Hi Dachshund,
(chiming in as /me being is involved in the Debian project. I'm not involved
in maintaining net-snmp though)
Am Wed, Feb 24, 2021 at 01:59:03PM -0800 schrieb Dachshund Digital:
So, Raspberry Pi OS, latest of this date, only has Net-SNMP 5.7.3 available
in the official repository.
The package owner of the Debian 10 (Buster) package for Pi OS, has not
updated the official package for a very long time as well, it appears.
(One important correction: RaspianOS != Debian. Is is "just" derived
from Debian but there are many differences as well. But you can run
Debian on a Pi. I will talk about Debian below, it is likely that this
at least partly not applicable to RaspianOS, for example I dont know if
they roll a backport or testing suite.)
I think you a refering to Debian stable, likely Debian 10 (buster), as
buster has 5.7.3. For stable releases, the Debian promise is stability:
stable releases will generally not get new upstream versions. This is
why buster is "only" at 5.7.3.
If you look at https://tracker.debian.org/net-snmp, you'll see the
package has been updated since then. Testing is at 5.9 testing will
become the next stable, once ready; Debian is currently freezing, Debian
11 (bullseye) is expected to be released sometime this summer)
I figured I should be able to compile 5.9, which I downloaded and compiled
using the posted instructions on Source Forge. Other than the tweak for
shared library issue, and a few compiler warnings, the make and make install
worked fine. I did have to add the libperl-dev package as well. but I
suspect that is only because running ./configure I accepted all the
defaults, which includes the Perl support?
But I have a few questions outstanding.
1) Is there a better way to upgrade to 5.9? Right now I have 5.7.3 and 5.9
both, which I don't really need.
While you can of course compile yourself and install on Debian, it is
not recommended, for the reasons described here:
https://wiki.debian.org/DontBreakDebian
Compiling yourself and make install it will likely cause troubles down
the road, latest when you apt update to a new package version.
Your options could include (in no particular order)
- Filing a bug in the Debian BTS asking for a "backport".
- Downloading the new Debian-package source and doing a backport yourself
(basically get the debian package sources and try to make a package out
of it;)
- Waiting for bullseye to be released.
(Backports are described here: https://backports.debian.org/)
- If you feel experienced enough and ready to fix stuff if broken:
(For a Pi this might be feasible, as you could backup your SD card
before trying; otherwise this'd be not recommended)
- As Debian is currently freezing, cherry-picking net-snmp from the
"testing" distribution might be an alternative.
- you might even give "testing" a spin
2) Since I already had the current official package installed,
/etc/snmp/snmpd.conf existed, is there anything new or special under 5.9
that is different from 5.7.3 in the snmpd.conf of key importance? Ran
snmpconf -g basic_setup, to generate a newer conf file, seems to work fine,
I did not setup any OID restrictions.
Before make install-ing anything, you should remove (or even purge, but
backup the config before!) the Debian packages. But after make install,
there is no guarantee that you'll be able to install the packages again
without $fixing, though unlikely if you go for /usr/local or /opt.
3) I had to make a small change to the unit file for snmpd, to match the one
referenced in the 5.9 sources. This change included changes to the path and
the command line parameters for snmpd. Can someone please explain why the
drastic change in the command line parameters used with 5.7.3, but not 5.9?
For example... Original 5.9 unit file I had to change the path...
(systemd unit snipped)
Yes, in your use case this change is correct.
The path is because of the local rebuild and make install. (According to
the Linux FSH, software not from the distribution should go to
/usr/local or /opt) So the default from net-snmp is sane.
Am Wed, Feb 24, 2021 at 08:26:25PM -0800 schrieb Bart Van Assche:
On 2/24/21 1:59 PM, Dachshund Digital wrote:
Type=simple
#ExecStart=/usr/sbin/snmpd -f
ExecStart=/usr/local/sbin/snmpd -f
The snmpd path is set at configure time. If you want snmpd to be
installed into the /usr/sbin folder, please add --prefix=/usr to the
configure options (the default is --prefix=/usr/local).
Please don't for a local build. This will make going back to the
official Debian packages harder.
And the 5.7.3 unit file was quite different, especially the command line
parameters for snmpd...
Hmm ... I'm not aware of any command-line parameter changes?
3) I have done a few basic snmp queries, and so far so good, I think.
Anything I am missing here? Interesting that the snmpd.conf location
has changed to /usr/local/share/snmp/.
Please add --prefix=/usr to the configure options to make snmpd read
snmpd.conf from /usr/share/snmp.
See above.
Beside that, according to the FSH configuration is expeced in /etc… So
the Debian package ships it in /etc/snmpd/snmpd.conf. The /usr hierachy
should be considered to be read-only. (and even be shared between
hosts.)
Am Wed, Feb 24, 2021 at 09:39:07PM -0800 schrieb Dachshund Digital:
Bart,
Thanks for the reply. Very informative.
One question... Since I accepted all the defaults... and use the official
configuration tool? Should it not default to the correct path for the conf
file?
Also, the 5.9 unit file has 'snmpd -f' as the only parameter. But the debian
5.7.3 package has the following...
snmpd -Lsd -Lf /dev/null -u Debian-snmp -g Debian-snmp -I
-smux,mteTrigger,mteTriggerConf -f -p /run/snmpd.pid
Maybe the package owner customized? Specification appears to customize
logging, set UID and GID values (not sure what these address from memory),
don't fork shell (same as 5.9) and specify the PID file.
Yes, this is the Debian integration part: My guesses are that Debian
creates the user/group Debian-snmp when installing the package, so that
snmp has not to be run as root. and it is not forking, because this is
how you should do it in systemd unit files.
FWIW, the systemd service file in the Debian package is maintained here:
https://salsa.debian.org/debian/net-snmp/-/blob/master/debian/snmpd.service
