Re: Sending ICMP echo request out

[canito@xxxxxxxx]

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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