Bob's Network Configuration

Network configuration

Bob (hostname bob) has the following network interfaces:

• eth0 connects to the internal bob network [192.168.0.*], statically assigned IP 192.168.0.100
• eth1 is unused, but can be connected to the robotics lab wired network for maintenance. Dynamic IP.
• wlan0 is connected to what ever wireless network is in use, usually ccarobot.

The additional onboard PC (hostname bobl) has a single wired network connection eth0 to the internal bob network. Network manager is removed and setup is in /etc/network/interfaces.

Internal "bob network"

The bob network [192.168.0.*] is supplied with an outside connection by NAT through bob. bob is the main machine on this network providing routing to other networks and DNS services. bobl is able to access any machine accessible from bob over the wlan0 interface by default. However, to access bobl from a machine that has access to bob (woody for example) you need to fist add bob as a route in the machines table:

sudo route add -net 192.168.0.0/24 dev eth0 gw bob

Hostnames and IP addresses

To enable ROS communication between your machine and bob network hosts, add an entry in /etc/hosts on bob and then update the internal network dns server:

sudo /etc/init.d/dnsmasq restart

Then both bobl and bob will be able to find your IP, editing /etc/hosts on bobl is not required. You might also want to add bob as an addition DNS server on your machine so that you do not have to maintain your own hosts file.

Time

The time on bob and bobl are synchronised using chrony. bob is the master, and can be used by offboard machines to synchonise with:

sudo ntpdate bob

ROS communication

bobl looks to bob for the ros core. On any off board machine, set the ROS_MASTER_URI to bob and make sure you add your hostname as above. In order to have full access to topics published by bobl you must first set the route as above.

Ping of life

Fixed machines sometimes loose communication with bob due to some unknown problem with the ccarobot network routers. This has always been fixable by pinging the lost machine from Bob, which then allows the machine to ping/ssh/etc Bob. As a work-around and to avoid regular manual pinging, the script /usr/bin/ping-hosts can be used to ping all hosts in Bob's hosts file. This is also ran automatically every 2 minutes, logging to /var/log/ping-hosts.

strands@bob:~$ cat /var/log/ping-hosts
----------------------------------------------------------------------
Wed, 14 Jan 2015 11:14:01 +0000
localhost                    live
bob                          live
bobl                         live
bobr                         down
cca-1128                     live
heatwave                     live
woody                        live

Configuration files

• The NAT is setup on bob in the file /etc/robotnet.sh, which is invoked by /etc/rc.local. robotnet script: https://gist.github.com/cburbridge/3ee13fb45a4f05ea7e1e
• The DNS services are provided using dnsmasq, configured in /etc/dnsmasq.conf: https://gist.github.com/cburbridge/56c1a4d94bfb48c1be46. The user of dns-maq by network manager needs to be removed by commenting out in /etc/NetworkManager/NetworkManager.conf.
• The network on bob is configured in Network Manager.
• The network connection on bobl is configured in /etc/network/interfaces: https://gist.github.com/cburbridge/2b7bc5e104ac95848501
• The chrony configuration is in /etc/chrony/chrony.conf. bobl gets from bob, bob from timehost.cs.bham.ac.uk when available. Bob configuration: https://gist.github.com/cburbridge/27502dc2ad7f74f0b48e; Bob-L configuration: https://gist.github.com/cburbridge/12eccdeb3dc2bdb63eb2
• ping-hosts script: https://gist.github.com/cburbridge/b185c60efc5efbc83bc5