how i can create taptun or loopback in centos

mr-secret · 04-05-2015, 11:50 AM

hello guys
iwant create a taptun or loopback interface and share net from eth0 to this
please help me about this thanks
my os is centos 5
thanks

estabroo · 04-06-2015, 08:28 AM

While creating a tap/tun is fairly easy, I'm not sure what you are trying to achieve. Your wording seems to indicate that you want to bridge them.

Easiest way to make one, modprobe tun and then use tunctl to create it.

excerpt from man page
tunctl [-f tun-clone-device] [-u owner] [-t device-name]
tunctl [-f tun-clone-device] -d device-name

generally you won't need to use the -f option unless your tap/tun master is in an odd place

mr-secret · 04-06-2015, 10:06 AM

Quote:

Originally Posted by estabroo

While creating a tap/tun is fairly easy, I'm not sure what you are trying to achieve. Your wording seems to indicate that you want to bridge them.

Easiest way to make one, modprobe tun and then use tunctl to create it.

excerpt from man page
tunctl [-f tun-clone-device] [-u owner] [-t device-name]
tunctl [-f tun-clone-device] -d device-name

generally you won't need to use the -f option unless your tap/tun master is in an odd place

hi thanks for your replay
sorry for bad speak english
i do like this in windows that create a ms loopback interface and share internet from main interface to loopback
and want do this steps in centos
create a loopback interface and share internet too
i hope understand my mean
thanks

estabroo · 04-07-2015, 03:04 PM

Can you make a network diagram showing what you'd like to do?

The reason I'm asking for a diagram is to help figure out what you'd like to do. Centos already has a network loopback, it's the lo interface. So I'm guessing your looking for something more like

Code:

computer A (eth0) <-> (eth1) Computer B (eth0) <-> Internet   where you want A to be able to get to the internet

Or

Computer B (eth0) <-> Internet                                    (eth0) Computer A
        (vpn tun) <---------------------------------------------> (vpn tun)

Though that last scenario would require A to have internet access already

mr-secret · 04-07-2015, 03:28 PM

hello ok sure
i have a software that need a loopback interface with internet so i do this in windows like this diagram
pictures diagram step by step and i want do this on the centos server

local area connection = main interface
local area connection 2 = loopback interface

http://uploads.im/b5YHo.png

http://uploads.im/903yf.png

http://uploads.im/7ZpXk.png

i want do look like this diagram work on the centos server

estabroo · 04-07-2015, 04:10 PM

So does the Centos server have just one ethernet card hooked up or multiple?

If it's just a single interface then something like this would work. Using those pictures as the prefix you'd like this on.

Add an ip alias (this is your loopback equivalent)

Code:

  Temporary - ifconfig eth0:share 192.168.0.1 netmask 255.255.255.0
  Permanent - for centos you'll need to go into /etc/sysconfig/network-scripts and copy ifcfg-eth0 to ifcfg-eth0:share and update the device and ip information in that file

Turn on ip forwarding:

Code:

  Temporary - echo 1 > /proc/sys/net/ipv4/ip_forward or sysctl -w net.ipv4.ip_forward=1
  Permanent - edit your sysctl file, typically /etc/sysctl.conf, look for the line that says net.ipv4.ip_forward, switch it from a 0 to a 1

Tell your computer to masquerade for the other hosts:
iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j MASQUERADE

192.168.0.0/24 is the cidr notation for the prefix containing the ip address assigned to the ip alias eth0:share

You'll want to save that iptables stuff with something like - /sbin/service iptables save
so that it'll be there after a reboot. I'd try it out first to make sure it's doing what you want before saving it.

Then just tell the other computers sharing it that the Centos server aliased ip address (192.168.0.1) is their default route, which will vary depending on what OSes they are.

mr-secret · 04-07-2015, 04:26 PM

ok thanks man
yes this diagram just have one loopback interface
this diagram should be work
i need test this and reply soon
again many thanks

mr-secret · 04-09-2015, 12:16 AM

i do this diagram
so my software unfortunately cannot detect the loopback interface in linux (but in windows no have problem )
and i try add one more interface
im using vmware vsphere for my operation systems and add new virtual interface in normally detect and i continue to diagram
my diagram complete but still in linux have problem and not working

if you want i can send info for chek this and better understand my mean
thanks estabroo

estabroo · 04-10-2015, 07:53 AM

Any information would be helpful. I don't know anything about vsphere so I probably won't be much help there.

Are you saying the Centos server is running in vsphere? If so, outside stuff won't see that ip alias unless the virtual ethernet is bridged in vmware

mr-secret · 04-21-2015, 04:12 PM

ok look this link i want get this configure:

https://www.digitalocean.com/communi...sing-softether

all steps will be ok . i have problem just in step7
this guide say two ways for NAT and tech me for secure nat but i want use local brdige with dhcp server
please guide me for this
thanks