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150 changes: 150 additions & 0 deletions README.rst
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# aws-mfa: Easily manage your AWS Security Credentials when using Multi-Factor Authentication (MFA)


**aws-mfa** makes it easy to manage your AWS SDK Security Credentials when Multi-Factor Authentication (MFA) is enforced on your AWS account. It automates the process of obtaining temporary credentials from the [AWS Security Token Service](http://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html) and updating your [AWS Credentials](https://blogs.aws.amazon.com/security/post/Tx3D6U6WSFGOK2H/A-New-and-Standardized-Way-to-Manage-Credentials-in-the-AWS-SDKs) file. Traditional methods of managing MFA-based credentials requires users to write their own bespoke scripts/wrappers to fetch temporary credentials from STS and often times manually update their AWS credentials file.

The concept behind **aws-mfa** is that there are 2 types of credentials:

* `long-term` - Your typcial AWS access keys, consisting of an `AWS_ACCESS_KEY_ID` and `AWS_SECRET_ACCESS_KEY`

* `short-term` - A temporary set of credentials that are generated from a combination for your long-term credentials and your MFA token using the [AWS Security Token Service](http://docs.aws.amazon.com/STS/latest/APIReference/Welcome.html).


**aws-mfa** uses your `long-term` credentials in combination with your MFA device serial and token to populate the short term credentials section. Your short term credentials can be thought of as the credentials that are actively used.

#### Installation:

###### Option 1

`pip install aws-mfa`

###### Option 2

1. Clone this repo
2. `python setup.py install`


#### Credentials File Setup

In a typical AWS credentials file, credentials are stored in sections, denoted by a pair of brackets: `[]` The `[default]` section stores your default credentials. You can store multiple sets of credentials using different profile names. If no profile is specified, the **default** section is used.

Long term credential sections are identified by the convention `[<profile_name>-long-term]`. Short term credentials are identified by the typical convention: `[<profile_name>]`. The following illustrates how you would configure you credentials file using **aws-mfa** with your default credentials:

```
[default-long-term]
aws_access_key_id = YOUR_LONGTERM_KEY_ID
aws_secret_access_key = YOUR_LONGTERM_ACCESS_KEY

```

After running `aws-mfa`, your credentials file would read:

```
[defult-long-term]
aws_access_key_id = YOUR_LONGTERM_KEY_ID
aws_secret_access_key = YOUR_LONGTERM_ACCESS_KEY


[default]
aws_access_key_id = <POPULATED_BY_AWS-MFA>
aws_secret_access_key = <POPULATED_BY_AWS-MFA>
aws_security_token = <POPULATED_BY_AWS-MFA>
```

Similarly, if you utilize a credentials profile named **development**, your credentials file would look like:

```
[development-long-term]
aws_access_key_id = YOUR_LONGTERM_KEY_ID
aws_secret_access_key = YOUR_LONGTERM_ACCESS_KEY

```

After running `aws-mfa`, your credentials file would read:

```
[development-long-term]
aws_access_key_id = YOUR_LONGTERM_KEY_ID
aws_secret_access_key = YOUR_LONGTERM_ACCESS_KEY


[development]
aws_access_key_id = <POPULATED_BY_AWS-MFA>
aws_secret_access_key = <POPULATED_BY_AWS-MFA>
aws_security_token = <POPULATED_BY_AWS-MFA>
```


##### Usage

```
usage: aws-mfa [-h] [--device arn:aws:iam::123456788990:mfa/dudeman]
[--duration DURATION] [--profile PROFILE]
[--assume-role arn:aws:iam::123456788990:role/RoleName]
[--role-session-name ROLE_SESSION_NAME]

optional arguments:
-h, --help show this help message and exit
--device arn:aws:iam::123456788990:mfa/dudeman
The MFA Device ARN. This value can also be provided
via the environment variable 'MFA_DEVICE`.
--duration DURATION The duration, in seconds, indicating how long the
temporary credentials should be valid. The minimum is
900 seconds (15 minutes) and the maximum is 3600
seconds (1 hour). This value can also be provided via
the environment variable 'MFA_STS_DURATION'.
--profile PROFILE If using profiles, specify the name here. The default
profile name is 'default'
--assume-role arn:aws:iam::123456788990:role/RoleName
The ARN of the AWS IAM Role you would like to assume,
if specified. This value can aslo be providedvia the
environment variable 'MFA_ASSUME_ROLE'
--role-session-name ROLE_SESSION_NAME
Friendly session name required when using --assume-
role.
```
Argument precedence: Command line arguments take precedence over environment variables.
### Usage Example
Run **aws-mfa** *before* running any of your scripts that use any AWS SDK.
```
$> aws-mfa --duration 1800 --device arn:aws:iam::123456788990:mfa/dudeman
INFO - Using profile: default
INFO - Your credentials have expired, renewing.
Enter AWS MFA code for device [arn:aws:iam::123456788990:mfa/dudeman] (renewing for 1800 seconds):123456
INFO - Success! Your credentials will expire in 1800 seconds at: 2015-12-21 23:07:09+00:00
```

Running again while credentials are still valid:

```
$> aws-mfa --duration 1800 --device arn:aws:iam::123456788990:mfa/dudeman
INFO - Using profile: default
INFO - Your credentials are still valid for 1541.791134 seconds they will expire at 2015-12-21 23:07:09
```

Using environment variables:

```
export MFA_DEVICE=arn:aws:iam::123456788990:mfa/dudeman
export MFA_STS_DURATION=1800
$> aws-mfa
INFO - Using profile: default
INFO - Your credentials have expired, renewing.
Enter AWS MFA code for device [arn:aws:iam::123456788990:mfa/dudeman] (renewing for 1800 seconds):123456
INFO - Success! Your credentials will expire in 1800 seconds at: 2015-12-21 23:07:09+00:00
```

##### With Profiles

```
$> aws-mfa --duration 1800 --device arn:aws:iam::123456788990:mfa/dudema --profile development
INFO - Using profile: development
Enter AWS MFA code for device [arn:aws:iam::123456788990:mfa/dudema] (renewing for 1800 seconds):666666
INFO - Success! Your credentials will expire in 1800 seconds at: 2015-12-21 23:09:04+00:00
```
218 changes: 218 additions & 0 deletions aws-mfa
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#!/usr/bin/env python

import argparse
try:
import configparser
except ImportError:
import ConfigParser as configparser
import datetime
import logging
import os
import sys

import boto3

logger = logging.getLogger('botomfa')
stdout_handler = logging.StreamHandler(stream=sys.stdout)
stdout_handler.setFormatter(
logging.Formatter('%(levelname)s - %(message)s'))
stdout_handler.setLevel(logging.DEBUG)
logger.addHandler(stdout_handler)
logger.setLevel(logging.DEBUG)

AWS_CREDS_PATH = '%s/.aws/credentials' % (os.path.expanduser('~'),)


def main():
STS_DEFAULT = 900
parser = argparse.ArgumentParser()
parser.add_argument('--device',
required=False,
metavar='arn:aws:iam::123456788990:mfa/dudeman',
help="The MFA Device ARN. This value can also be "
"provided via the environment variable 'MFA_DEVICE`.")
parser.add_argument('--duration',
type=int,
help="The duration, in seconds, indicating how long "
"the temporary credentials should be valid. The "
"minimum is 900 seconds (15 minutes) and the maximum "
"is 3600 seconds (1 hour). This value can also be "
"provided via the environment variable "
"'MFA_STS_DURATION'.")
parser.add_argument('--profile',
help="If using profiles, specify the name here. The "
"default profile name is 'default'",
required=False)
parser.add_argument('--assume-role',
metavar='arn:aws:iam::123456788990:role/RoleName',
help="The ARN of the AWS IAM Role you would like to "
"assume, if specified. This value can aslo be provided"
"via the environment variable 'MFA_ASSUME_ROLE'",
required=False)
parser.add_argument('--role-session-name',
help="Friendly session name required when using "
"--assume-role.",
required=False)
args = parser.parse_args()

if not os.path.isfile(AWS_CREDS_PATH):
sys.exit('Could not locate credentials file at %s' % (AWS_CREDS_PATH,))

if not args.device:
if os.environ.get('MFA_DEVICE'):
args.device = os.environ.get('MFA_DEVICE')
else:
sys.exit('You must provide --device or MFA_DEVICE')

if not args.duration:
if os.environ.get('STS_DURATION'):
args.duration = int(os.environ.get('STS_DURATION'))
else:
args.duration = STS_DEFAULT

if not args.assume_role:
if os.environ.get('MFA_ASSUME_ROLE'):
args.assume_role = os.environ.get('MFA_ASSUME_ROLE')

config = configparser.RawConfigParser()
config.read(AWS_CREDS_PATH)

validate(args, config)


def validate(args, config):
short_term_name = 'default'
if args.profile:
short_term_name = args.profile

long_term_name = '%s-long-term' % (short_term_name,)
logger.info('Using profile: %s' % (short_term_name,))

try:
key_id = config.get(long_term_name, 'aws_access_key_id')
access_key = config.get(long_term_name, 'aws_secret_access_key')
except configparser.NoSectionError:
logger.error(
"Long term credentials session '[%s]' is missing. "
"You must add this section to your credentials file "
"along with your long term 'aws_access_key_id' and "
"'aws_secret_access_key'" % (long_term_name,))
sys.exit()
except configparser.NoOptionError as e:
logger.error(e)
sys.exit()

# Validate presence of short-term section
if not config.has_section(short_term_name):
if short_term_name == 'default':
configparser.DEFAULTSECT = short_term_name
if sys.version_info.major == 3:
config.add_section(short_term_name)
config.set(short_term_name, 'CREATE', 'TEST')
config.remove_option(short_term_name, 'CREATE')
else:
config.add_section(short_term_name)
get_credentials(short_term_name, key_id, access_key, args, config)
else:
try:
expiration = config.get(short_term_name, 'Expiration')
exp = datetime.datetime.strptime(expiration, '%Y-%m-%d %H:%M:%S')
diff = exp - datetime.datetime.utcnow()
if diff.total_seconds() <= 0:
logger.info("Your credentials have expired, renewing.")
get_credentials(
short_term_name, key_id, access_key, args, config)
else:
if config.getboolean(short_term_name, 'assumed_role'):
logger.info('You are assuming the role: %s'
% (config.get(
short_term_name, 'assumed_role_arn')))
logger.info(
'Your credentials are still valid for %s seconds'
' they will expire at %s'
% (diff.total_seconds(), expiration))
except configparser.NoOptionError:
logger.info("Your credentials are invalid, renewing.")
get_credentials(short_term_name, key_id, access_key, args, config)


def get_credentials(short_term_name, lt_key_id, lt_access_key, args, config):
try:
token_input = raw_input
except NameError:
token_input = input

mfa_token = token_input('Enter AWS MFA code for device [%s] '
'(renewing for %s seconds):' %
(args.device, args.duration))

client = boto3.client(
'sts',
aws_access_key_id=lt_key_id,
aws_secret_access_key=lt_access_key
)

if args.assume_role:
if args.role_session_name is None:
logger.error("You must specify a role session name "
"via --role-session-name")
sys.exit()
response = client.assume_role(
RoleArn=args.assume_role,
RoleSessionName=args.role_session_name,
DurationSeconds=args.duration,
SerialNumber=args.device,
TokenCode=mfa_token
)
config.set(
short_term_name,
'assumed_role',
'True',
)
config.set(
short_term_name,
'assumed_role_arn',
args.assume_role,
)
else:
response = client.get_session_token(
DurationSeconds=args.duration,
SerialNumber=args.device,
TokenCode=mfa_token
)
config.set(
short_term_name,
'assumed_role',
'False',
)
config.remove_option(short_term_name, 'assumed_role_arn')

# aws_session_token and aws_security_token are both added
# to support boto and boto3
options = [
('aws_access_key_id', 'AccessKeyId'),
('aws_secret_access_key', 'SecretAccessKey'),
('aws_session_token', 'SessionToken'),
('aws_security_token', 'SessionToken'),
]

for option, value in options:
config.set(
short_term_name,
option,
response['Credentials'][value]
)
# Save expiration individiually, so it can be manipulated
config.set(
short_term_name,
'expiration',
response['Credentials']['Expiration'].strftime('%Y-%m-%d %H:%M:%S')
)
with open(AWS_CREDS_PATH, 'w') as configfile:
config.write(configfile)
logger.info(
'Success! Your credentials will expire in %s seconds at: %s'
% (args.duration, response['Credentials']['Expiration']))

if __name__ == "__main__":
main()
2 changes: 2 additions & 0 deletions setup.cfg
@@ -0,0 +1,2 @@
[bdist_wheel]
universal = 1
10 changes: 10 additions & 0 deletions setup.py
@@ -0,0 +1,10 @@
from setuptools import setup

setup(
name='aws-mfa',
version='0.0.1',
description='Manage AWS MFA Credentials',
author='Brian Nuszkowski',
scripts=['aws-mfa'],
install_requires=['boto3>=1.2.3']
)

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