how to send response via received interface in linux

I have two ether net port.
PC1 eth0 = 192.168.3.131 and also eth1 = 10.10.1.15, gateway =
192.168.3.1
(but this is not a gateway PC ) eth1 is unplugged ( no link) but eth1
is active.

PC2 connects is gatway eth0= 192.168.3.1 eth1= 10.10.1.1
(This PC is connected with gatway PC which connects 192 series and and
10 series network.)

PC3 is in 10 series network eth0=10.10.1.12 .whos gateway is
10.10.1.1

The three PC from intra network.

The Problem is follows
-----------------------
Scenario 1
-----------------
When i pinging 192.168.3.131 from PC3
i.e ] # ping 192.168.3.131
ping 10.10.1.12 from 192.168.3.131 <=== look here, i have
unplugged eth1 but it try to send
ping via
this eth1 automatically...so fails.
request timeout
request timeout
request timeout
request timeout

Scenario 2
-----------------
but when i down the PC1's eth1 down ( by using ]# ifconfig eth1
down ])
after i pinging 192.168.3.131 from PC3
ie]# ping 192.168.3.131
ping 10.10.1.12 from 192.168.3.131 <===== look here i have
told force to use eth0

successfully pings....
sucessfully pingged
sucess......
............
MY need:
------------------
Problem is when eth1 is active , it tries to


how to send response via received interface in linux

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,--- VimaleshS writes:
| I have two ether net port.
| PC1 eth0 = 192.168.3.131 and also eth1 = 10.10.1.15, gateway =
| 192.168.3.1
| (but this is not a gateway PC ) eth1 is unplugged ( no link) but eth1
| is active.

| PC2 connects is gatway eth0= 192.168.3.1 eth1= 10.10.1.1
| (This PC is connected with gatway PC which connects 192 series and and
| 10 series network.)

| PC3 is in 10 series network eth0=10.10.1.12 .whos gateway is
| 10.10.1.1

You've not mentioned any network masks, so I'm assuming your networks are
192.168.3/24 and 10/8 .

| The three PC from intra network.

| The Problem is follows
| -----------------------
| Scenario 1
| -----------------

| When i pinging 192.168.3.131 from PC3
| i.e ] # ping 192.168.3.131

above statements means you're on PC3, and executed "ping
192.168.3.131" i.e. trying to 'ping' PC1's 'eth0' .

| ping 10.10.1.12 from 192.168.3.131 <=== look here, i have

Above sentence means you're on PC1, trying to 'ping' 10.10.1.12 (PC3's
eth0). I'm assuming this statment and the statement above this, are two
different statements, not some typo. So, on PC1, why your ICMP request
is being timed out because you've unplugged 'eth1', leading to 10/8
network unreachable but since 'eth1' is still UP, it'll keep trying
until it times out.

| unplugged eth1 but it try to send
| ping via
| this eth1 automatically...so fails.
| request timeout
| request timeout
| request timeout
| request timeout


| Scenario 2
| -----------------
| but when i down the PC1's eth1 down ( by using ]# ifconfig eth1
| down ])
| after i pinging 192.168.3.131 from PC3
| ie]# ping 192.168.3.131
| ping 10.10.1.12 from 192.168.3.131 <===== look here i have
| told force to use eth0

What to look here, how you forced eth0....

| successfully pings....
| sucessfully pingged
| sucess......
| ...........
| MY need:
| ------------------
| Problem is when eth1 is active , it tries to


| how to send response via received interface in linux

What is received interface ?


Your description above is quite confusing. Please paste proper
output to illustrate what you're trying to say.

- --
Ashish Shukla आशीष श�क�ल http://wahjava.wordpress.com/
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> What is received interface ?
>
> Your description above is quite confusing. Please paste proper
> output to illustrate what you're trying to say.
>
> - --

Let me explain simple senario

One Linux PC1 having two interfaces
eth0 = 192.168.3.131
eth1 = 10.10.1.15 ( Network cable is unplugged)
i.e, eth1 is alive but Ethernet cable is not connected in that
interface
gateway = 192.168.3.1


When i ping address 10.10.1.2 from PC1
it sending request from
Output
-======
# ping 10.10.1.2
ping 10.10.1.2 from 10.10.1.15
Request timeout
Request timeout

Problem is when i ping Class A network it tries to send
packets from eth1 interface , but Ethernet cable is unplugged

But if it tried to send packets from
Output
======
# ping 10.10.1.2 eth0
ping 10.10.1.2 from 192.168.3.131
Successfully pings

Here i forced ping to use eth0 interface so it pings successfully.

.......But in case of FTP
If i ftp 10.10.1.2 .from PC1..
FTP fails ........
because i cannot able to force to use the eth0 interface in FTP as i
did
in ping .

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,--- VimaleshS writes:
|| What is received interface ?
||
|| Your description above is quite confusing. Please paste proper
|| output to illustrate what you're trying to say.
||
|| - --

| Let me explain simple senario

| One Linux PC1 having two interfaces
| eth0 = 192.168.3.131
| eth1 = 10.10.1.15 ( Network cable is unplugged)
| i.e, eth1 is alive but Ethernet cable is not connected in that
| interface
| gateway = 192.168.3.1


| When i ping address 10.10.1.2 from PC1
| it sending request from
| Output
| -======
| # ping 10.10.1.2
| ping 10.10.1.2 from 10.10.1.15
| Request timeout
| Request timeout

I asked you paste the proper output.

| Problem is when i ping Class A network it tries to send
| packets from eth1 interface , but Ethernet cable is unplugged

| But if it tried to send packets from
| Output
| ======
| # ping 10.10.1.2 eth0
| ping 10.10.1.2 from 192.168.3.131
| Successfully pings

I asked you paste the proper output. probably you missed some argument
to 'ping'.

| Here i forced ping to use eth0 interface so it pings successfully.

Anyways, I'm assuming you're using '-I' switch of 'ping' utility to
specify the outgoing interface.

| ......But in case of FTP
| If i ftp 10.10.1.2 .from PC1..
| FTP fails ........
| because i cannot able to force to use the eth0 interface in FTP as i
| did
| in ping .

Because, there's already a route to 10/8 network present. Default
route won't be used unless you remove 10/8 network route. So whatever
network utility you use, if it allows you to explicitly specify
outgoing interface, then you don't need to modify your routing table
to use that utility, but if that don't then you need to modify your
routing table.

HTH
- --
Ashish Shukla आशीष श�क�ल http://wahjava.wordpress.com/
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