I am rebuilding an Icinga server that has been left behind by a previous employee. I have everything up and running, except for a bunch of MIB files for 3com switches that I cannot get to work.
The server is a CentOS 6 OpenVZ container.
In the original server there is a bunch of mib files in the default location at /usr/share/snmp/mibs/ and the 3com ones at /usr/share/snmp/mibs/3Com_4500/MIBs. The 3Com mibs work fine:
/usr/lib/nagios/plugins/check_snmp -H 10.10.111.11 -P 2c -C public -o hwDevMFanStatus.65536 -s "active(1)" -m A3COM-HUAWEI-LswDEVM-MIBSNMP OK - active(1) |
In the new server, the MIBs in the 3com folder do not get acknowledged and I get errors like the following:
/usr/lib/nagios/plugins/check_snmp -H 10.10.111.11 -P2c -C someuser -o hwDevMFanStatus.65536 -s "active(1)" -m A3COM-HUAWEI-LswDEVM-MIB
External command error: No log handling enabled - turning on stderr logging
Cannot find module (A3COM-HUAWEI-LswDEVM-MIB): At line 0 in (none)
hwDevMFanStatus.65536: Unknown Object Identifier (Sub-id not found: (top) -> hwDevMFanStatus)
/etc/snmp/snmpd.conf is identical for both servers and so is /etc/sysconfig/snmp.
set does not show any ENV variable related to snmp or mib.
Thanks
You are confusing snmpd.conf and snmp.conf the former being the configuration file for the SNMP daemon whereas Net-SNMP applications use snmp.conf.
The mibs/mibdirs directives you are interested in would be specified in snmp.conf (see also man snmp.conf.
Related
I'm trying to add a custom mib file that contains few nodes.
For an example I tried loading SNMP-COMMUNITY-MIB as it's a standard mib and thus shouldn't throw errors.
I copied the mib into the path
~/.snmp/mibs
and also updated snmpd.conf as:
mibdirs +$HOME/.snmp/mibs
mibs +SNMP-COMMUNITY-MIB
I tried to print the oid of one of the nodes "snmpCommunityName" using:
snmptranslate -m +SNMP-COMMUNITY-MIB -IR -On snmpCommunityName
it worked fine and the oid was printed.
I then tried to list all using snmpwalk:
snmpwalk -v2c -c public localhost
But the nodes from my mib and its oid's were not printed.
How can I have my oids listed on snmpwalk?
I accidentally noticed that when I run snmpwalk without an OID, I get only 593 variables from my device, and the device-specific variables are missing. But if I add 1 as the OID, I get 2527 variables, including the ones which are the most useful. So in your case try adding 1 at the end of the snmpwalk command:
snmpwalk -v2c -c public localhost 1
Edit: The above method worked on an APC PDU, and on a Supermicro BMC. The BMC was a bit confusing because it did not use the OID names from the MIB file, but all the information I need is there.
i try to monitor values with nagios over snmp from my two audiocodes SBCs (M500L).
For these i download two MIBs "AC-ALARM-MIB" + "IP-MIB_rfc4293" from https://github.com/librenms/librenms/tree/master/mibs/audiocodes rename it to .txt at the end and upload it to my ubuntu server in path /usr/share/snmp/mibs/.
Then i try to use the following command in command line.
snmpget -v3 -l authPriv -u xxxxxx -a SHA -A xxxxx -x AES -X xxxxx 123.456.789.100 AcAlarm:acActiveAlarmName
and i get the following output
AcAlarm::acActiveAlarmName = No Such Instance currently exists at this OID
I try to find out the OID from these in MIB Browser - seems like it is " .1.3.6.1.4.1.5003.11.1.1.1.1.5". When i use these OID i get same output.
Anyone has an idea?
SNMP treats all values as being entries in some database. OIDs are used to identify entries in this conceptual database. MIB files allow an SNMP manager to translate OIDs into a human-readable string, with an accompanying textual description.
The issue here is not that the MIB files are bad, or the OIDs are wrong, the problem is that, either the devices that hold this (imaginary) database do not support the entries you are trying to access, or that your user is not authorized to access those entries. A simple way to find out what OIDs are supported would be to do a full walk of the database, using something like snmpwalk <hostname> 1.3.6.1
Given the following sample/simple snmpd.conf (Net-SNMP 5.7.2 on RHEL 7.4)
rwcommunity private 192.168.56.101
trapsess -Ci --clientaddr=192.168.56.128 -v 2c -c private 192.168.56.101:162
when starting a SNMP Daemon
snmpd -f -Lo -D -C -c data/snmpd_test.conf udp:192.168.56.128:161
We obtain ''Start Up'' InformRequest with IP source 192.56.168.1 instead of ...128 (WireShark snapshot below)
It is not surprising as the -D option allows us to output the debug information saying that
trace: netsnmp_config_process_memory_list(): read_config.c, 696:
read_config:mem: processing memory: clientaddr 192.168.56.128
trace: run_config_handler(): read_config.c, 562:
9:read_config:parser: clientaddr handler not registered for this time
Web sources however say:
snmp.conf
...This value is also used by snmpd when generating notifications.
snmpd.conf
trapsess [SNMPCMD_ARGS] HOST
provides a more generic mechanism for defining notification destinations.
SNMPCMD_ARGS should be the command-line options required for an equivalent
snmptrap (or snmpinform) command to send the desired notification
I read also some old threads like this one
However this option is working well with snmptrap
snmptrap -D -Lo -Ci --clientaddr=192.168.56.128 -M+path_to_my_mibs -v 2c -c private 192.168.56.101:162 "" .1.3.6.1.4.1.a.b.c.d.e.f.0 i 0
This option is also working when placed in snmp.conf ( mind there is no 'd' here ) and then it applies to snmpset and snmpget (and maybe other)
So my question is: Is it a documentation error, a bug, a misuse of the Net-SNMP stack ?
After a long struggle I may have an answer and I write a short note as I just found a trick
It seems that clientaddr is not parsed correctly wherever in the snmpd.conf
(I tried not also inside the trapsess line)
But it seems to be a valid option in the command line of snmpd
like it was a valid option in the snmptrap command line. So I assumed it could be the same parsing mechanism for both.
a condition also is that the IP addres must be valid one
which means that
snmpd -f -Lo -D -C -c data/snmpd_test.conf --clientaddr=192.168.56.128 udp:192.168.56.128:161
seems to fully solve my problem.
I will perform more tests and if accurate format this answer a little bit better but it seems a good hint.
The problem
SNMPD is correctly delegating SNMP polling requests to another program but the response from that program is not valid. A manual run of the program with the same arguments is responding correctly.
The detail
I've installed the correct LSI raid drivers on a server and want to configure SNMP. As per the instructions, I've added the following to /etc/snmp/snmpd.conf to redirect SNMP polling requests with a given OID prefix to a program:
pass .1.3.6.1.4.1.3582 /usr/sbin/lsi_mrdsnmpmain
It doesn't work correctly for SNMP polling requests:
snmpget -v1 -c public localhost .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.1
I get the following response:
Error in packet
Reason: (noSuchName) There is no such variable name in this MIB.
Failed object: SNMPv2-SMI::enterprises.3582.5.1.4.2.1.2.1.32.1
What I've tried
SNMPD passes two arguments, -g and <oid> and expects a three line response <oid>, <data-type> and <data-value>.
If I manually run the following:
/usr/sbin/lsi_mrdsnmpmain -g .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.0
I correctly get a correct three line response:
.1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.0
integer
30
This means that the pass command is working correctly and the /usr/sbin/lsi_mrdsnmpmain program is working correctly in this example
I tried replacing /usr/sbin/lsi_mrdsnmpmain with a bash script. The bash script delegates the call and logs the supplied arguments and output from the delegated call:
#!/bin/bash
echo "In: '$#" > /var/log/snmp-pass-test
RETURN=$(/usr/sbin/lsi_mrdsnmpmain $#)
echo "$RETURN"
echo "Out: '$RETURN'" >> /var/log/snmp-pass-test
And modified the pass command to redirect to the bash script. If I run the bash script manually /usr/sbin/snmp-pass-test -g .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.0 I get the correct three line response as I did when I ran /usr/sbin/lsi_mrdsnmpmain manually and I get the following logged:
In: '-g .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.0
Out: '.1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.0
integer
30'
When I rerun the snmpget test, I get the same Error in packet... error and the bash script's logging shows that the captured delegated call output is empty:
In: '-g .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.0
Out: ''
If I modify the bash script to only echo an empty line I also get the same Error in packet... message.
I've also tried ensuring that the environment variables that are present when I manually call /usr/sbin/lsi_mrdsnmpmain are the same for the bash script but I get the same empty output.
Finally, my questions
Why would the bash script behave differently in these two scenarios?
Is it likely that the problem that exists with the bash scripts is the same as originally noticed (manually running program has different output to SNMPD run program)?
Updates
eewanco's suggestions
What user is running the program in each scenario?
I added echo "$(whoami)" > /var/log/snmp-pass-test to the bash script and root was added to the logs
Maybe try executing it in cron
Adding the following to root's crontab and the correct three line response was logged:
* * * * * /usr/sbin/lsi_mrdsnmpmain -g .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.1 >> /var/log/snmp-test-cron 2>&1
Grisha Levit's suggestion
Try logging the stderr
There aren't any errors logged
Checking /var/log/messages
When I run it via SNMPD, I get MegaRAID SNMP AGENT: Error in getting Shared Memory(lsi_mrdsnmpmain) logged. When I run it directly, I don't. I've done a bit of googling and I may need lm_sensors installed; I'll try this.
I installed lm_sensors & compat-libstdc++-33.i686 (the latter because it said it was a pre-requisite from the instructions and I was missing it), uninstalled and reinstalled the LSI drivers and am experiencing the same issue.
SELinux
I accidently stumbled upon a page about extending snmpd with scripts and it says to check the script has the right SELinux context. I ran grep AVC /var/log/audit/audit.log | grep snmp before and after running a snmpget and the following entry is added as a direct result from running snmpget:
type=AVC msg=audit(1485967641.075:271): avc: denied { unix_read unix_write } for pid=5552 comm="lsi_mrdsnmpmain" key=558265 scontext=system_u:system_r:snmpd_t:s0 tcontext=system_u:system_r:initrc_t:s0 tclass=shm
I'm now assuming that SELinux is causing the call to fail; I'll dig further...see answer for solution.
strace (eewanco's suggestion)
Try using strace with and without snmp and see if you can catch a system call failure or some additional hints
For completeness, I wanted to see if strace would have hinted that SELinux was denying. I had to remove the policy packages using semodule -r <policy-package-name> to reintroduce the problem then ran the following:
strace snmpget -v1 -c public localhost .1.3.6.1.4.1.3582.5.1.4.2.1.2.1.32.1 >> strace.log 2>&1
The end of strace.log is as follows and unless I'm missing something, it doesn't seem to provide any hints:
...
sendmsg(3, {msg_name(16)={sa_family=AF_INET, sin_port=htons(161), sin_addr=inet_addr("127.0.0.1")}, msg_iov(1)= [{"0;\2\1\0\4\20public\240$\2\4I\264-m\2"..., 61}], msg_controllen=32, {cmsg_len=28, cmsg_level=SOL_IP, cmsg_type=, ...}, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 61
select(4, [3], NULL, NULL, {0, 999997}) = 1 (in [3], left {0, 998475})
brk(0xab9000) = 0xab9000
recvmsg(3, {msg_name(16)={sa_family=AF_INET, sin_port=htons(161), sin_addr=inet_addr("127.0.0.1")}, msg_iov(1)= [{"0;\2\1\0\4\20public\242$\2\4I\264-m\2"..., 65536}], msg_controllen=0, msg_flags=0}, MSG_DONTWAIT) = 61
write(2, "Error in packet\nReason: (noSuchN"..., 81Error in packet
Reason: (noSuchName) There is no such variable name in this MIB.
) = 81
write(2, "Failed object: ", 15Failed object: ) = 15
write(2, "SNMPv2-SMI::enterprises.3582.5.1"..., 48SNMPv2- SMI::enterprises.3582.5.1.4.2.1.2.1.32.1
) = 48
write(2, "\n", 1
) = 1
brk(0xaa9000) = 0xaa9000
close(3) = 0
exit_group(2) = ?
+++ exited with 2 +++
It was SELinux that was denying snmpd a delegated call to /usr/sbin/lsi_mrdsnmpmain (and probably beyond).
To identify it, I ran grep AVC /var/log/audit/audit.log and for each entry, I ran the following:
echo "<grepped-output>" | audit2allow -a -M <filename>
This creates a SELinux policy package that should allow the delegated call through. The package is then loaded using the following:
semodule -i <filename>.pp
I had to do this 5 times as there were different causes of denial (unix_read unix_write, associate, read write). I'll look to combine the modules into one.
Now when I run snmpget I get the correct delegated output:
SNMPv2-SMI::enterprises.3582.5.1.4.2.1.2.1.32.1 = INTEGER: 34
I'm trying to load the snmpv2 mibs and net-snmp can't find them.
I use the -M [folder] option to tell snmpget where to find the custom mibs.
snmpget -v 2c -c public -M /home/myprofile/mibs 192.168.1.55 RFC1213-MIB::sysDescr
I get the error,
Cannot find module (SNMPv2-SMI): at line 0 in (none)
RFC1213-MIB::sysDescr: Unknown Object Identifier
What am I missing given these are standard mibs?
When you use -M to specify a folder, you have to make that folder contains all necessary MIB documents (not only yours, but all dependencies as well). Otherwise, Net-SNMP cannot find them (by design), which you can read Net-SNMP man page for more details,
http://www.net-snmp.org/docs/man/snmpcmd.html
Thus, the easiest way is to use
snmpget -v 2c -c public -M +/home/myprofile/mibs 192.168.1.55 RFC1213-MIB::sysDescr