cannot ping local computer(s)

thea · 2011-01-03 20:15:52

I have an Asus laptop with wired and wireless cards. Remote connections on wireless work fine. However, for about 2 weeks I have not been able to ping the computers on my LAN, although they can ping each other without problem. The laptop can ping itself. I have run all the usual diagnostics. One curious thing is happening. The original static IP of my laptop was 192.168.0.4. When I changed this to 192.168.0.2 in my rc.conf, the IP address reverts back to 192.168.0.4 after using the Wicd Network Manager (by "revert back" I mean what is showing both in GUI and after running ifconfig). This itself however is not causing the ping failure.

About 2 weeks I also installed Firestarter, having run my wireless connections (briefly) without any kind of firewall. Although I allowed connections to both of the other computers on my LAN, I was not able to ping, and subsequently removed Firestarter and iptables (pacman -Rns), which however did not fix the connectivity problem. My suspicion is that somewhere there is a configuration file which is messed up, but I haven't a clue which. Does anyone have any suggestions?

Thanks,

Thea

rickdg · 2011-01-03 23:14:32

I don't know about the configuration files, but some general troubleshooting questions:

Could the IP change to 192.168.0.4 be caused by a DHCP lease or a setting in Wicd?
Is the disruption in ping two-way? That is to say, can you ping your Asus from your desktop?
Some routers separate the wireless from the local area network, which could cause the ping to fail. Have you recently reset your router's settings?

Having a funny network problem is like having a mosquito in your room, you have to get rid of it before you can go to bed

thea · 2011-01-03 23:58:10

Thanks for your reply, rickdg! Having conducted quite a few web searches on this problem I know that it does not elicit many responses.

My LAN consists of three computers: 192.168.0.4 -- my laptop
192.168.0.6 -- my regular work computer
192.168.0.7 -- my server
as well as a printer: 192.168.0.5
all connected with a switch (Syslink SD205)

The ping problem is from either .6 or .7 to the laptop (.4), and vice-versa. It's as if there is something in .4 which is blocking all net traffic, both in and out. Between .6 and .7 it is fine, i.e. pinging works as expected.

In addition, I have a NetComm HSPA Wifi Router with the IP address of 192.168.0.3 which I currently use with my laptop only (wlan0 is statically set at 192.168.0.4). As far as I can tell, there are no DHCP leasing problems. When using the Wifi router, I am not connected to my LAN (although I would like to be), so the ping failure occurs when I use Wicd to disconnect from the wireless net and connect to the wired net. However the problem also has nothing to do directly with Wicd, since my default setting is the wired net, and on booting up and even before starting X, pinging to and from .4 is impossible ("Destination Host Unreachable"). And finally yes I did reset my router's IP address -- it was originally 192.168.1.1. When I got the wireless and set it up, I had no problems whatsoever with my wired network connections, disconnecting and connecting from and to the wireless net as needed. It was only after installing Firestarter that I got the ping problem from the laptop (which is the only computer I installed it on). Unfortunately, I just moved, so in the past two weeks I have not had the opportunity to determine exactly when the problem first occurred, or what exactly might have caused.

Thanks again,

Thea

fukawi2 · 2011-01-04 01:49:30

Is iptables dropping the ping packets?
`iptables -nvL`

Are you able to ARP the laptop?
`arping 192.167.0.4`

thea · 2011-01-04 22:34:29

Hi fukawi2

Thanks for your suggestions. I don't have iptables -- I did install it, but then removed it as part of my troubleshooting (I didn't have iptables prior to this problem).

arping gives no results (just sits and does nothing, when stopped I get the message that so and so many packets were sent without response.

I have re-configured my network. Now my main (work) computer is connected to the switch, which is connected to the wireless router. This works fine. My laptop is now connected to the switch as well. As before, pinging from or to the laptop produces no results. On bootup, I get a FAIL message when the rc.conf network settings are read (eth0 now set to dhcp). Despite this, on bootup ifconfig still works, giving me the old IP address of 192.168.0.4, which I can't seem to get rid of. Also Wicd still does not complain when I use it to activate the wired network connection. However I can only ping the router, and only when in wireless mode (which works fine).

It still looks to me that there is a config file somewhere that is messed up.

Thanks again,

Thea

Arch Linux

#1 2011-01-03 20:15:52

cannot ping local computer(s)

#2 2011-01-03 23:14:32

Re: cannot ping local computer(s)

#3 2011-01-03 23:58:10

Re: cannot ping local computer(s)

#4 2011-01-04 01:49:30

Re: cannot ping local computer(s)

#5 2011-01-04 22:34:29

Re: cannot ping local computer(s)

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