Network troubleshoting

If after the Network configuration is still not possible to connect to the Internet you've to collect the following info before make a  [bug request].

To execute the following commands you've to open a terminal window and login with the superuser account.

Warning: the encryption key of a wireless net, the IP address, or other related info are sensible data that is better to hyde in the  report with the output of the following commands.

Wireless network diagnostic
Is possible to check the status of the wireless interfaces with:

iwconfig

An example output is:

wlan0    IEEE 802.11g  ESSID:"MyWiFi"  Nickname:"" Mode:Managed Frequency:2.457 GHz  Access Point: 00:A0:C1:F9:32:11 Bit Rate:24 Mb/s  Tx-Power:17 dBm   Sensitivity=1/1 Retry:off  RTS thr:off   Fragment thr:off Encryption key:4445-4647-4849-5051-5253-54  Security mode:restricted Power Management:off Link Quality=46/70 Signal level=-49 dBm  Noise level=-95 dBm Rx invalid nwid:0 Rx invalid crypt:0  Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0   Missed beacon:0

Where the dove link quality (Link Quality=46/70) and the hardware address of the Access Point (00:A0:C1:F9:32:11) shows that the association has been done.

Note: in that case the wireless interface is called wlan0, but in your case it can be called with a different name like wifi0 or ath0.

If the association has been done continue with the general diagnostic of the network interfaces ifconfig.

general diagnostic of the network interfaces ifconfig
To discover the status of all the network interfaces available execute the command:

ifconfig -a

Search the interface corresponding to the connection you're testing as for the following scheme:


 * ethernet interfaces: eth0, eth1, ...
 * wireless interfaces: wlan0, wifi0, ath0, ...
 * point-point interfaces (Dial-up, PPPoE o PPPoA): ppp0

an found, if available, the IP address (inet addr). For example the following output:

wlan0    Link encap:Ethernet  HWaddr 00:24:FA:BC:11:0A inet addr:192.168.1.3 Bcast:192.168.1.255  Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500  Metric:1 RX packets:34146 errors:0 dropped:0 overruns:0 frame:0 TX packets:16290 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:21670258 (20.6 Mb) TX bytes:1802529 (1.7 Mb)

shows that the wireless interface wlan0 has the IP address 192.168.1.3 and that the computer is available in the local network, so is possible to continue with the router diagnostic.

Note: the IP addresses that start with 10., 172., 192.168. and some other, are private addresses that require a NAT (Network Address Translation) on the Internet router.

Routing diagnostic
To make possible a Internet connection, a default gateway has to be setted. The default gateway shall be the ADSL router, or another network device put between the network access and the internet provider.

To discover the default gateway use the command:

route -n

the following output:

192.168.1.0    0.0.0.0         255.255.255.0   U     0      0        0 wlan0 0.0.0.0        192.168.1.1     0.0.0.0         UG    0      0        0 wlan0

shows that the device has the IP address 192.168.1.1 and tha is setted has default gateway. You can check the reachablity with:

ping 192.168.1.1

that in a correct working network shall report a result like this:

PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data. 64 bytes from 192.168.1.1: icmp_seq=1 ttl=255 time=1.93 ms 64 bytes from 192.168.1.1: icmp_seq=2 ttl=255 time=1.92 ms 64 bytes from 192.168.1.1: icmp_seq=3 ttl=255 time=2.00 ms 64 bytes from 192.168.1.1: icmp_seq=4 ttl=255 time=2.38 ms

Note: press CTRL-C to stop the execution of the ping.

if the ping has worked continue with the DNS diagnostic.

DNS Diagnostic
The DNS (Domain Name Server) is a vital component for the internet access, because is the responsible of translating the site names in the correct internet IP addresses (you can consider it like the yellowpages of internet).

The DNS configuration is in the file:

/etc/resolv.conf

you can show the contents of the file with:

cat /etc/resolv.conf

for example to connect over a Fastweb network you shall have a configuration like this:

search fastwebnet.it nameserver 213.156.56.80 nameserver 1.253.128.37
 * generated by /sbin/dhclient-script

In that case is advised too of use the ping command to verify the reachablity of the DNS:

[root@openmamba silvan]# ping 213.156.56.80 PING 213.156.56.80 (213.156.56.80) 56(84) bytes of data. 64 bytes from 213.156.56.80: icmp_seq=1 ttl=59 time=4.73 ms 64 bytes from 213.156.56.80: icmp_seq=2 ttl=59 time=4.68 ms

If even that test has worked is possible that we can ping an internet site, for example:

[root@openmamba silvan]# ping www.openmamba.org PING topix.openmamba.org (194.116.82.32) 56(84) bytes of data. 64 bytes from topix (194.116.82.32): icmp_seq=1 ttl=56 time=11.6 ms 64 bytes from topix (194.116.82.32): icmp_seq=2 ttl=56 time=12.3 ms

[root@openmamba silvan]# ping www.google.it PING www.l.google.com (209.85.129.147) 56(84) bytes of data. 64 bytes from fk-in-f147.google.com (209.85.129.147): icmp_seq=1 ttl=243 time=24.9 ms 64 bytes from fk-in-f147.google.com (209.85.129.147): icmp_seq=2 ttl=243 time=23.1 ms

Segnalazione di un problema
If you've completed successufully the diagnostic, but you are still not be able to connect to internt with konqueror, firefox or you are not able to make a system update send a  bug request with the output of the command showed in that page.