Weird Network Connections

[NUtack97]

Hi all,

I haven't found anything useful in the forums, so here goes:

I have a Mandrake 9.1 box connected to the 'net using eth1 and also connected to my lan on eth0 (192.168.1.1). Now I got a basic firewall setup using IP-Masquerading-HOWTO and I can connect to the 'net with either my Linux box or any computer on the LAN.

The weird part is this: I cannot ping eth0 from either my linux box or LAN :confused: . The web server seems to work fine from anywhere, so I have a feeling it's something to do with IPTABLES, but being a newbie, I have no idea how to interpret the tables at this point. Another tidbit is that I cannot ssh from my lan to the linux box, either.

Any help would be most appreciated. Thanks in advance!

[chrism01]

On the Linux box, tun:
iptables -L
which will tell you the current setup. You can start from there.

[DMR]

Ping uses the ICMP protocol; if the problem really is with iptables, look for a rule related to ICMP; that's what you'll need to change.

[NUtack97]

Another thing that's really weird here...It seems that every few hours (I don't know the exact time right now) my Lan NIC loses its IP address. I have it set statically (I'm pretty sure) to 192.168.1.1 but at some random point, I lose 'net access on one of my LAN boxes, and when I go to my Linux Box and type 'ifconfig', eth0 (lan NIC) doesn't show any ip addresss. I type in ifup-eth0 and all is well, but I shouldn't have to do this every few hours. Any clues?

[Magueta]

What are the contents of your ifcfg-eth0 file?

Joe

[NUtack97]

Here's my ifcfg-eth0 file:

DEVICE=eth0
BOOTPROTO=static
IPADDR=192.168.1.1
NETMASK=255.255.255.0
NETWORK=192.168.1.0
BROADCAST=192.168.1.255
ONBOOT=yes

Any ideas? I really don't know what I'm looking for with that ICMP stuff...Is that a specific port, or is it a group of ports? I'm really clueless on that stuff.....

[Magueta]

You can receive ICMP requests on any port. ICMP is a protocol like TCP or UDP so the port you receive it on depends on what you're doing. Chris seems like he's on to something with the command iptables -L or ipchains -L, please post the results of that command. Also, check your logs in /var/logs/, more specifically the file "messages" in that directory and see if there are any messages about eth0 or something about a network error or failure it might help you figure out why the ethernet card seems to keep cutting out.

Joe

[paul.shelb]

Might be a good idea to add this to your ifcfg-eth0 too:

USERCTL=no


...just a thought.

[baldguy]

what does this command return?
cat /proc/sys/net/ipv4/icmp_echo_ignore_all
if it comes back 1 then your machine is set to ignore all icmp echo requests (pings)

[paul.shelb]

...maybe attach your /etc/sysconfig/iptables file too

;)

[NUtack97]

Guys,

Thanks for all the replies...I seem to be having nothing but troubles with this Mandrake 9.1 including the following:

-GUI won't start, keeps telling me that my DCOPserver isn't started

-When the GUI was working, it wouldn't exit out completely, would only show partially the windows I did have open but allowed NO input whatsoever, forcing me to hit the RESET button

-emacs won't run at all at command-line (can't find emacs, even though I KNOW I installed it)

-I don't have elm (only command-line email I know how to use) and have no idea what else to use

-Damn security stuff driving me bonkers

-Can't ping to lan NIC even after changing that icmp_echo_ignore_all to '0'

-Lan NIC NEVER starts up on its own, I have to manually type ifup eth0 to get it working

-And many more I won't bother to detail...

I'm going back to my Mandrake 8.1 cd's...At least I was able to get that running to my liking. <ranting> I thought this new release was supposed to make it easier!? Instead, it's making it more difficult and a royal pain in my arse!!! Screw this 'latest and greatest' stuff, I've had it!? </ranting>