Archive for April, 2008

This week's developments

Monday, April 28th, 2008

It’s just over a week since the last update, and thanks to being away from work for a few days, I’ve had plenty of time to hack away at Ruby.

  • Milestone – the 100th check-in!
  • Unit tests for some of the models, a process which is remarkably straightforward and I’m really surprised I didn’t grok how easy this was before now.
  • SNMP proxy functionality is now working – this requires perl, SNMP.pm and a collection of MIB files. Remember to start external/snmp_proxy.pl!
  • Database changes – the iftype association is gone, since this was a hack to get around Ruby’s lack of MIB-parsing.
  • Model changes – device models now have get_oid and get_table methods which use the SNMP proxy, providing a useful abstraction from the guts of the SMP proxy.
  • UI changes – the interface layout has been refreshed.

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SNMP Proxies

Monday, April 28th, 2008

For better or worse, there’s now an SNMP proxy in NetHorus, written in perl and using XML-RPC.  Ruby purists will despise me, but I have my reasons for doing it this way, and they’re all centred around functionality.

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On Ruby and SNMP

Tuesday, April 22nd, 2008

In the beginning, NetHorus was called NETMAN, written in PHP and Perl.  I tried to rewrite the project entirely in Perl using Catalyst in 2006, but failed through a lack of time and available books on Catalyst.  That’s not to say Catalyst is a bad framework – far from it – but I wanted something a little more ‘me’.

My decision to re-code in Ruby using Rails wasn’t too difficult, although SNMP support was a major concern.  SNMP.pm for Perl is awesome – feature-rich, supported, quick… all the things that Ruby’s only SNMP implementation isn’t, despite what its website proclaims.

Right now, I’m at the stage where I could develop snmp.rb, bolt on MIB parsing using libsmi, then struggle down the path of implementing SNMPv3, and lose sight of what I’m really supposed to be doing.  Or, I could think of another way – such as using XML-RPC, possibly with BEEP, to an SNMP proxy written in Perl which then dispatches requests.

In a quick brainstorming session at $DAYJOB, I came up with some advantages to handing off SNMP to another device:

  • SNMP doesn’t work terribly quickly over high latency paths, so why not use a TCP-based connection as far as possible, and do all the SNMP donkey-work closer to the other endpoint?
  • Anything other than SNMPv3 isn’t encrypted in the slightest, and not everyone has the infrastructure to ensure an encrypted path between an SNMP manager and an SNMP agent.  Put the proxy on a remote device if you want, and suddenly it becomes easier.
  • Embedded devices behind firewalls.  Your network suddenly becomes a little easier to manage…

So that’s where it’ll go.  It’s not as light as SNMP, but it’s more extensible than what Ruby has to offer.  The SNMP proxy doesn’t have to be written in perl either.

For now, I’m concentrating on the basic functionality of getting single and multiple OIDs, and walking tables.  The rest will come later.

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This week's developments

Sunday, April 20th, 2008

Despite a very busy week in my day job, progress has continued.  Here’s a summary of the last week or so’s progress:

  • Interface types – these now work without the unpleasant override of :foreign_key.  This is a bit of a hack, setting iftype.id to be self.iana_iftype, but it gets around being unable to unprotect the :id column in ActiveRecord.  Sometimes you want to play with fire.
  • Visual tidyups – the admin layout has been removed, and I’ve removed the ugly HTML redirect to /welcome.  There’s also a prettier layout with some colours and the NetHorus logo, and a welcome message when on the main index.
  • Search function – it is now possible to search for a device or interface based on hostname, interface name, interface description or IPv4 address.
  • Device images – the inventory function will try to guess what type of device it is inventorying, based on the sysServices.0 OID.  Currently, Layer 3 switches and Routers are identified, but detection of which device is which may be a little flaky.
  • Device features – the framework for managing specific functions on devices, such as OSPF on a router that supports it, or BGP, or MPLS, has been written. Features will appear in a drop-down box on the management page for a device.  Be aware that nothing uses this functionality yet…
  • Event logs – when a device is inventoried, an event is logged against the device.  This will be extended to include other events, such as SNMP traps or detected errors on interfaces.
  • Internal stuff – some of the database migrations had the same names as previous migrations, so were never called.  This has been tidied up.

I’m on holiday this week and next, so expect my laptop to be by my side on train journeys and plenty more updates produced.  Here’s some of the things I’m hoping to be able to do:

  • Oracle support – thanks to Oracle Database 10g Express Edition.  If this works successfully, expect to see this as a supported backend.  PostgreSQL will follow.
  • SNMP proxy – since Ruby’s SNMP support doesn’t extend to interpreting SMI data (MIB files, basically), I’m going to write a proxy in Perl – which somebody could re-code in to C or C++ if they wished. This will accept SOAP calls and take away the need to handle SNMP in Ruby itself.  Tangential benefits of this could mean that SNMP proxies could be installed ‘closer’ to target devices.
  • BGP and OSPF support – using the features framework.  A view of BGP peers and OSPF neighbours would be awesome.

Please keep the feedback coming in to peter.hicks@poggs.co.uk – without it, I won’t know what features other people consider popular!

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Gathering speed

Friday, April 11th, 2008

So much has happened over the past week. I can’t quite believe how straightforward Rails is. It isn’t without its problems, but most of them are down to the author’s growing knowledge rather than Ruby itself.

In summary:

  • Devices now show a ‘last inventory’ timestamp to help identify when they were last inventoried
  • ActiveRecord editing/searching/browsing works as it should
  • IPv4 network names are looked up and displayed next to IPv4 addresses, e.g. “192.168.1.5 – Home Network”. The closest match is chosen based on netmask.
  • Device inventorying has been simplified – there is now just one inventory function which will be extended as necessary, and a ‘delete inventory’ function for when you want to clear information about a device from the database.

As usual, lots of database changes, so please rake db:migrate when you check out the latest code from Subversion.

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April Update

Friday, April 4th, 2008

So, what’s been going on?

  • Layer 3 interfaces are now probed correctly, but there’s still work to do so that changes are correctly identified.
  • A lot of database schema changes – remember to ‘rake db:migrate’ before checking out a new version from Subversion
  • The concept of ‘sites’ for devices and subnets is gradually being introduced
  • Views are being tidied up

Oracle support is still in the pipeline, as is the IPv4 database and searching. But it’s looking good so far, and I’m trying my best to ensure that the Subversion repository always contains a working copy of NetHorus.

Finally, have a look at http://trac.nethorus.org/ – I’m going to use this for issue tracking.

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