[mrtg] MRTG 2.16.0 on RH ES 4.7 (Nahant Update 7) doesn't find PNG support

[Niall O'Reilly]

Hello.

Recently, we've built a new DHCP server, with our usual MRTG
instrumentation, on top of RedHat Enterprise Linux ES 4.7 
(Nahant Update 7), and have found that MRTG (2.16.0 with 
traditional rateup) is generating GIF instead of PNG files.  
This is a problem for us, as all our other MRTG boxes use PNG, 
and this is what the portal system which sits in front of them all 
expects.  As a result, we have broken links due to URLs ending in
".png" corresponding to filenames ending in ".gif".

We don't have this problem with ES 4.3.  It appears that, since
some subsequent upgrade to ES 4, the PNG support which the MRTG
build script expects to find is no longer included in the way
it used to be, and is either absent or unrecognized.

While we're working on resolving this, I wonder whether anyone
else has found the solution already?  I suspect that some RPM
related to 'gd' needs to be added -- perhaps 'gd-devel', as the
base RPM for 'gd' is already installed. 

No doubt we can bypass the problem by using RRDtool and an
acceptable front-end.  This isn't an applicable solution for us
at present, so please "save your breath to cool your porridge"
if this is what you would recommend.  I do want to do move over
to the "one true way", but only when I have worked out how not to 
lose some favourite features of the _traditional_ MRTG display.  

8-)

Thanks in advance for sharing any relevant experience.  If no-one
can help, one of us will report our results in due course.

Happy Christmas and New Year!

Niall O'Reilly
University College Dublin IT Services