Difference between revisions of "TroubleShooting network"
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| − | + | This article describes what you can do if you have network problems. We will first identify the problem and then solve it. | |
| + | |||
| + | = Do you have an IP address = | ||
| + | Find out if you have an IP address | ||
| + | ip addr | ||
| + | If you do not have an IP address, fix this problem before proceeding. | ||
| + | |||
| + | We assume your IP address is 192.168.0.2 | ||
| + | |||
| + | = Can you reach your computer = | ||
| + | Find out if you can reach your own computer | ||
| + | ping 192.168.0.2 | ||
| + | |||
| + | = Do you have a standard gateway = | ||
| + | If you can ping all computers in your network but not any computer in the internet you probably don't have a gateway configured. Find out with the [[command]] [[route]] like this: | ||
| + | # route | ||
| + | Kernel IP routing table | ||
| + | Destination Gateway Genmask Flags Metric Ref Use Iface | ||
| + | <font color=blue>192.168.0.0 * 255.255.255.0 U 0 0 0 eth1</font> | ||
| + | link-local * 255.255.0.0 U 0 0 0 eth1 | ||
| + | loopback * 255.0.0.0 U 0 0 0 lo | ||
| + | <font color=blue>default 192.168.0.1 0.0.0.0 UG 0 0 0 eth1</font> | ||
| + | The first blue line means: If there is any IP package for an IP address 192.168.0.*, just send it over network device ''eth1''. The second blue line means: Every IP package that has not been handled yet, send over network device ''eth1'' to the default gateway 192.168.0.1. | ||
| + | |||
| + | = See also = | ||
| + | * [[TroubleShooting]] | ||
| + | * [[NetWork]] | ||
| + | * [[TroubleShooting Sound]] | ||
| + | * [[iptraf]] | ||
| + | * [[ethtool]] | ||
| + | * [[nmap]] | ||
| + | * [[telnet]] | ||
| + | * [[netstat]] | ||
Latest revision as of 09:01, 11 January 2014
This article describes what you can do if you have network problems. We will first identify the problem and then solve it.
Contents
Do you have an IP address
Find out if you have an IP address
ip addr
If you do not have an IP address, fix this problem before proceeding.
We assume your IP address is 192.168.0.2
Can you reach your computer
Find out if you can reach your own computer
ping 192.168.0.2
Do you have a standard gateway
If you can ping all computers in your network but not any computer in the internet you probably don't have a gateway configured. Find out with the command route like this:
# route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.0.0 * 255.255.255.0 U 0 0 0 eth1 link-local * 255.255.0.0 U 0 0 0 eth1 loopback * 255.0.0.0 U 0 0 0 lo default 192.168.0.1 0.0.0.0 UG 0 0 0 eth1
The first blue line means: If there is any IP package for an IP address 192.168.0.*, just send it over network device eth1. The second blue line means: Every IP package that has not been handled yet, send over network device eth1 to the default gateway 192.168.0.1.
