Monday, April 23, 2012

Linux Find Out My IP Number ( IP Address )

How do I find out ip number (IP Address) of my Linux server using command line options?

You can use any one of the following command to find out your IP address, routing table, devices, tunnels, and much more.
[a] ip command : Display or configure ip network information.
[b] ifconfig command : Display or configure ip network information.

ip Command Example

To display ip address, enter:
$ ip addr show
Sample outputs:
1: lo:  mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0: mtu 1500 qdisc mq state DOWN qlen 1000
link/ether b8:ac:6f:65:31:e5 brd ff:ff:ff:ff:ff:ff
3: wlan0: mtu 1500 qdisc mq state UP qlen 1000
link/ether 00:21:6a:bf:2d:64 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.100/24 brd 192.168.1.255 scope global wlan0
inet6 fe80::221:6aff:febf:2d64/64 scope link
valid_lft forever preferred_lft forever
4: virbr0: mtu 1500 qdisc noqueue state UNKNOWN
link/ether c2:86:1d:f6:17:a1 brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
inet6 fe80::c086:1dff:fef6:17a1/64 scope link
valid_lft forever preferred_lft forever
6: pan0: mtu 1500 qdisc noop state DOWN
link/ether fe:84:69:82:05:fb brd ff:ff:ff:ff:ff:ff
8: ppp0: mtu 1496 qdisc pfifo_fast state UNKNOWN qlen 3
link/ppp
inet 10.1.3.180 peer 10.0.31.18/32 scope global ppp0
To see eth0 or wlan0 interface ip info, enter:
$ ip addr show eth0
OR
$ ip addr show wlan0
To see current routing table, enter:
$ ip route show
Sample outputs:
10.0.31.18 dev ppp0  proto kernel  scope link  src 10.1.3.180
38.96.196.94 via 192.168.1.2 dev wlan0 src 192.168.1.100
192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.100 metric 2
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1
169.254.0.0/16 dev wlan0 scope link metric 1000
10.0.0.0/8 dev ppp0 scope link
default via 192.168.1.2 dev wlan0 proto static
To see your dns address, enter:
$ cat /etc/resolv.conf
Sample outputs:
domain nixcraft.net.in
search nixcraft.net.in
nameserver 127.0.0.1
nameserver 192.168.1.2
nameserver 10.1.2.30
To see network stats, enter:
$ netstat -i
Sample outputs:
Iface   MTU Met   RX-OK RX-ERR RX-DRP RX-OVR    TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 0 0 0 0 0 0 0 0 0 BMU
lo 16436 0 34 0 0 0 34 0 0 0 LRU
ppp0 1496 0 1734 0 0 0 2348 0 0 0 MOPRU
virbr0 1500 0 0 0 0 0 6 0 0 0 BMRU
wlan0 1500 0 2663556 0 0 0 2393688 0 0 0 BMRU
To see detailed stats, enter:
$ netstat -s
Ip:
2665087 total packets received
0 forwarded
0 incoming packets discarded
2664956 incoming packets delivered
2395808 requests sent out
5 dropped because of missing route
189 reassemblies required
91 packets reassembled ok
Icmp:
84 ICMP messages received
28 input ICMP message failed.
ICMP input histogram:
destination unreachable: 22
timeout in transit: 60
echo replies: 2
375 ICMP messages sent
0 ICMP messages failed
ICMP output histogram:
destination unreachable: 371
echo request: 4
IcmpMsg:
InType0: 2
InType3: 22
InType11: 60
OutType3: 371
OutType8: 4
Tcp:
20610 active connections openings
31585 passive connection openings
8024 failed connection attempts
1251 connection resets received
5 connections established
2581197 segments received
2297196 segments send out
63443 segments retransmited
14 bad segments received.
30535 resets sent
Udp:
80731 packets received
351 packets to unknown port received.
1 packet receive errors
31985 packets sent
UdpLite:
TcpExt:
15213 invalid SYN cookies received
159 resets received for embryonic SYN_RECV sockets
622 packets pruned from receive queue because of socket buffer overrun
7 packets dropped from out-of-order queue because of socket buffer overrun
10 ICMP packets dropped because they were out-of-window
15991 TCP sockets finished time wait in fast timer
69 packets rejects in established connections because of timestamp
31774 delayed acks sent
7 delayed acks further delayed because of locked socket
Quick ack mode was activated 55974 times
3 packets directly queued to recvmsg prequeue.
3 bytes directly received in process context from prequeue
1172856 packet headers predicted
152280 acknowledgments not containing data payload received
19065 predicted acknowledgments
847 times recovered from packet loss by selective acknowledgements
Detected reordering 2 times using SACK
Detected reordering 2 times using time stamp
1 congestion windows fully recovered without slow start
3 congestion windows partially recovered using Hoe heuristic
420 congestion windows recovered without slow start by DSACK
3090 congestion windows recovered without slow start after partial ack
1097 TCP data loss events
TCPLostRetransmit: 54
1 timeouts after reno fast retransmit
1302 timeouts after SACK recovery
416 timeouts in loss state
1264 fast retransmits
28 forward retransmits
2097 retransmits in slow start
29729 other TCP timeouts
217 SACK retransmits failed
7416 packets collapsed in receive queue due to low socket buffer
85705 DSACKs sent for old packets
8290 DSACKs sent for out of order packets
2556 DSACKs received
17 DSACKs for out of order packets received
9960 connections reset due to unexpected data
328 connections reset due to early user close
8346 connections aborted due to timeout
TCPDSACKIgnoredOld: 1498
TCPDSACKIgnoredNoUndo: 412
TCPSpuriousRTOs: 27
TCPSackShiftFallback: 5906
IpExt:
InNoRoutes: 1
InOctets: 1851631423
OutOctets: 225338929
To see TCP / UDP network and socket information, use the ss command as follows:
# ss -s
# ss -l
# ss -t -a
# ss -u -a

ifconfig Command Example

Simply type the following command:
# ifconfig
OR
# ifconfig eth0
# ifconfig wlan0

Sample outputs:
wlan0     Link encap:Ethernet  HWaddr 00:21:6a:bf:2d:64
inet addr:192.168.1.100 Bcast:192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::221:6aff:febf:2d64/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:2664664 errors:0 dropped:0 overruns:0 frame:0
TX packets:2394780 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1888550078 (1.8 GB) TX bytes:301911646 (301.9 MB)

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