nrpe and nrpe_nt development

[Stephen Strudwick]

I've been thinking about this a lot last night, about different ways to
implement private/public keys with open ssl to verify the nagios server is
the real one etc.

Ive decided in the end that for me the easiest approach is just to code in
a blowfish compile time option as I have BF code tried and tested that can
easily be added.

Im going to code this up over the next week or two, then the nagios
developers can then decide if they want to include it or not.

On a side note..

I had a minor arguement with someone at pipex who thought IP restrictions
should be enough, but I done some research and im pretty sure I could
spoof an IP using poisoned arp packets to pretend I am the nagios server,
(effectivly a man in the middle attack, ideally I would need to be on
the same lan to do this).

once I do that I could execute plugins on the server we are monitoring
and dos it or possibly exploit a plugin (although unlikely if not passing
arguements).

I might try this next week as an experiment.

Adding some kind of authentication option to the security design would
just make it that bit harder for anyone to exploit.

I have to be really careful because we tend to be under constant attack
from malicous people being a fairly big UK isp.

-
Stephen Strudwick
Advanced Development Engineer
Development Group, Product Development
PIPEX Communications
http://www.pipexcommunications.net/

Mobile: 07906 191256
Direct: 020 8957 1217

On Thu, 18 Dec 2003, Subhendu Ghosh wrote:

> A nice balancing act is what is needed :)
>
> my 2 cents.
>
> I like the configure time option of including blowfish even at the risk of
> additional conifguration requirements.  Since check_nrpe is only available
> thru the NRPE distribution, blowfish doesn't add an extra requirement for
> the general plugin dist.
>
> I like being able to send ARGx to the remote plugins via NRPE.
>
> Lastly - if nrpe_nt is to flourish, we need a repository for the Windows
> specific plugins. My feeling is that this should be both a binary and a
> source repository as not all windows system will have the requisite
> toolset.
>
> -sg
>
>
> On Thu, 18 Dec 2003, Stephen Strudwick wrote:
>
> >
> > > This also goes back to whether you are allowing check_nrpe to execute argument$
> > > For security we don't we only allow defined checks to run with no arguments and
> > > most agree that is the safer option. If there is a feeling that the server
> > > should be authenticated by the clients using a cert then that is something I
> > > can work on putting in place without much heartache and we would just need to
> > > automate the creation of self signed certs in the make process to simplify the
> > > procedure.
> >
> > When we have run netsaint in the past with nrpep we had command line
> > arguements, but I planned to stop doing this with nagios mainly because I
> > thought it wes unecessary complication as well as a security risk.
> >
> > We do need more security than the basic IP checks here at pipex because we
> > cant be sure our servers will have tcp wrappers on them (mainly NT is the
> > problem here) or be behind a firewall.
> >
> > we have to be as sure as we can (to the poiht of maybe being too zealous)
> > that the servers are not compromised in any way.
> >
> > > If there is a feeling that the server
> > > should be authenticated by the clients using a cert then that is something I
> > > can work on putting in place without much heartache and we would just need to
> > > automate the creation of self signed certs in the make process to simplify the
> > > procedure.
> >
> > something like this would be really good, if you point me in the right
> > direction im willing to code something over xmas, because im working to a
> > early jan deadline :(
> >
> > I really want to make sure whatever is done is accepted into the code base
> > so that our operations people can always download the latest version from
> > the site and not use a hacked about version that instantly becomes
> > static in development.
> >
> > -
> > Stephen Strudwick
> > Advanced Development Engineer
> > Development Group, Product Development
> > PIPEX Communications
> > http://www.pipexcommunications.net/
> >
> > Mobile: 07906 191256
> > Direct: 020 8957 1217
> >
> > On Thu, 18 Dec 2003, local.coder wrote:
> >
> > >
> > > Stephen,
> > >
> > > When coding in the encyrption the idea was to secure the data between the nagios
> > > server and the remote client. The use of passwords and other options were
> > > specifically removed to keep out problems with plaintext password management
> > > and other fun. This is meant as a data protection scheme only and not an
> > > authentication scheme. The IP Address restriction for us is enough to limit
> > > remote hosts. With some minor changes the openssl part could be setup to use
> > > pre-shared certs but when talking with others that went to a level of
> > > complexity that seemed overwhelming for large server bases and updates. I
> > > originally was working with the blowfish encryption but at Ethan's and plugin
> > > people's request moved to openssl since it is already included in other plugins
> > > as a requirement and there was a concern to keep external requirements to a
> > > minimum if possible.
> > >
> > > This also goes back to whether you are allowing check_nrpe to execute arguments.
> > > For security we don't we only allow defined checks to run with no arguments and
> > > most agree that is the safer option. If there is a feeling that the server
> > > should be authenticated by the clients using a cert then that is something I
> > > can work on putting in place without much heartache and we would just need to
> > > automate the creation of self signed certs in the make process to simplify the
> > > procedure.
> > >
> > > Like I say I didn't want to have static passwords in the config files for
> > > authentication because to me that gave a false sense of bad security.
> > >
> > > Derrick
> > >
> > >
> > > Quoting Stephen Strudwick <sas at pipex.net>:
> > >
> > > >
> > > > I also forgot to add that I've written a load of plugins for nrpe_nt in C
> > > > such as check disk, eventlog, cpu load, mem load, services etc.
> > > >
> > > > I will release the source and binaries as soon as we have finished testing
> > > > on them.
> > > >
> > > > -
> > > > Stephen Strudwick
> > > > Advanced Development Engineer
> > > > Development Group, Product Development
> > > > PIPEX Communications
> > > > http://www.pipexcommunications.net/
> > > >
> > > > Mobile: 07906 191256
> > > > Direct: 020 8957 1217
> > > >
> > > > On Thu, 18 Dec 2003, Stephen Strudwick wrote:
> > > >
> > > > > hello all,
> > > > >
> > > > > This is my first post to this list and I want to ask some questions
> > > > > about my company (Pipex) doing some development for nrpe and nrpe_nt.
> > > > >
> > > > > We have been using netsaint for a while and are upgrading to nagios and
> > > > > have decided to use nrpe for nt and unix boxes.
> > > > >
> > > > > I noticed the encryption using openssl is not really that secure, as far
> > > > > as I can tell it only encrypts the session between the client and server
> > > > > and dosnt stop anyone else with the nrpe client querying the server.
> > > > >
> > > > > The only protection the demon has as far as I can tell is the IP
> > > > > restrictions.
> > > > >
> > > > > We have some internal code we have been using for several years here that
> > > > > provides Blowfish encryption using shared keys, username pass
> > > > > authentication and all kinds of handshaking and security.
> > > > >
> > > > > The code is in C, and we have modules for *nix and NT.
> > > > >
> > > > > we also have an implementation as a Perl module (with C backend code).
> > > > >
> > > > > I would like to add this code to nrpe as a compile time option (say
> > > > > --use-blowfish on ./configure).
> > > > >
> > > > > And also to the NT version.
> > > > >
> > > > > If I add this code I would like if possible to be integrated into the
> > > > > current releases of nrpe so we dont create a static fork inside our
> > > > > company).
> > > > >
> > > > > Basically im looking for feedback as to whether this is neccessary/right
> > > > > thing to do, or have I misunderstood the openssl encryption.
> > > > >
> > > > > I envisage the shared key encryption working like nrpep with a -s
> > > > > <secret> option being used for a secret on the nagios server.
> > > > >
> > > > > Thanks in advance for any feedback.
> > > > >
> > > > > -
> > > > > Stephen Strudwick
> > > > > Advanced Development Engineer
> > > > > Development Group, Product Development
> > > > > PIPEX Communications
> > > > > http://www.pipexcommunications.net/
> > > > >
> > > > >
> > > > >
>
> --
>
>
>
>
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