Hi net-snmp-coders,

I've been working on updating the net-snmp version of software we use on Centos 
7 to net-snmp 5.9.  This is being required because of a vulnerability that is 
know in the NIST vulnerability database. We develop our own MIB groups in C and 
compile them in to source code repos that we pull for the site.  Everything has 
worked great for -v2c. We are now trying to get this implemented for -v3 and 
running into major issues.  I believe this is a configuration issues because 
running the following command on "net-snmp-config --create-snmpv3-user -a MD5 
-A myuser12345 myuser"  from this 
guide<https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.thegeekdiary.com%2Fcentos-rhel-6-install-and-configure-snmpv3%2F&data=04%7C01%7Cjcook%40envistacom.com%7C38ac1d1419234f50efe508d8c6c52549%7C8d7424e25e1b48f699abe818cd9f5507%7C1%7C0%7C637477897349851608%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=fH18R0pTYx5XrXTYoeCPOEdGF6brGEwSk5I0JGTprew%3D&reserved=0>.
 This creates everything here.


[root@localhost]# net-snmp-config --create-snmpv3-user -a MD5 -A my_password 
myuser
adding the following line to /var/net-snmp/snmpd.conf:
   createUser myuser MD5 "my_password" DES ""
adding the following line to /snmp/snmpd.conf:
   rwuser myuser

This appears to be where the issue happen.  When I start our compiled snmpd 
binary it seems to overwrite /var/net-snmp/snmpd.conf every time.  Therefore I 
can never create our initial snmpv3 users and every time I run a snmpwalk I get.

[evcLinuxAdmin@localhost ~]$ snmpwalk -v3 -u myuser -l authNoPriv -a MD5 -A my_ 
password localhost
snmpwalk: Unknown user name

I've stepped back and stripped all our C mib-group code from the build to keep 
it all repo only code. I did this to ensure it's not us.  Running into the same 
issue there I dropped back to run on the yum installed net-snmp version that is 
know to our yum repo created the user again following the guide from above.

[user@localhost ~]$ /usr/sbin/snmpd --version

NET-SNMP version:  5.7.2
Web:               http://www.net-snmp.org/
Email:             
net-snmp-coders@lists.sourceforge.net<mailto:net-snmp-coders@lists.sourceforge.net>

[root]# net-snmp-config --create-snmpv3-user -a MD5 -A my_password myuser
adding the following line to /var/net-snmp/snmpd.conf:
   createUser myuser MD5 "my_password" DES ""
adding the following line to /snmp/snmpd.conf:
   rwuser myuser

Then I started the snmp service

[---@localhost ~]$ service snmpd start
Redirecting to /bin/systemctl start snmpd.service
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to manage system services or units.
Authenticating as:
Password:
==== AUTHENTICATION COMPLETE ===
[---@localhost ~]$


Now that the system is running my snmpwalk command works for -v3

        snmpwalk -v3 -u myuser -l authNoPriv -a MD5 -A my_password localhost

I was also able to use the snmpusm command to create additional users. When 
using this on the 5.9 repo all I get is user not found.

Jumping back to the 5.9 binary build I know the following

sudo snmpd -Dread_config -H 2>&1 | grep Read | sort -u
[sudo] password for evcLinuxAdmin:
read_config:file: Reading configuration /etc/snmp/snmpd.conf (0)
read_config:file: Reading configuration /etc/snmp/snmpd.conf (1)   ------->  
This file has my rwuser myuser
read_config:file: Reading configuration /var/lib/net-snmp/snmpd.conf (0)
read_config:file: Reading configuration /var/lib/net-snmp/snmpd.conf (1) -> I 
manually added the create user info to this file for myuser and it doesn't seem 
to be picking it up.

[evcLinuxAdmin@localhost ~]$ snmpd -Dread_config -H 2>&1 | grep config:path | 
sort -u
read_config:path:  config path used for 
agentx:/usr/local/etc/snmp:/usr/local/share/snmp:/usr/local/lib/snmp:/home/evcLinuxAdmin/.snmp
 (persistent path:/var/net-snmp)
read_config:path:  config path used for agentx:/var/net-snmp (persistent 
path:/var/net-snmp)  --> This is where everything was originally created but 
deleted when snmpd starts.
read_config:path:  config path used for 
snmpd:/usr/local/etc/snmp:/usr/local/share/snmp:/usr/local/lib/snmp:/home/evcLinuxAdmin/.snmp
 (persistent path:/var/net-snmp)
read_config:path:  config path used for snmpd:/var/net-snmp (persistent 
path:/var/net-snmp)
read_config:path:  config path used for 
snmp:/usr/local/etc/snmp:/usr/local/share/snmp:/usr/local/lib/snmp:/home/evcLinuxAdmin/.snmp
 (persistent path:/var/net-snmp)
read_config:path:  config path used for snmp:/var/net-snmp (persistent 
path:/var/net-snmp)

At this point I think it's a configuration parameter but I don't see anything 
that would effect or cause this behavior.  I didn't see anything in the change 
log to suggest 5.9 was changed from 5.7.  Any help you can provide would be 
helpful as this is needed to meet a customer deliverable.  Perhaps there is a 
clear document out there because I have been all over the net-snmp provided 
documents and nothing was found to solve my problem.

Thanks
Justin


Justin Cook
Software Technical Engineering Manager

[cid:image001.png@01D6F884.FA255350]

Envistacom, LLC
C: 301.712.5481
jc...@envistacom.com<mailto:jc...@envistacom.com>
www.envistacom.com<https://www.envistacom.com/>

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