ip
show / manipulate routing, devices, policy routing and tunnels
Synopsis
ip [
OPTIONS ] OBJECT { COMMAND |
help }
OBJECT
:= { link | addr | addrlabel |
route | rule | neigh | ntable |
tunnel | tuntap | maddr | mroute
| mrule | monitor | xfrm | netns
| l2tp | tcp_metrics }
OPTIONS
:= { -V[ersion] |
-s[tatistics] |
-r[esolve] |
-f[amily] { inet | inet6 |
ipx | dnet | link } |
-o[neline] }
add an example, a script, a trick and tips
examples
source
What does "network" mean in the /etc/network/interfaces file?
For your case, network is 192.168.1.0, which means
your ip address is in the network range, 192.168.1.0 to
192.168.1.255
You can always get your network base address easily by doing
ip & mask, where & is logical AND.
source
ip versus ifconfig
Simple answer: On Linux ifconfig is obsolete.
From man ifconfig:
This program is obsolete! For replacement check ip
addr and ip link. For statistics use
ip -s link.
source
How can I list all IPs in the connected network, through Terminal preferably?
In windows this would be "arp -a" I believe that an
equivalent of that in Linux would be "arp -e".
This information can be found from the man page for arp :
arp with no mode specifier will print the current content of the table.
-e : Use default Linux style output format (with fixed columns).
source
Three computers accessing internet but only two network interfaces showing in ´ifconfig´, why?
I am not sure if I understand correctly. But you have 1 Wireless
gateway and 3 Devices connected to it?
So doing ifconfig only shows PHYSICAL hardware/connections
on the PC that ran the command - not the connections available or
other device.
ifconfig stands for interface configuration
-
An interface if a virtual or physical layer on the computer
that enables it to communicate with other devices using a
standard, for example in your case TCP/IP
-
eth0 could be your Wired Network card running at
10/100/1000
-
eth1 is possibly your wirless interface running at
a/b/g/n speeds.
-
lo is a virtual interface and is called a loopback
and bind to your computer using home (127.0.0.1) or (localhost)
or whatever your computers name is(because it loops back to it
self)
To see other computers you need to use something like ARP and to find other computers or devices within
your network range.
Also as suggested you can use a wireless tool iwconfig to scan for access points (an access
point is not an interface- but the access point it self uses an
interface to communicates with other devices found in ARP)
And you only have 1 internet connection, not 3.
In total you should have 5 ARP entries - 2 PC's,
1Notebook, 1Switch and 1 Modem
So as you can see in the illustration, each host has an interface
of eth0, the gateway has eth0 and the ISP on the other side has
eth0. the more interfaces a device has the higher the number.
source
How to route only specific subnet (source ip) to a particular interface?
You must use the route command. For example if you want to route
all ip of 192.168.1.xxx to a particular device you have to use
the following command:
route add -net 192.168.1.0 netmask 255.255.255.0 dev eth0
With that command you say that all the packets sent from that
subnet must be sent to the eth0 interface. If you need to add
also a gateway for that connection you can use that:
route add -net 192.168.1.0 netmask 255.255.255.0 gw 192.168.1.1
source
What is the maximum number of IPs that can be assigned to a given computer?
More than you could ever possibly need. Use ip addr
add to add addresses to an interface.
source
In Ubuntu, routes are not added as defined in rc.local file....why?
rc.local is not the best place to set up additional NIC aliases
and routes.
Just use /etc/network/interfaces for that.
NIC alias example
static routes example
Concerning your problem:
you use an absolute path to the ifconfig tool, but a relative
path to the ip tool. Try using an absolute path there too. Find
it by using which ip or whereis ip.
source
finding IP address using Linux command prompt
If your machine is assigned a local IP address, it may not know
your public-facing address. You can query a server not on your
local network to discover your public-facing address.
$ curl whatismyip.org
source
Check external IP from a Linux headless server
The follwoing will do the trick.
curl -s checkip.dyndns.org | grep -Eo '[0-9\.]+'
source
Use Shorewall to port-forward requests based on the domain requested to different servers
Shorewall (more specifically, iptables) works in the
transport layer and is not suitable for making
decisions based on application layer HTTP information. What you
want is a reverse proxy server. nginx is a good option.
source
Resolving hostnames without DHCP
DHCP does not do hostname resolution; it just offers a method for
automatic registration on a locally running DNS server.
Your choices are:
-
mDNS (avahi-daemon + nss_mdns) –
names are always in the form name.local;
used natively in Mac OS X and available for Windows; uses
multicast.
-
NBNS (Samba nmbd + nss_wins) – used
by Windows and compatible with Mac OS X; uses broadcast
packets.
-
Edit /etc/hosts on each computer:
192.168.1.2 computerone
source
Same IP for WLAN and ethernet on Linux
I'm not sure keeping the same IP will help but this might just
work:
- Connect with cable and set your IP address manually.
- Pull the cable and set the the same IP address manually and
also change the MAC address to your Ethernet MAC.
- Disable DHCP on the WiFi router (I assume that you connect to
the same router via cable and wireless).
Setting the IP address can be done in the network manager if
you're using a typical Gnome setup.
You don't necessarily have to disable DHCP, my router has options
to give DHCP addresses e.g. only above 192.168.0.10. So I can set
manual addresses 192.168.1.[2-9] and DHCP addresses will start
from 192.168.1.10. In such a situation you could try setting both
your wired and wireless IP to 192.168.1.5.
source
ssh: connect to host port 22: Connection refused with external ip address
Are you sure you did the correct thing on the router (i.e. does
this work with another port on an other service already)?
I'm asking because "connection refused" happens on TCP level and
the reason usually is that either nobody is listening on that
port on the target machine (that would be the equivalent of sshd
not running) or some firewall blocking it.
Since you say it works with an address of your local network, it
would appear to be the router that's either not doing the
forwarding or forwards to something else.
source
routing a secondary IP-addr. of a different private network on the same interface
iptables -t nat -A POSTROUTING -o wlan2 -j SNAT -s
172.16.1.62/24 --to-source 192.168.1.63
Seems to do just that:
# telnet -b 172.16.1.62 google.com 80
Trying 173.194.32.33...
Connected to arn06s02-in-f1.1e100.net.
Escape character is '^]'.
options
-V,
-Version
print the version of the
ip utility and exit.
-s,
-stats, -statistics
output more information. If the
option appears twice or more, the amount of information
increases. As a rule, the information is statistics or some
time values.
-l,
-loops
Specify maximum number of loops
the ’ip addr flush’ logic will attempt before
giving up. The default is 10. Zero (0) means loop until all
addresses are removed.
-f,
-family
followed by protocol family
identifier: inet,
inet6,bridge,ipx,dnet or
link, enforce the protocol family to use. If the
option is not present, the protocol family is guessed from
other arguments. If the rest of the command line does not
give enough information to guess the family, ip falls
back to the default one, usually inet or any.
link is a special family identifier meaning that no
networking protocol is involved.
-4
shortcut for -family inet.
-6
shortcut for -family inet6.
-B
shortcut for -family bridge.
-0
shortcut for -family link.
-o,
-oneline
output each record on a single
line, replacing line feeds with the ’\’
character. This is convenient when you want to count records
with wc(1) or to grep(1) the output.
-r,
-resolve
use the system’s name
resolver to print DNS names instead of host addresses.
ip - command syntax
OBJECT
address
- protocol (IP or IPv6) address on a device.
addrlabel
- label configuration for protocol address selection.
l2tp
- tunnel ethernet over IP (L2TPv3).
link
- network device.
maddress
- multicast address.
monitor
- watch for netlink messages.
mroute
- multicast routing cache entry.
mrule
- rule in multicast routing policy database.
neighbour
- manage ARP or NDISC cache entries.
netns
- manage network namespaces.
ntable
- manage the neighbor cache’s operation.
route
- routing table entry.
rule
- rule in routing policy database.
tcp_metrics/tcpmetrics
- manage TCP Metrics
tunnel
- tunnel over IP.
tuntap
- manage TUN/TAP devices.
xfrm
- manage IPSec policies.
The names of all objects may be written in full or abbreviated
form, f.e. address is abbreviated as addr or just
a.
COMMAND
Specifies the action to perform on the object. The set of
possible actions depends on the object type. As a rule, it is
possible to add, delete and show (or
list ) objects, but some objects do not allow all of these
operations or have some additional commands. The help
command is available for all objects. It prints out a list of
available commands and argument syntax conventions.
If no command is given, some default command is assumed. Usually
it is list or, if the objects of this class cannot be
listed, help.
reporting bugs
Report bug to the Network Developers mailing list
<netdev[:at:]vger.kernel[:dot:]org> where the
development and maintenance is primarily done. You do not have to
be subscribed to the list to send a message there.
history
ip was
written by Alexey N. Kuznetsov and added in Linux 2.2.
see also
ip-address,
ip-addrlabel, ip-l2tp,
ip-link, ip-maddress,
ip-monitor, ip-mroute,
ip-neighbour, ip-netns,
ip-ntable, ip-route, ip-rule,
ip-tcp_metrics, ip-tunnel,
ip-xfrm
IP Command reference ip-cref.ps
author
Original
Manpage by Michail Litvak <mci[:at:]owl.openwall[:dot:]com>