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Re: Sending ICMP echo request out

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First, I am confused as to if this is two separate requests for help, or one request with two separate people using the same e-mail thread?

If you have one router and two physical hosts, run a tcpdump capture on both hosts and look at them using Wireshark. Most likely the firewall is blocking ICMP echo replies if indeed host two is responding to host's one echo request.

Second, why don't you post your iptables rules here which will help people understand what your iptables router is doing?

iptables -Lvn


Quoting anil dahiya <anildahiya80@xxxxxxxxx>:

Hi ,

I have following setup with routing table as shown below:

+-----------------------+
|    System-1      |
|     "client"         |
|------------------------|
|  192.168.11.5   |
+----------------------+
       |
       |
+------+-----+
|   Switch   +----------------------+
+------+-----+                        |
       |                                 |
       |                       +-------------------------+
       |                        |  192.168.11.1      |
       |                        |---------------------------|
       |                        |     Router            |
       |                        |-------------------------- |
       |                        |   192.168.12.1     |
       |                       +--------------------------+
       |                                    |
       |                                    |
+------------------------+                |
|  192.168.11.6      |                |
|--------------------------|                |
|   System-2        |                |
|--------------------------|                |
|   192.168.12.6    |                |
|                          |----------------+
+------------------------+

Routing table details of setup
------------------------------------------
System-1
-----
$route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.11.0    0.0.0.0         255.255.255.0   U     1      0        0 eth1
0.0.0.0         192.168.11.1    0.0.0.0         UG    0      0        0 eth1


Router
-----------
$route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.12.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1
192.168.11.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0


System-2
------
$route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.12.0    0.0.0.0         255.255.255.0   U     0      0        0 eth1
192.168.11.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0
0.0.0.0         192.168.12.1    0.0.0.0         UG    0      0        0 eth1


When I do ping from system-1 192.168.11.5 to system-2 192.168.12.6 ,
ping echo packet is reaching on system-2 through NIC 192.168.12.6 but
system is not sending any response to 192.168.11.5 using either of NIC
i.e 192.168.11.6 or 192.168.12.6 ? Why this is happening ? Can you
help me ?

I have observed same type of symtoms when I do SSH from 192.168.11.5
to 192.168.12.6

FYI,
ip_forwarding is enable on router and iptables are no configured on
any of system .

Thanks,
Anil
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