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More on Networking

This document help to undersand basic Network Configuration for a machine and general networking.


ifconfig - IP address

To check your own IP address.

ifconfig

In the example below: * LAN Ethernet IP is: 192.168.0.11 * Mac Address is: 00:16:35:69:BD:79

Example Output:

$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:16:35:69:BD:79
        inet addr:192.168.0.11  Bcast:192.168.0.255  Mask:255.255.255.0
        inet6 addr: fe80::212:ff35:fe69:bd12/64 Scope:Link
        UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
        RX packets:16791460 errors:0 dropped:0 overruns:0 frame:0
        TX packets:30066639 errors:0 dropped:0 overruns:0 carrier:0
        collisions:0 txqueuelen:1000
        RX bytes:2182259898 (2.0 GiB)  TX bytes:3951206845 (3.6 GiB)
        Interrupt:209 Memory:fdef0000-fdf00000

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:32098 errors:0 dropped:0 overruns:0 frame:0
        TX packets:32098 errors:0 dropped:0 overruns:0 carrier:0
        collisions:0 txqueuelen:0
        RX bytes:3227365 (3.0 MiB)  TX bytes:3227365 (3.0 MiB)

ping - Check network Access

ping [HOST or IP-ADDRESS or WEBSITE]

netstat - Network Activity

netstat -r

Example Output:

$ netstat -r
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
192.168.0.0     *               255.255.255.0   U         0 0          0 eth0
169.254.0.0     *               255.255.0.0     U         0 0          0 eth0
10.1.0.0    192.168.0.2 255.255.0.0     U         0 0          0 eth0
default         192.168.0.1     0.0.0.0         UG        0 0          0 eth0

Other usage

$ netstat -a | grep LISTEN | grep -v LISTENING
tcp        0      0 localhost.localdomain:32000 *:*                 LISTEN
tcp        0      0 localhost.locald:bootserver *:*                 LISTEN
tcp        0      0 *:cbt                       *:*                 LISTEN
tcp        0      0 *:38821                     *:*                 LISTEN
tcp        0      0 *:8009                      *:*                 LISTEN

$ netstat -an | more
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address             Foreign Address         State
tcp        0      0 127.0.0.1:32000           0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:2016            0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:7777              0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:38821             0.0.0.0:*               LISTEN

traceroute - Trace server routes to remote host

This command will display the route taken to reach the remote host and, along with the stops it makes, provide some timing information that shows how long each leg in the route is taking.

traceroute [HOSTNAME or SERVER or WEBSITE]

Example output:

$ traceroute www.google.com
traceroute to www.google.com (216.58.219.4), 30 hops max, 60 byte packets
1  testwifi.here (192.168.86.1)  0.588 ms  1.110 ms  0.725 ms
2  96.120.88.245 (96.120.88.245)  9.233 ms  14.729 ms  15.564 ms
3  be-20002-rur02.santaclara.ca.sfba.comcast.net (68.85.103.169)  16.102 ms  16.221 ms  15.741 ms
4  162.151.78.129 (162.151.78.129)  15.626 ms  15.836 ms  15.772 ms
5  be-232-rar01.santaclara.ca.sfba.comcast.net (162.151.78.253)  16.099 ms * *
6  be-299-ar01.santaclara.ca.sfba.comcast.net (68.86.143.93)  15.896 ms  13.372 ms  13.345 ms
7  96.112.146.18 (96.112.146.18)  13.998 ms 96.112.146.26 (96.112.146.26)  11.898 ms  11.132 ms
8  * * *
9  108.170.236.62 (108.170.236.62)  19.286 ms 209.85.251.4 (209.85.251.4)  17.231 ms 108.170.236.60 (108.170.236.60)  16.081 ms
10  108.170.242.254 (108.170.242.254)  18.317 ms 108.170.242.238 (108.170.242.238)  17.908 ms 108.170.242.253 (108.170.242.253)  17.933 ms
11  216.239.62.41 (216.239.62.41)  18.089 ms 72.14.237.147 (72.14.237.147)  18.223 ms 66.249.94.29 (66.249.94.29)  18.394 ms
12  66.249.95.15 (66.249.95.15)  23.803 ms 216.239.54.22 (216.239.54.22)  21.822 ms 64.233.174.206 (64.233.174.206)  36.001 ms
13  108.170.234.40 (108.170.234.40)  22.110 ms 108.170.230.134 (108.170.230.134)  22.006 ms  21.297 ms
14  108.170.247.193 (108.170.247.193)  22.033 ms  21.847 ms 108.170.247.225 (108.170.247.225)  19.486 ms
15  108.170.237.143 (108.170.237.143)  20.839 ms  19.894 ms  17.991 ms
16  lax17s03-in-f4.1e100.net (216.58.219.4)  17.176 ms  17.725 ms  24.966 ms