Public Repository

Last pushed: a year ago
Short Description
hardened ssh jump host based on latest fedora stable
Full Description


Provide docker-based development environments to support
100-500 concurrent workspaces on a single server. The idea
is for developers to edit code and perform
light compilation or testing within the workspace.

  • Serious testing is the duty of a continuous integration server.
  • Serious compilation is the duty of a build server.

Please add any issues you find with this software
to the upstream wormhole.

Architectural considerations<br/>
OVAL vulnerability scan<br/>
Test harness<br/>
User instructions<br/>
Admin instructions<br/>

Architectural considerations

source: docs/


  • User data lives in a data container and
    persists across upgrades of the app container.

  • sshd is restrictive:

    • ssh host key persists across upgrades of the app container.
  • Weak firewall allows:

    • inbound from Internet to wormhole ephemeral TCP ports
    • outbound from wormhole to Internet on all ports
  • Strong firewall allows:

    • inbound from wormhole IP to internal TCP 22
    • no outbound connections other than return traffic for inbound connections
  • Must be capable of running on CoreOS. Therefore no outside dependencies.

  • Internal infrastructure should use appropriate access control mechanisms
    based on risk evaluation of the wormhole.

OVAL vulnerability scan

The Red Hat Security Response Team provides OVAL definitions
for all vulnerabilities (identified by CVE name) that affect RHEL or Fedora.
This enables users to perform a vulnerability scan and
diagnose whether the system is vulnerable.

The Dockerfile in this repo adds a script to download the latest
OVAL definitions from Red Hat and perform a vulnerability scan
against the image. If the image has one or more known vulnerabilies,
the script exits non-zero, and the docker build fails.


  • We must resolve all known vulnerabilities
    in order to successfully build an image.

  • The scan is time-dependent as of image build, so
    we should rebuild the image when Red Hat updates the OVAL feed.

  • The vulnerability scan is distinct from the SCAP secure configuration scan
    described by the test harness.

It is possible to scan an existing image:

docker run --rm -t jumanjiman/wormhole /usr/sbin/

The exact output of the vulnerability scan varies according to the
latest Red Hat OVAL feed, but it looks similar to this snapshot from August 2014:

-snip copious checks-

RHSA-2014:1051: flash-plugin security update (Critical)

RHSA-2014:1052: openssl security update (Moderate)

RHSA-2014:1053: openssl security update (Moderate)

vulnerability scan exit status 0

TODO: Implement some sort of CD system to poll the OVAL feed and rebuild
the image on any update. may be
a candidate for the solution.

Test harness

RSpec documents key behaviors and assures no regressions:

contributor friction
  there should not be any

  should use correct docker API version
  image should be available
  image properties
    should expose ssh port and only ssh port
    should have volume /home/user
    should have volume /media/state/etc/ssh

admin scripts
  given user handle="booga"
    everybody knows pubkey
    booga knows privkey
  ` $handle "$pubkey"` creates wormhole from 2 containers
    "booga-data" is a persistent read-write container
      should exist
      should be stopped
      should be created from busybox
      should export /home/user volume read-write
      should export /media/state/etc/ssh volume read-write
      should not mount any volumes
    "booga" is a read-only app container
      should exist
      should be running
      should run unprivileged
      should be created from jumanjiman/wormhole
      should use volumes from booga-data
      should have hostname
      should be limited to 512 MiB RAM
      `docker logs` should show sshd running on sshd port
      should expose internal sshd port and only sshd port
      should map internal sshd port to an outside ephemeral port

arcanist (phabricator client)
  `arc` is in user path
  `arc version` is functional
  uses bash autocompletion

BZ1099206 (slow test)
  home directory should exist
  go get should work

user convenience
  man -k returns results
  locate returns the path for

  should resolve CVE-014-6271
  should resolve CVE-014-7169

  has command-line eiffel compiler in path
  has estudio in path

ldc D compiler
  compiles a D program (PENDING:

locale archive
  supports C
  supports POSIX
  supports en_US.utf8
  supports en_US.UTF-8

SCAP secure configuration checks (slow test)
  should pass all tests
  /etc/securetty should be a zero-size file

prohibited packages
  should not have at installed
  should not have prelink installed
  should not have sudo installed

prohibited commands
  should not have the at command
  should not have the crond command
  should not have the crontab command
  should not have the /usr/sbin/prelink command

rhc (openshift client)
  `rhc` is in user path
  `rhc --version` is functional

sshd config
    should use privilege separation
    should use pam
    should allow pubkeyauthentication
    should deny passwordauthentication
    should deny gssapiauthentication
    should deny kerberosauthentication
    should deny challengeresponseauthentication
  tunnels and forwarding
    should deny ssh tunnels
    should deny TCP forwarding
    should deny X11 forwarding
    should deny gateway ports
  Common Configuration Enumeration (CCE)
    CCE-3660-8 Disable remote ssh from accounts with empty passwords
    CCE-3845-5 idle timeout interval should be set appropriately
    CCE-4325-7 Disable SSH protocol version 1
    CCE-4370-3 Disable SSH host-based authentication
    CCE-4387-7 Disable root login via SSH
    CCE-4431-3 SSH warning banner should be enabled
    CCE-4475-0 Disable emulation of rsh command through sshd
    CCE-14061-6 "keep alive" msg count should be set appropriately
    CCE-14491-5 Use appropriate ciphers for SSH
    CCE-14716-5 Users should not be allowed to set env options
    should hide patch level

users with interactive shells
  should only include "root" and "user"
    "user" cannot su

Finished in 1 minute 6.35 seconds (files took 0.45472 seconds to load)
61 examples, 0 failures

The OpenSCAP secure configuration test shown above uses a
tailoring file
to adjust the upstream checks.
It expands to this inside the container:

Title   gpgcheck Enabled In Main Yum Configuration
Rule    ensure_gpgcheck_globally_activated
Result  pass

Title   gpgcheck Enabled For All Yum Package Repositories
Rule    ensure_gpgcheck_never_disabled
Result  pass

Title   Shared Library Files Have Restrictive Permissions
Rule    file_permissions_library_dirs
Result  pass

Title   Shared Library Files Have Root Ownership
Rule    file_ownership_library_dirs
Result  pass

Title   System Executables Have Restrictive Permissions
Rule    file_permissions_binary_dirs
Result  pass

Title   System Executables Have Root Ownership
Rule    file_ownership_binary_dirs
Result  pass

Title   Direct root Logins Not Allowed
Rule    no_direct_root_logins
Result  notchecked

Title   Virtual Console Root Logins Restricted
Rule    securetty_root_login_console_only
Result  pass

Title   Serial Port Root Logins Restricted
Rule    restrict_serial_port_logins
Result  pass

Title   Only Root Has UID 0
Rule    no_uidzero_except_root
Result  pass

Title   Log In to Accounts With Empty Password Impossible
Rule    no_empty_passwords
Result  pass

Title   Password Hashes For Each Account Shadowed
Rule    no_hashes_outside_shadow
Result  pass

Title   netrc Files Do Not Exist
Rule    no_netrc_files
Result  pass

Title   SSH Root Login Disabled
Rule    sshd_disable_root_login
Result  pass

Title   SSH Access via Empty Passwords Disabled
Rule    sshd_disable_empty_passwords
Result  pass

Title   SSH Idle Timeout Interval Used
Rule    sshd_set_idle_timeout
Result  pass

Title   SSH Client Alive Count Used
Rule    sshd_set_keepalive
Result  pass

User instructions

New containers begin life with a git-suitable
This is only the initial bashrc; you can modify it at any time.

Inside the container, your user account is literally named user.
That means, with default build options, your prompt inside the container is:


Connect to your container with info provided by admin:

ssh -i path/to/privkey -p <your port> user@<ip>

Admin instructions

Edit global configuration

Clone this repo, then inspect and optionally modify global.conf.
When you build a user box for the first time, the build script
copies global.conf into /etc/wormhole/global.conf.

Edit duo configuration

This step is optional. The default configuration does not use Duo.
If you want to use Duo Security for multi-factor authentication,
you must edit both global.conf and login_duo.conf.

  • When you build your first user box (see below), these two files
    are copied into /etc/wormhole/.

  • If you modify /etc/wormhole/*.conf, you must restart the user
    app container(s).

Build a user box

Use the build script with a unique user id (such as github handle)
and the user ssh pubkey to create a runtime container:

pubkey="ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEArSm80/8UD/eMolUXU3j6geyNrxthnQxbE4dpwRhXU+F6fbQG+wk9SdWev9NcLLWg9a4zBUSMJUXrrU/8ik3WshSpZpqQary4ZiFFQKgSfYriouchc20S3wwFQZcbOJgH5t5wgGeNaDMzc2GRFhqbuuBiBBF+W5llk0X9CGE1o1iAlyVPAn4UfrJ4//5OXMhYwmU+fO9df3y5Kpn/0SY/lRwWuZeVVIXC+nZcFYXNzPyBVTNEooOXLVXivddtU82jfp65ggTMdLfUafZqia1/smfWQP23lU8F4ySayAOa1lhXXvrGtpxl3lu7vaSvdEg7+F4YaIhxnWZqt769joDraw== pmorgan@github"

./ $user "$pubkey"

:warning: The build script attempts to fetch the github user's
ssh pubkeys and place them into the data container as authorized keys.
This is really bad if you create a devenv for somebody based on
a name that is not their github handle and the name is a valid
github handle for somebody else!

A runtime container should be up on a random ssh port:

$ docker ps

CONTAINER ID        IMAGE               COMMAND                CREATED             STATUS              PORTS                   NAMES
689479673e8e        jumanjiman:latest   /bin/sh -c /usr/sbin   About an hour ago   Up About an hour>22/tcp   jumanjiman

The build script depends on systemd and enables a "wormhole@<username>"
service to start at boot-time for the container you just created and
persists the port as an environment variable in /etc/wormhole/<username>.conf.
For example: If the username is jumanjiman, you can run
sudo systemctl status wormhole@jumanjiman to see:

● wormhole@jumanjiman.service - jumanjiman app container
   Loaded: loaded (/etc/systemd/system/wormhole@.service; enabled)
   Active: active (running) since Wed 2014-06-18 14:08:05 UTC; 3h 18min ago
 Main PID: 701 (docker)
   CGroup: /system.slice/system-wormhole.slice/wormhole@jumanjiman.service
           └─701 /usr/bin/docker run --rm -t -m 512m --volumes-from jumanjiman-data -p 49153:22 -h --name jumanjiman...

Jun 18 14:08:05 ip-192-168-254-21 bash[478]: jumanjiman
Jun 18 14:08:05 ip-192-168-254-21 systemd[1]: Started jumanjiman app container.
Jun 18 14:08:09 ip-192-168-254-21 docker[701]: Server listening on port 22.
Jun 18 14:08:09 ip-192-168-254-21 docker[701]: Server listening on :: port 22.

:warning: The default global.conf limits each app container to 512 MiB memory.
You can override this for a single user in /etc/wormhole/<username>.conf.

You can view the current limit for a container via the sys filesystem.
For example, here is a container that was started with a 1 MiB limit:

$ cat /sys/fs/cgroup/memory/lxc/<hash>/memory.limit_in_bytes

If a PID inside a container gets killed due to the memory limit,
you can view details in dmesg output.


Create a local file called jumanjiman-data.tar with contents of
user data container.

./ jumanjiman

Restore user data container from backup

./ jumanjiman

Upgrade user app container

Rebuild the jumanjiman/wormhole image as described above, then...

./ jumanjiman

Destroy a user app+data container

Backup, then discard both the app and data containers for a user.

./ jumanjiman

Build an image for the app container

This image serves as a template for an app container.<br/>
You can build the image locally:


Trigger a rebuild-and-test cycle to get latest updates:

cd wormhole/
date > REBUILD
git add REBUILD
git commit -m 'test build with latest package updates'
# Open pull request.

:warning: Use CoreOS to build image.

Fedora kernel on DigitalOcean
has an older LXC implementation that leads to inconsistent builds.
For example, it sometimes builds the base image with bad perms on
/var and other directories that must be 0755.

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