School server network debugging
From OLPC
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When debugging a School server connectivity issue, there are a number of tools to use. These require an ssh connection (or console access) to the school server.
- A useful discussion for LAN/WAN debugging, http://lists.laptop.org/pipermail/server-devel/2010-July/004995.html
[edit] Are the Interfaces Present
First, check to see what the schoolserver OS thinks it's network interfaces are:
[edit] ifconfig
You can check on the interfaces using the ifconfig command:
/sbin/ifconfig /sbin/ifconfig eth0
A typical ifconfig output (for a machine with two Active Antenna and one wired network interface) is:
br0 Link encap:Ethernet HWaddr 00:50:43:28:0A:B7
inet addr:172.18.16.1 Bcast:172.18.31.255 Mask:255.255.240.0
inet6 addr: fe80:0:0:10::1/64 Scope:Link
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:64 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:12653 (12.3 KiB)
br1 Link encap:Ethernet HWaddr 00:50:43:28:0A:B8
inet addr:172.18.32.1 Bcast:172.18.47.255 Mask:255.255.240.0
inet6 addr: fe80:0:0:11::1/64 Scope:Link
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:12 errors:0 dropped:0 overruns:0 frame:0
TX packets:75 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:2352 (2.2 KiB) TX bytes:15080 (14.7 KiB)
br2 Link encap:Ethernet HWaddr 00:00:00:00:00:00
inet addr:172.18.48.1 Bcast:172.18.63.255 Mask:255.255.240.0
inet6 addr: fe80:0:0:12::1/64 Scope:Link
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:66 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:0 (0.0 b) TX bytes:12911 (12.6 KiB)
eth0 Link encap:Ethernet HWaddr 00:19:5B:68:9D:4E
inet addr:172.16.0.53 Bcast:172.16.0.255 Mask:255.255.255.0
inet6 addr: fe80::219:5bff:fe68:9d4e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:283 errors:0 dropped:0 overruns:0 frame:0
TX packets:234 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:31477 (30.7 KiB) TX bytes:31716 (30.9 KiB)
Interrupt:17 Base address:0x2000
eth1 Link encap:Ethernet HWaddr 00:40:63:E9:99:9B
inet addr:172.18.0.1 Bcast:172.18.15.255 Mask:255.255.240.0
inet6 addr: fe80::1/64 Scope:Link
inet6 addr: fe80::240:63ff:fee9:999b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:76 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 b) TX bytes:13857 (13.5 KiB)
Interrupt:18 Base address:0xf800
eth2 Link encap:Ethernet HWaddr 00:50:43:28:0A:B7
inet6 addr: fe80::250:43ff:fe28:ab7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:36 errors:0 dropped:0 overruns:0 frame:0
TX packets:1118 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:8591 (8.3 KiB) TX bytes:130628 (127.5 KiB)
eth3 Link encap:Ethernet HWaddr 00:50:43:28:0A:B8
inet6 addr: fe80::250:43ff:fe28:ab8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:29 errors:0 dropped:0 overruns:0 frame:0
TX packets:330 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:5429 (5.3 KiB) TX bytes:58058 (56.6 KiB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1 errors:0 dropped:0 overruns:0 frame:0
TX packets:1 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:76 (76.0 b) TX bytes:76 (76.0 b)
msh0 Link encap:Ethernet HWaddr 00:50:43:28:0A:B7
inet6 addr: fe80::250:43ff:fe28:ab7/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:36 errors:0 dropped:0 overruns:0 frame:0
TX packets:1118 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:8591 (8.3 KiB) TX bytes:130628 (127.5 KiB)
msh1 Link encap:Ethernet HWaddr 00:50:43:28:0A:B8
inet6 addr: fe80::250:43ff:fe28:ab8/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:29 errors:0 dropped:0 overruns:0 frame:0
TX packets:330 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:5429 (5.3 KiB) TX bytes:58058 (56.6 KiB)
[edit] iwconfig
The details of the wireless interfaces can be seen using iwconfig :
/sbin/iwconfig /sbin/iwconfig msh0
A typical output for this command (when using two Active Antenna) is:
lo no wireless extensions.
eth1 no wireless extensions.
eth0 no wireless extensions.
br0 no wireless extensions.
br1 no wireless extensions.
br2 no wireless extensions.
eth2 IEEE 802.11b/g ESSID:"school-mesh-0" Nickname:"schoolserver"
Mode:Ad-Hoc Frequency:2.412 GHz Cell: 00:33:33:FF:28:0A
Bit Rate:2 Mb/s Tx-Power=13 dBm
Retry limit:8 RTS thr=2347 B Fragment thr=2346 B
Power Management:off
Link Quality=100/100 Signal level=-256 dBm Noise level=-96 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:3932
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
msh0 IEEE 802.11b/g ESSID:"mesh" Nickname:"Mesh"
Mode:Repeater Frequency:2.412 GHz Bit Rate:2 Mb/s Tx-Power=13 dBm
Retry limit:8 RTS thr=2347 B Fragment thr=2346 B
Power Management:off
Link Quality=100/100 Signal level=-256 dBm Noise level=-96 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:3936
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
eth3 IEEE 802.11b/g ESSID:"school-mesh-1" Nickname:"schoolserver"
Mode:Ad-Hoc Frequency:2.462 GHz Cell: 00:02:00:2A:09:00
Bit Rate:2 Mb/s Tx-Power=13 dBm
Retry limit:8 RTS thr=2347 B Fragment thr=2346 B
Power Management:off
Link Quality=100/100 Signal level=-256 dBm Noise level=-96 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:2698
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
msh1 IEEE 802.11b/g ESSID:"mesh" Nickname:"Mesh"
Mode:Repeater Frequency:2.462 GHz Bit Rate:2 Mb/s Tx-Power=13 dBm
Retry limit:8 RTS thr=2347 B Fragment thr=2346 B
Power Management:off
Link Quality=100/100 Signal level=-256 dBm Noise level=-96 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:2703
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
[edit] route
Discuss the use of the route command in debugging...
[edit] Are Basic Services Running
You can check on the status of the basic services (DHCP, DNS) using:
sudo service dhcpd status sudo service named status
[edit] DHCP
If there are laptop running on the mesh, there will be DHCP traffic associated with each one every five minutes. This may be watched using:
sudo tail -f /var/log/messages
[edit] DNS
host and dig
[edit] Watching the Packets Go By
You can take a look at the packets traveling over an interface (in this case school-mesh-0) using the tcpdump command:
/sbin/tcpdump -i msh0
[edit] Turning On Additional Wireless Mesh Debugging
You can find out specific about the wireless mesh software drivers being used by using ethtool:
/sbin/ethtool -i msh0
You can enable additional debugging output from the driver using:
echo 0x136184 > /sys/module/libertas/parameters/libertas_debug
