Update a security group adding a rule for SSH from the current IP.

update_sg_ip.sh

#!/bin/bash

## Simple script to update the security group to allow ssh access from current IP.
## You can specify the Public DNS name of the instance that you want to access 
## and it will update the first SG found. You can also setup a default SG and 
## the script will update it and the DNS name is not informed.

SG="sg-xxxxxxxx"
REGION="us-east-1"

if [ "$#" -ne 1 ]; then
    echo "Using default security group '$SG'"
    echo "You can provide a full EC2 hostname to update a SG for this host. Ex: update_sg_ip.sh ec2-54-76-190-252.eu-west-1.compute.amazonaws.com"
else
    REGION=`echo $1 | cut -d. -f2`
    echo "Region identified: $REGION"
    SG=`aws ec2 describe-instances --region $REGION --filters "Name=dns-name,Values=$1" --query "Reservations[0].Instances[0].NetworkInterfaces[0].Groups[0].GroupId"`
    echo "SG found: ${SG//\"}"
fi

ip=`curl -s https://api.ipify.org`
echo "Your current IP: $ip"
aws ec2 authorize-security-group-ingress --protocol tcp --port 22 --cidr $ip/32 --group-id ${SG//\"} --region $REGION