School server network debugging
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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
Are the Interfaces Present
First, check to see what the schoolserver OS thinks it's network interfaces are:
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)
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
route
Discuss the use of the route command in debugging...
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
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
DNS
host and dig
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
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