OpenSSH is a freely available version of the SSH connectivity tools, and is the standard version of SSH used by many linux distributions. See http://www.openssh.org/ for more information.
Contents
1. Overview
No current version of OpenSSH currently natively supports moonshot, but patches are available for v5.3 and v5.9 of OpenSSH to fix the issues that stop it from working. Ultimately we hope that these patches will become a standard part of OpenSSH, so that OpenSSH will work without any extra work being necessary.
2. Compatibility
2.1. Key
In the tables below, the following icons have the following meanings:
- This version of the software has been tested and verified as supporting Moonshot.
- This version of the software has been tested and verified as not supporting Moonshot.
- This version of the software has not yet been tested thoroughly and its status is not known. Let us know if you have tried it and whether it worked or not!
2.2. Compatibility List
Note that accessing supported versions of this software requires a Moonshot compatible client - see the next section for details on which clients are supported.
Any versions not listed below list have not yet been tested. If you do so, please let us know!
OS version | Compatible? | Packages Available? | Notes |
---|---|---|---|
CentOS 6 | Using our pre-compiled package. Re-compiling instructions available. | ||
CentOS 7 | Using our pre-compiled package. | ||
Debian 7 | Using our pre-compiled package. | ||
Debian 8 | Building instructions available. | ||
RHEL 6 | Using our pre-compiled package. Re-compiling instructions available. | ||
RHEL 7 | Using our pre-compiled package. | ||
Scientific Linux 6 | Using our pre-compiled package. Re-compiling instructions available. | ||
Scientific Linux 7 | Using our pre-compiled package. | ||
Ubuntu 12.04 LTS | Using our pre-compiled package for Debian 7 | ||
Ubuntu 14.04 LTS | Building instructions available. |
3. Installation & Configuration Instructions
How you set up a Moonshot-enabled version of the OpenSSH server will differ depending on your OS. See the relevant pages for your particular distribution:
4. Client Compatibility
The following clients are known to work with this server software using Moonshot authentication (click on the link to see further information about enabling Moonshot in that client):
5. Next Steps
Once you have installed the software, what happens next?
5.1. Configuration Instructions
Once installed, the Moonshot-enabled OpenSSH server will still need a few quick tweaks in order to turn on the Moonshot support.
Ensure that the certificates referenced in
/etc/radsec.conf
can be read by the SSH user:$ su - --shell=/bin/bash sshd $ cat path_to_ca.pem $ cat path_to_client.pem $ cat path_to_client.key
If they cannot be read by the SSH user, add the SSH user to the group that can read the certificates.
Configure the OpenSSH server to use Moonshot by editing
/etc/ssh/sshd_config
. Check the following lines are present and uncommented:GSSAPIAuthentication yes GSSAPIKeyExchange yes GSSAPIStrictAcceptorCheck yes
GSSAPIStrictAcceptorCheck
If your SSH server has a different hostname to the one given publicly (for example. you have CNAME entries you give to your users instead of the internal name), you should turn
GSSAPIStrictAcceptorCheck
off. Disabling the check defaults it to yes.Restart the OpenSSH server
Configure the OpenSSH Client.
5.2. Account Mapping
5.2.1. Mapping to an account specified in a SAML attribute
Moonshot uses Shibboleth libraries to parse RADIUS and SAML attributes - SAML assertions can be embedded inside RADIUS responses by the IdP, allowing an IdP to exercise a very fine-grained authorisation policy. One potential use of this is to allow the Moonshot IdP to specify which account the user should log in to your SSH server as. To do this, it passes across a username in a SAML attribute and your server maps that to a local user account (via local-login-user).
Edit
/etc/shibboleth/shibboleth2.xml
and insert the following lines if they don't exist (note that this should go directly after the opening<SPConfig ... clockSkew="180">
stanza:<Extensions> <Library path="plugins.so" fatal="true" /> </Extensions>
Edit /etc/shibboleth/attribute-map.xml and find the SAML attribute that the Moonshot IdP will be sending you that contains the username.
Example
We want to map from the incoming SAML2 representation of "eduPersonEntitlement"
<Attribute name="urn:oid:1.3.6.1.4.1.5923.1.1.1.7" id="entitlement"/>
Change the id of the attribute to "local-login-user".
Example
We change the attribute defining the SAML2 representation of "eduPersonEntitlement" such that its id becomes "local-login-user"
<Attribute name="urn:oid:1.3.6.1.4.1.5923.1.1.1.7" id="local-login-user"/>
In the standard Moonshot distribution, SSH will look for local-login-user to determine who to authenticate the user as. This attribute mapping will be managed by the XML assertion in the FreeRADIUS reply for a successful authentication.
5.2.2. Mapping to an account specified in a RADIUS attribute
Moonshot uses Shibboleth libraries to parse RADIUS and SAML attributes. Like the above SAML option, Moonshot can parse a RADIUS attribute (such as the User-Name
attribute) and your server maps that to a local user account (via local-login-user
).
Edit
/etc/shibboleth/shibboleth2.xml
and insert the following lines if they don't exist (note that this should go directly after the opening<SPConfig ... clockSkew="180">
stanza:<Extensions> <Library path="plugins.so" fatal="true" /> </Extensions>
Then find the line
<AttributeExtractor type="XML" ...>
further down in the file, duplicate it and modify the duplicate as follows:<AttributeExtractor type="GSSAPI" validate="true" reloadChanges="false" path="attribute-map.xml">
You may want to store your GSSAPI attributes in a separate file. In this case, amend the path above to the new file.
Edit /etc/shibboleth/attribute-map.xml and find the first attribute line that does not use an AttributeDecoder.
Example
We will duplicate the incoming SAML2 representation of "eduPersonEntitlement"
<Attribute name="urn:oid:1.3.6.1.4.1.5923.1.1.1.7" id="entitlement"/>
Duplicate the line. The name format for GSSAPI attributes is somewhat different. It does not use the OID namespace; instead it uses the IETF namespace. The attribute name is also different.
Example
We change the attribute defining the SAML2 representation of "eduPersonEntitlement" such that its id becomes "local-login-user" and it uses a different namespace
<GSSAPIAttribute name="urn:ietf:params:gss:radius-attribute 1" id="local-login-user"/>
The numeral 1 in the name of the attribute refers to RADIUS attribute 1, which is the User-Name. A more extensive compendium of attribute numbers is available at IANA's number registry.
In the standard Moonshot distribution, SSH will look for local-login-user to determine who to authenticate the user as. This attribute mapping will be managed by the XML assertion in the FreeRADIUS reply for a successful authentication.
5.2.3. Further mapping options
To Come!