You can download custom MIB files for most popular vendors (Cisco, Juniper, …) that allow you to talk SNMP to their device. In most cases, your commands will end up like this.
snmpwalk -v 2c -c community -m JUNIPER-COS-MIB 192.168.1.1
In the snmp-commands, you specify which MIB to load. If you’re using the same MIBS over and over again, this gets … annoying. So, add a MIB auto loader in the SNMP client configuration so it’s there for you to use every time.
First, check where the SNMP client config loads its configuration file from.
# net-snmp-config --snmpconfpath /etc/snmp:/usr/share/snmp:/usr/lib/snmp:/root/.snmp:/var/net-snmp
In that case, the /etc/snmp is included (this’ll be the case for nearly every snmp config). So, create a new file called /etc/snmp/snmp.conf (note: there may already be an snmpd.conf, that’s a different config!) and give it the following input.
mibs +JUNIPER-COS-MIB
If there’s already data in the snmp.conf, just add it at the bottom. You can simply insert new lines with extra MIBs to auto-load when using SNMP client commands.