The current NetSolve has been modified in a way that servers can be registered as a Hardware/Software server, a Hardware server, or a Software server.
When a server is started it is by default a Hardware/Software server. It provides it's own problems to other machines of the same architecture as Software server but can also execute problems from other machines of the same architecture. But if a user wants to provide newly created functions without donating his hardware resources to a NetSolve pool he can install the new problem to a server on his machine and start it with the -s option. So the agent will add the problem to the repository and when someone wants to execute it the binary will be transfered to a Hardware server and executed there.
When a user starts a server without the -s option (the default), the machine becomes available to any NetSolve user for execution of his problem. The agent then adds this server to the database in the hardware server list. It also knows the architecture of the hardware server. Thus if the client submits a request, the agent can make a better decision whether to use this hardware server or not. If other servers are overloaded, it can select this hardware server as a potential server.
When the client makes a request, the agent creates a mapping of the software server containing the particular software with all the hardware servers with the same architecture. Thus, the return value from the agent contains a mapping of hardware and software servers.
The client then contacts the hardware server with the set of input data. The transfer of the software is done automatically. The hardware server contacts the software server and fetches the software.
The software is dynamically transferred from the software server to the hardware server. This however is done only once, when the software arrives at the hardware site, the hardware server can cache the software. The hardware server administrator decides the caching policy. Currently, the hardware server can cache a maximum of 10 problems, and after that it removes the problem on LRU basis.
To mark a problem as non-moveable, i.e., the problem cannot be moved by the Hardware/Software server feature to another server, use the:
Due to the software transfer between the Software Server to Hardware Servers there exists a need to ensure the code being transfered can be trusted. Security is important to prevent any malicious code from being executed on the Hardware Server. Keeping this in mind, the NetSolve team has implemented a security mechanism in NetSolve using GPG.
GnuPG stands for GNU Privacy Guard and is GNU's tool for secure communication and data storage. It can be used to encrypt data and to create digital signatures. It includes an advanced key management facility and is compliant with the proposed OpenPGP Internet standard as described in RFC 2440. As such, it is aimed to be compatible with PGP from NAI, Inc. For more information on GPG, consult http://www.gnupg.org
Within the scope of NetSolve, Software providers are able to sign software using keys signed by the NetSolve Admin (or others if they choose to). The Hardware Server provider would be able to specify trustworthy parties, using GPG trust framework. By default, the hardware server trusts the NetSolve Admin. Thus to take advantage of software transfer, both the parties should have GPG and should enable the software transfer. NetSolve provides a good level of flexibility in the implementation of Hardware-Software feature and GPG.
There are 2 main cases:
CASE 1: GPG is disabled
In this case, the user has GPG disabled. Hence, the software (problem) will not be transfered by the Software Server nor will the software be transfered to the Hardware Server. This is the default NetSolve mechanism.
CASE 2: GPG is enabled
In this case, the default software, provided in the original NetSolve distribution will not be transfered. (See PDFs in $NETSOLVE_ROOT/problems directory). This is done by having MOVABLE set to 0 in the PDF. However, if the server admin decides to make new software, and have that software moveable (transferable), then he needs to set MOVABLE to 1 in the PDF.
A problem with MOVABLE set to 1 must be signed to run, even on the server that it is located on.
In order for movable code to be accepted by Netsolve hardware servers, the code must be signed. In order to sign code you must have a GPG key that is trusted by the Netsolve hardware servers. There are three steps to getting this key
generating the key
getting the key signed by someone the netsolve hardware server trusts
incorporating the signed key into your keyring
Generating the key
First, verify that you have gpg 1.2.3 or later installed.
(1) DSA and ElGamal (default) (2) DSA (sign only) (5) RSA (sign only) Your selection?
What keysize do you want? (1024)
Requested keysize is 1024 bits Please specify how long the key should be valid. 0 = key does not expire <n> = key expires in n days <n>w = key expires in n weeks <n>m = key expires in n months <n>y = key expires in n years Key is valid for? (0)
2. Getting the key signed
First you need to export your key. This can also be done directly using gpg or with the provided script, NS_export_key. NS_export_key takes two parameters, first your key id, you can use the email address that you entered above, followed by the name of the file you wish to export to.
UNIX>NS_export_key email@example.com yourkey.gpg
UNIX>gpg --export firstname.lastname@example.org > yourkey.gpg
3. Incorporating the signed key in your keyring
Finally when you get the signed key back in the mail, save it in a file (call it signedkey.gpg) and import it into your keyring. Again, this can be done two ways, directly using gpg or with the provided script, NS_import_key. NS_import_key takes one parameter, the file containing your signed key.
UNIX>gpg --import signedkey.gpg
4. Signing problems
A script called NS_sign_problem is used to sign problems once they are compiled and linked. To use it, type
UNIX>NS_sign_problem problem-filename key-id
UNIX>NS_sign_problem service-superlu email@example.com
By default, a NetSolve hardware server will not accept mobile code. In order for the server to accept mobile code it has to be configured to use gpg to verify the authenticity and integrity of code.
If you configure your hardware server to run gpg, by default the hardware server will accept any code which is either:
signed by firstname.lastname@example.org
signed by a third party whose key is signed by email@example.com
This section describes how to change which keys your server trusts. In order for your server to trust a signature, the following conditions are necessary
that key is trusted by the server
that key is signed by someone the server trusts
"firstname.lastname@example.org" is trusted ultimately
"email@example.com" is trusted fully
NetSolve's copies of GPG files
The NetSolve server maintains its own copies of gpg files (pubring.gpg, secring.gpg, trustdb.gpg). It does this so that there is no conflict between NetSolve's use of gpg and ordinary personal uses of gpg. A user which is trusted to sign someone's key for email might not be trusted to sign netsolve code. These files are stored in a directory that the NetSolve server finds using the environment variable GPGHOME.
There is a program named ns-gpg which is used to affect keys used by the NetSolve server instead of the keys ordinarily used by gpg. It is just a shell script that calls gpg with additional options. You use it to mainipulate keys and trust parameters just like you would use gpg.
How to change the default trust parameters
If you wish to change the default trust parameters, you must go through the following steps:
delete the netsolve-hardware-server key
create your own key for the hardware server
decide whether to trust netsolve-master key
1. Delete the netsolve-hardware-server key
UNIX>gpg --delete-key netsolve-hardware-server
2. Create your own key for the hardware server
To avoid conflicts, the name of the key should be an email address that you control. It's also occasionally handy if the person who runs the server can be reached by sending email to the address. However it might also be desirable for that address to NOT be the normal address of the user who runs the NetSolve hardware server. For example, it might be useful to set up an alias named firstname.lastname@example.org that gets forwarded to email@example.com.
3. Decide how much to trust the netsolve-master key
If you want your hardware server to be able to accept code signed by other netsolve developers that we (the primary developers) trust, you will need to change the parameters to trust the netsolve-master key. (By default this key was trusted but that's because it was signed by the netsolve-hardware-server key, which you have deleted. Having created your own key, you now need to re-establish trust from that key in the netsolve-master key.)
If you want to trust the netsolve-master key you must do two things:
sign the key
change the trust parameters in the key to indicate that it is trusted
If you do not want to trust it, you should not sign the key. But you should change the parameters anyway (to indicate that you don't trust it) just to be sure. To sign the key, do:
UNIX>gpg --sign-key netsolve-master
To change the trust parameters, do:
UNIX>gpg --edit-key netsolve-master
----------------------------------------------------------------------- pub 2048R/AABD3F7C created: 2003-07-12 expires: never trust: f/f (1). NetSolve Master Key <firstname.lastname@example.org> -----------------------------------------------------------------------
pub 2048R/AABD3F7C created: 2003-07-12 expires: never trust: f/f ^ | this says how much you trust this key ------------------------------+
- means never set q means don't know n means do NOT trust m means trust marginally f means trust fully u means ultimate trust (i.e. this is you)
----------------------------------------------------------------------- Please decide how far you trust this user to correctly verify other users' keys (by looking at passports, checking fingerprints from different sources...)? 1 = Don't know 2 = I do NOT trust 3 = I trust marginally 4 = I trust fully 5 = I trust ultimately m = back to the main menu -----------------------------------------------------------------------
Select "4" if you wish to trust problems that have been signed by people whose keys are signed by netsolve-master. (i.e. people that the netsolve developers trust)
Note that if you wish to trust code that is signed directly by netsolve-master, but NOT trust code that is signed by keys that were signed by netsolve-master, you should sign netsolve-master's key but NOT trust netsolve-master as an introducer.
How to list keys
To list the keys that the NetSolve server knows about, do:
How to add a key to NetSolve server's keyring
The person whose key you want to add needs to send it to you in a file. He can extract it into a file by doing:
UNIX>gpg --export key-id > key.gpg
UNIX>gpg --import key.gpg
How to delete a key
UNIX>gpg --delete-key key-id