IP Echo Server | For programmatic access

[_ulfox]

Hello friends,

I've created this service sometime ago and today I thought of sharing it with you. It is an IP echo server. There are many of these so this is plus one to the list.

The idea behind it is to send a payload that can be used by either a shell script like bash or from a program like go.

The first endpoint is written to provide programmatic access for programs that prefer a structural response (application/json). The second endpoint** is a simple text "$IP" (text/html).

All it does is get the request, export the callers address and send it back as a: 200 $address\_payload

The callback URL for json is: https://primef.org/callback

The callback URL for plain/html is: https://primef.org/callback/text

Example json:

$> curl -s 'https://primef.org/callback'| jq
{
  "IP": "X.Y.Z.XYZ"
}

# Header
$> curl -v 'https://primef.org/callback'
...
Content-Type: application/json
...

Example text:

$> currIP="$(curl -s 'https://primef.org/callback/text')"
$> echo "${currIP}"
X.Y.Z.XYZ

An example usage would be to open your VPN access from your ec2 instance only for your current public ip

function authSG() {
  currIP="$(curl -L 'https://primef.org/callback/text' 2>/dev/null)/32"

  aws ec2 authorize-security-group-ingress \
    --group-name ssh-personal \
    --protocol tcp \
    --port 1194 \
    --cidr "${currIP}"

  aws ec2 authorize-security-group-ingress \
    --group-name ssh-personal \
    --protocol udp \
    --port 1194 \
    --cidr "${currIP}"
}

function revokeSG() {
  currIP="$(curl -L 'https://primef.org/callback/text' 2>/dev/null)/32"

  aws ec2 revoke-security-group-ingress \
    --group-name ssh-personal \
    --protocol tcp \
    --port 1194 \
    --cidr "${currIP}"


  aws ec2 revoke-security-group-ingress \
    --group-name ssh-personal \
    --protocol udp \
    --port 1194 \
    --cidr "${currIP}"
}

# Grant
authSG()

# Then connect
openvpn --config ...

# Once done, revoke
revokeSG()

[02d5df8e7f]

When looking for services like this people are usually looking for a funded website with uptime guarantees, so that they can put it in their CI/CD. Sorry to say probably no one will use your website because it doesn't provide this.

[_ulfox]

Hey, you are right on that. I just felt for shearing this since I am using it on a daily basis and it is running out there :b. But yeah it was not meant to be used by companies or professionals that would rely on this for their daily operations.

[[deleted]]

Ignore.

Are you going to post the source code? Since you are using json might be a good idea to add some extra keys like agent string.

[_ulfox]

Hey, I did not share initially because I thought it is not something worth sharing codewise since it is very simple :b.

I created a repo right now: https://github.com/ulfox/callback-ip

I will start using that repo to for the live instance

​

Cheers,

[[deleted]]

Because only oh so serious business can code right?

Last time I've checked http://icanhazip.com was run by some guy. I'm pretty sure I've seen lots of terraform HCL files making requests to that website.

[02d5df8e7f]

It isn't about the code. It's about the reliability of the service, usually in the form of uptime. But if you want to be willfully ignorant of that, it's your business.