
The IP mentioned in the second and third lines in the command is the actual Secondary IP of my Server.

Is it possible to change the hostname of AWS SSH command?

By default AWS EC2 instances are accessible using something like this
ssh -i "key.pem" ubuntu#ec2-00-00-00-00.us-east-2.compute.amazonaws.com
Is it possible to change that to something along the lines of:
ssh -i "key.pem" ubuntu#ec2-00-00-00-00.myowndomain.com
Sorry if this is a noob question, I just can't figure out what to even Google. I either get tutorial about SSHing in or tutorial about running websites on an EC2 - neither helpful.
If you have your own domain name, then:
Assign an Elastic IP address to the instance, which is a static IP address (it won't change if the instance is stopped and started)
In your DNS system that controls your Domain Name, create a CNAME record for the subdomain (eg app.mydomain.com) that points to the Elastic IP address
As long as both ec2-00-00-00-00.us-east-2.compute.amazonaws.com and ec2-00-00-00-00.myowndomain.com resolve to the same IP, you will have no accessibility issue with the underlying instance.

AWS EC-2 check the domain is linked correctly with the public IP address

I have an EC-2 Instance and a domain name. I've added A record and couple of CNAME records in DNS management service where I bought the domain name. I've put my AWS instance's Public IP address as the value in those records. I want to know how can I check that domain is now correctly linked or not to the my instance?
I mean if there is a way to check that domain is succesfully linked with my instance. I know then there is no problem with domain selling guys and I only need to check with nginx and AWS settings to debug issues.
How do I know this?
You can run ping command from your terminal or command line if you are in windows.
[noones#noones ~]$ ping google.com
PING google.com (216.58.203.174) 56(84) bytes of data.
64 bytes from bom07s11-in-f14.1e100.net (216.58.203.174): icmp_seq=1 ttl=55 time=53.0 ms
64 bytes from bom07s11-in-f14.1e100.net (216.58.203.174): icmp_seq=2 ttl=55 time=51.1 ms
you will see your ec2 instance ip address on ping response. As we are seeing 216.58.203.174 on above google.com domain
To check whether your DNS is completely resolved use Dnschecker sites.
If it is resolved and still you're not able to reach your site. Kindly go through nginx logs in var/log/nginxlogs and also check you're having proper nginx configurations

Resolve URL to AWS Server

I have a domain that I own. I will say is example.com. I added SSO.example.com as a Type A record on GoDaddy with a value of 37.89.245.2(example).
The IP address is a elastic IP on a Windows AWS server.
I can ping the IP address but I can't ping the URL. Do I need to do something with the IP address on the AWS Windows server to be able to ping the URL?
This is pretty much one of my first web based projects so any help would be appreciated!
Ping is not a reliable test method in AWS because most security groups do not permit inbound ICMP protocol, which is used by Ping. So, if you really want to test connectivity, do it on a port that you actually need your application to support, such as HTTP (80) or trying an SSH/RDP connection.
Another common use for a Ping is to resolve the domain name to an IP address, since it displays the result on-screen. This can be a good way to check that your Amazon Route 53 configuration is correct. (Same as a dnslookup.)
I was jumping the gun a bit and the new NameServers I was using had not replicated completely yet. After replication completed everything was able to be pinged successfully.

Why do you need to change the Hostname of your EC2 instance?

There is a topic in EC2 documentation Changing the System Hostname. Why does one need to change it? Just for fun? Just to have some nice shell prompt?
// change this
ubuntu#ip-123-12-1-231 ~ $
// to this?
ubuntu#my-beautiful-hostname ~ $
I'm learning how AWS DNS work, where my EC2's DNS lives that resolves a default Public DNS name to Public IP address of my instance
Public DNS: ec2-xx-xx-xxx-xx.ap-southeast-2.compute.amazonaws.com
Public IP: xx-xx-xxx-xx
And how can I host multiple apps with real domain names (example1.com, example2.com, so on) in one EC2 instance, how to modify and manage DNS. And actually I don't know what to read about it in docs, and read everything related to hostnames and DNS, and found this topic Changing the System Hostname and don't understand why would one want to change a hostname and if it can be valuable info for me.
UPD:
And now a real a practical question for those specimens who like closing questions quietly.
Where does a DNS live in EC2 instance? How is Public DNS mapped to Public IP? Where is that record in my EC2 Ubuntu instance? Is Route53 involved in it?
Where does a DNS live in EC2 instance?
It doesn't, DNS resolution use by the server is set in /etc/resolv.conf and /etc/nsswitch.conf. The hostname domain name for that server is set (Redhat derived systems) in /etc/sysconfig/network
How is Public DNS mapped to Public IP?
With a DNS record
Where is that record in my EC2 Ubuntu instance?
In the DNS for the domain that you have attached it to
Is Route53 involved in it?
Only if you are using Route53 for DNS
EC2 DNS location (source):
In EC2-Classic, the Amazon DNS server is located at 172.16.0.23.
In EC2-VPC, the Amazon DNS server is located at the base of your VPC network range plus two.
For more information, see Amazon DNS Server in the Amazon VPC User Guide
Well i had the same issue as you did and someone replied me this
It isn't a huge deal if you are just running a single server, mostly
to help you identify a server with local networking. Some things like
mail servers will use your hostname unless you specify otherwise.
This is an example of somewhere I saw that done
My original query
why do some people set hostname and some dont? whats the use?
hostnamectl set-hostname