On m=E5n, 2006-11-20 at 07:19 -0800, Steve Friedl wrote:
> Hi folks,
> =

> While sniffing around for information on smux today, I found that
> agent/mibgroup/README.smux was really out of date.
> =

> Though GateD may have been the impetus for smux support in ucd-snmp,
> it's a dead project now: it went to closed source, and is not nearly as
> functional as other routing protocol daemons such as Quagga/Zebra.
> =

> So I decided to do a little rewriting to reduce the focus on GateD, as
> well as to steer people to AgentX instead. I didn't *entirely* remove
> the GateD (or ucd) mentioned out of a respect for history, but at least
> this page looks like it's been superficially maintained.
> =

> With the caveat that this is the first time I've even *touched* an smux
> configuration, and that I don't really know what I'm doing, is this page
> any more out-of-it than the original?
> =

> If this is ok, I'll submit a patch in the usual manner.
> =

> Steve
> =

> --- =

> Stephen J Friedl | Security Consultant | UNIX Wizard | +1 714 544-6561
> www.unixwiz.net | Tustin, Calif. USA | Microsoft MVP | steve@unixwiz.net
> =

> #------------------------------------------------------------------------
> =

> [1] What is SMUX?
> =

> SMUX is the snmp multiplexing protocol (RFC 1227). It can be used by an
> snmp agent to query variables maintained by another user-level process.
> =

> [2] Why is it relevant to net-snmp?
> =

> The original ucd-snmp agent needed a mechanism to query statistics from
> GateD. GateD has traditionally supported this functionality via SMUX.
> Hence SMUX was implemented within the ucd-snmp framework to extract
> routing protocol statistics from GateD.
> =

> net-snmp continues to support smux, and many applications still use it.

Here I think a little elaboration could be in place - I am not aware of
any applications other than gated/zebra/quagga that do use the SMUX

> [3] What is GateD?
> =

> GateD is the 'Gateway Daemon' which implements a variety of routing
> protocols on a variety of platforms (OSes). This was formerly available
> as open source, but has since been made closed and entirely un-free.
> Other routing protocol daemons such a quagga (http://www.quagga.net)
> support SMUX.
> =

> [4] Can SMUX extract statistics from other user-level processes?
> =

> Yes, the current implementation allows for the registration of any MIB
> that might be registered by a SMUX peer.
> =

> [5] How does it work?
> =

> Assuming 'snmpd' is already up and running, when the SMUX peer comes up,
> it identifies itself with an oid identifier and string password, and
> registers any MIBs it would like to implement. When 'snmpd' receives
> queries for these MIBs, it passes these queries to the peer.
> =

> [6] Who implemented SMUX for ucd-snmp?
> =

> SMUX was implemented by Rohit Dube. He had oodles of help from
> ucd-snmp-coders (Dave, Niels, Wes, Simon, Felix, Leonti) and gated-people
> (Acee, Feiyi, Larry, Sue). [If I missed somebody, sorry in advance and
> do let me know]. Later, Nick Amato re-write the entire SMUX package so
> the code today is mostly his.
> =

> [7] How do I find out more about SMUX?
> =

> Read the RFC and the code, mainly, but only for legacy code.
> =

> /New/ sub-agent development should instead use the AgentX subaprotocol,
> which is not only standardized (RFC 2741 + 2742), but is outright superior

Strictly speaking AgentX ain't no standard yet but I still agree that it
is a lot better than SMUX.

> to smux in a number of important ways (handles SET requests reliably,
> able to handle overlapping registrations, aware of SNMPv3 contexts, etc.)
> =

> Only build new smux support if you have to.

Very good advice.

In general I agree that this is a nice enhacement to the old file. Thank
you for taking the time to do the updating and sharing it with us.


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