limes

README

Limes

Limes provides an easy work flow with MFA protected access keys, temporary credentials and access to multiple roles/accounts.

Limes is a Local Instance MEtadata Service and emulates parts of the AWS Instance Metadata Service running on Amazon Linux. The AWS SDK and AWS CLI can therefor utilize this service to authenticate.

Warning

The AWS SDK refreshes credentials automatically when using limes. So all services will change profile if the profile is changed in limes.

Installation

1. Download binary for your architecture from https://github.com/otm/limes/releases/latest
2. Copy the file to /usr/local/bin or appropriate location in PATH
3. Make it executable: chmod +x /usr/local/bin/limes
4. Linux: Allow limes to bind to privileged ports setcap 'cap_net_bind_service=+ep' /usr/local/bin/limes

Note: On Mac OS limes server is needed to run as root for the time being.

Configuring the Loop Back Device

The configuration below adds the necessary IP configuration on the loop back device. Without this configuration the service can not start.

Note: This configuration is not persistent between reboots.

Linux

sudo ip addr add 169.254.169.254/24 broadcast 169.254.169.255 dev lo:metadata
sudo ip link set dev lo:metadata up

Mac

sudo /sbin/ifconfig lo0 alias 169.254.169.254

Configuring IAM (Identity and Access Management)

To be done

Configuring IMS (Instance Meta-data Service)

There is an example configuration file. The configuration file is documented. Make a copy of the file and place it in ~/.limes/config.

mkdir -p ~/.limes
wget -O ~/.limes/config https://raw.githubusercontent.com/otm/limes/master/config.example

Use your favorite text editor to update ~/.limes/config

Usage

Running limes in your terminal prints usage information.

Starting the Service

The service is started with limes start.

Assuming Profiles

A profile is assumed with limes profile <profile-name>, where profile-name is a configured profile. Please note that this does not refer to AWS profiles but profiles configured in limes.

Service Status

By running limes status it is possible to see the current status, and also it can detect common problems and misconfigurations.

Known Problems

If AWS environment variables, .aws/credentials or .aws/config are present there is a chance that the limes does not work. This can be checked with limes status

Security

The service should be configured on the loop back device, and only accessible from the host it is running on.

Note: It is important not to run any service that could forwards request on the host running Limes as this would be a security risk. However, this is no difference from the setup on an Amazon Linux instance in AWS. If an attacker could forward requests to 169.254.169.254/24 your credentials could be compromised. Please note that an attacker could utilize a DNS to resolve to this address, so always be aware where you forward requests to.

Roadmap

• Add support for running commands
• Add support for providing MFA with client to enable to start as a service
• Add support for temporary move/remove AWS configuration files
• Add support for exporting environment variables
• Windows support (If I get someone to test it)

Build

To build you need a Go compiler and environment setup. See https://golang.org/ for more information regarding setting up and configuring Go.

go get github.com/otm/limes
go build

If protobuf definitions are updated run:

go generate