Netdot "Device"
- Represents a piece of infrastructure which you manage via SNMP
- e.g. switch, router, AP, server
- Can add individual devices manually via the GUI (SNMP or not)
- Add SNMP devices via command line
updatedevices.pl -H 10.10.0.254 -I -c NetManage
- Can sweep a subnet for SNMP devices
updatedevices.pl -B 10.10.0.0/24 -I -c NetManage- Warning: everyone will see your community string!
- And you might want to use the loopback address anyway
- Or add a list of devices from a text file (see manual)
Naming of devices
- Each device must have a primary IP and name
- Several sources, in configurable order, e.g.
- resolve SNMP sysName
- reverse DNS of the snmp target
- Unfortunately doesn't work well unless your DNS is already working
- Not good if you are planning to use Netdot to fix your DNS!
- The device name is a key in Netdot's DNS tables, but may not be associated with an A record (RR)
- Device serial numbers are checked, but you only get a warning if they overlap
- Sometimes we see the same serial number more than once, e.g. with emulated hardware (dynamips) or faulty equipment
End user PCs are not "Devices"
- They are auto-detected from ARP tables and forwarding tables
- You can search for them by IP or MAC address
- You can see which switch port they were last plugged into
- You can see when the IP was last active
Polling of devices
- A cron job polls your devices periodically (say) every hour
- Don't forget to
cp netdot.cron /etc/cron.d/netdot
updatedevices.pl -DIFAT
- Poll only devices in databases
- Refresh basic information (sysName, sysLocation etc)
- Read forwarding tables from switches
- Read ARP tables from routers
- Read CDP/LLDP topology
"Address" (a.k.a. "ipblock")
- Represents a single IP, or a prefix
- Prefix can be "container" or "subnet"
- A "subnet" is something actually seen on a router interface
- A "container" can contain subnets or other containers (recursively)
- A "subnet" cannot contain subnets or containers
- A "container" will be turned into a "subnet" if it's seen on a router interface
- Single IPs have different states
- Static - belongs to a device interface, or manually set to static
- Discovered - seen in ARP table
- Dynamic - defined as part of a DHCP pool
- Reserved - should not be assigned
VLANS
- Discovered from switches/routers
- Right now, a dot1q tag must be unique across your network
DNS
- Must create a DNS zone first, then the records
- Create reverse DNS zones, or you won't get PTR records created
- Netdot can create unique DNS names for each device interface, based on e.g. interface type and number
- This is configurable, and you can write a module for your own naming convention if you wish
DHCP
- Can create config files for ISC DHCP server, e.g. to give static IPs to particular hosts
- Create a DHCP "scope"
- Then you mark a row individual IPs as "dynamic", using the bulk update facility
- So that the DHCP range doesn't have to fall on subnet boundary
- Probably won't scale to v6 :-)
Not convered in this presentation
- Cable plant
- Contacts and People
- Reports
- Exporting
Documentation
- Finding stuff can be difficult
- "I know that Netdot can show my network topology, but where was it again?"
- It's open source, you can contribute to the documentation
- apache + mod_perl
- mysql
- rrdtool
- graphviz
- ...lots of perl dependencies