Review your favorite Linux distribution.
Go Back > Forums > Linux Forums > Linux - Networking
User Name
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.


  Search this Thread
Old 08-19-2010, 10:32 AM   #1
LQ Newbie
Registered: Aug 2010
Posts: 1

Rep: Reputation: 0
Question ICMP response not sent to a local network ip

My problem is simple, but i am not sure if i can explain clearly here. Let me try

icmp request from an ip that is in the same network as one of the local interfaces is not responded to, if the ping request is received via an interface in a different network. Is this some security feature?

Consider the below network


RTR - Router
x.1 -> 192.168.x.1
LNX - Linux machine

RTR1's x.1 and LNX's x.3 are connected together.

Static routes added:
RTR1 - net z.0 gw y.2

I send a ping from RTR1 to z.3 with source IP x.1
I expect the ping to be responded by the LNX (response to be sent viz x.3<->x.1 link)
This doesn't happen

If I change the route in RTR1, making x.3 as the gw, it starts working fine.

Looks like some security feature in Linux prevents this ping response from being sent.

More light into this will help!

Old 08-19-2010, 03:27 PM   #2
Senior Member
Registered: Nov 2004
Location: Texas
Distribution: RHEL, Scientific Linux, Debian, Fedora
Posts: 3,935
Blog Entries: 5

Rep: Reputation: Disabled
First, please don't use that special font. It makes reading your post harder, not easier. (For network diagrams and command output, etc., do use code tags.)

So your Linux host has two separate routes by which it can reach Router1, correct?

If so, let's see the output from the following two commands:
# netstat -rn
# ip rule show


icmp, ping

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
ICMP requests from Content Delivery Network jlarsen Linux - Networking 1 07-17-2008 10:34 PM
snmp + no response from local host aeby Linux - Server 2 08-29-2007 09:29 AM
Slow local web response on Fedora Core 5 Heinz09 Linux - Server 1 06-26-2007 01:58 PM
fake icmp response c0lin Linux - Security 3 01-22-2005 01:06 AM
BIND 9: Slow response from root servers. Local is ok. Apollo77 Linux - Networking 3 01-14-2005 11:22 AM > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 05:42 AM.

Main Menu
Write for LQ is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration