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Home > Archive > Linux/Unix > October 2001 > Need Help With RH 7.1 LAN Problem
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Need Help With RH 7.1 LAN Problem
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| doctorcisco 2001-10-12, 5:23 pm |
| Hi all!
I'm a Linux newbie; I'm a regular in the Cisco forums on this site. I'm setting up a RH 7.1 box, and am having the following problem. Can anyone help?
The box is a standard Pentium class machine. I have an ISA NE2000 clone NIC installed, IRQ 11, I/O 0x300. When I installed RH, I of course had to manually enter these values because the NIC is not Plug & Play. RH said it found the card successfully. I've set it up with an IP address and mask, etc.
When I boot the box, it successfully initializes eth0. The box can ping itself on 127.0.0.1, and on its IP address 192.168.1.26. When I ping anything else in the subnet, it replies with a "destination unreachable."
The hub happens to be the hub built into a Cisco 2516 router, which means I could do some additional troubleshooting. When I try to ping the router from the RH box, its address is entered into the ARP cache on the router with its correct MAC address. However, the pings fail, and the ARP cache on the RH box labels the ARP entry for the router "incomplete" when I issue an arp -e command in bash. The RH arp cache shows 192.168.1.1 (the router ethernet interface), but no MAC address for the router interface.
After I try to ping the router from the RH box, I clear the ARP cache on the router. I then try again to ping the router. But the RH box does not get back into the router ARP cache again until it is rebooted and I retry the ping. (In other words, the RH box does not ARP for the router again after the initial ping attempt, even though the RH arp cache is incomplete). In addition, the router shows the hub port up when the RH box is running.
Sendmail also hangs at boot for some reason; it eventually times out the initialization and completes the boot. Perhaps when I changed the IP address on eth0 with netcfg during my troubleshooting, sendmail got confused about its network interfaces?
I've swapped cables, NIC's, hub ports, and IP addresses on the RH box. Any other ideas out there on what the problem is?
TIA,
doctorcisco | |
| TW2001 2001-10-12, 5:55 pm |
| OK.Sendmail if you type ntsysv at the command line, it will bring up a menu of services that will intialize at boot.This is the quickest easiest way to take care of that issue.
Next, install Linuxconf.Its on the second RH7.1 install cd.This tool will make your life a lot less frustrating as you learn.
In the routing and gateways tab...make your linux box aware of the router.This should get you going.
Have you got connectivity with any other boxes on the network? If not if you dont you need to look at the hosts files.
I can(and another far more knowledgable reg here) can point you to the files but the networking is networking
Let us know how you make out.
And becouse i care
ftp://ftp.redhat.com/pub/redhat/red...owertools/i386/ | |
| doctorcisco 2001-10-12, 7:47 pm |
| quote:
Originally posted by TW2001
OK.Sendmail if you type ntsysv at the command line, it will bring up a menu of services that will intialize at boot.This is the quickest easiest way to take care of that issue.
Next, install Linuxconf.Its on the second RH7.1 install cd.This tool will make your life a lot less frustrating as you learn.
In the routing and gateways tab...make your linux box aware of the router.This should get you going.
Have you got connectivity with any other boxes on the network? If not if you dont you need to look at the hosts files.
I can(and another far more knowledgable reg here) can point you to the files but the networking is networking
Let us know how you make out.
And becouse i care
ftp://ftp.redhat.com/pub/redhat/red...owertools/i386/
Thanks for the quick response!
The box connects to NOTHING on the LAN ... that's my problem. RH seems happy with the module for the card, initializes it successfully, and its MAC address gets into the arp cache of whatever it tries to ping, the first time it tries to ping it. However, the RH box always fails to hear any responses, and always fails to get anything on the LAN into its arp cache. I can do the network stuff (I DO know my tcp/ip etc, being a WAN weenie). I'm not worried about *routing* the traffic, for now I just want to ping the $&#@)* router interface. 
I'm 99.99% sure I've eliminated hardware (tried 2 different NIC's, 2 hub ports, 2 cables -- all 6 are known good). My choices seem to be:
1) These old ISA Taiwanese NE2000 clones aren't QUITE getting along with the Linux NE2000 device driver. However, I've never had any problems using these NIC's with DOS/Windoze using whatever default NE2000 drivers.
2) Some weird issue with how I configured RH. Always possible; I'm newbie and all that. However, I did use the correct setup at installation, and RH DID find the NIC at install, and DOES successfully initialize eth0 at boot, and successfully gets an ARP request onto the wire (since RH box's address is in the router's arp cache) -- it just isn't hearing the answer, it would appear. I did go through netcfg, netconfig and linuxconfig; everything looked right and seemed happy. BTW, I told the install routine not to put use any firewalling, so that shouldn't be the problem.
3) I don't think its a host file issue, since I'm pinging to IP addresses (router at 192.168.1.1, another router at 192.168.1.230, and Windoze workstations at .99 and .50).
4) Could it perhaps be a routed issue? If it were, though, I'd think no arp would hit the wire at all ...........
I'll take a stab at ntsysv for the sendmail issue.
Thanks again for the time, and hoping for the magical answer,
doctorcisco
P.S. I have a copy of the power tools, but don't have anything installed off of it yet. Anything on there to help troubleshoot this beast? LOL | |
| TW2001 2001-10-12, 8:22 pm |
| Strange, if your hitting others on the wire.
Sniff it out
http://www.ethereal.com/ (excellent...being a cisco guy you will love this.)
I would watch capture the packets that are reaching destination and compare them with your problem.
I dont think it would be routed.Unless you configured it.
Try to configure static routes to those address (you could even point the traffic through the successful route of one of the routers)
"The box connects to NOTHING on the LAN ... that's my problem. "
"I don't think its a host file issue, since I'm pinging to IP addresses (router at 192.168.1.1, another router at 192.168.1.230, and Windoze workstations at .99 and .50)".
Just so Im clear you can succesfully ping other addresses on the network?
I have a ping...
ping ccieTobe! | |
| ccieToBe 2001-10-12, 8:44 pm |
| This is really strange. I'm with TW2001, you should use a traffic sniffer to see exactly what's going on.
Is the NIC hearing traffic from more then one subnet? I've seen some very strange things happen to the ARP cache on *nix boxes with that type of setup. If there is more then one subnet try reducing it to one and clearing the ARP cache. I know that isn't an acceptable solution, but if it works you at least know what the problem is.
*nix doesn't like ISA hardware for some reason. If you have any spare PCI nics try one of them out. | |
| doctorcisco 2001-10-12, 11:53 pm |
| quote:
Originally posted by ccieToBe
This is really strange. I'm with TW2001, you should use a traffic sniffer to see exactly what's going on.
I'll take a shot at that .. the problem being I built the RH box, in part, so I could have a freebie sniffer ... LOL.
quote:
Is the NIC hearing traffic from more then one subnet?
Nope. This is a really simple setup; a 192.168.1.x network that happens to have a couple of router interfaces in it.
I can't ping anything on the network. Period. But I get into the router's arp cache.
I'll report back after I have some time to fiddle a bit.
doc | |
| doctorcisco 2001-10-18, 1:27 pm |
| Well, I finally got a sniffer on the wire. The results are somewhat puzzling.
When I ping from the RH box, the ARP and the reply from the destination appear on the wire. However, the reply is never entered into the arp cache on the RH box.
When I ping the RH box from another machine, the RH box does not reply to the arp request.
All in all, it appears that my RH box can talk, but cannot hear.
Any ideas?
doc | |
| doctorcisco 2001-10-18, 4:59 pm |
| quote:
Originally posted by doctorcisco
Well, I finally got a sniffer on the wire. The results are somewhat puzzling.
When I ping from the RH box, the ARP and the reply from the destination appear on the wire. However, the reply is never entered into the arp cache on the RH box.
When I ping the RH box from another machine, the RH box does not reply to the arp request.
All in all, it appears that my RH box can talk, but cannot hear.
Any ideas?
doc
One more tidbit ... when I run ifconfig eth0, it shows several hundred Rx packet drops, and none successful. Why would the box be dropping the Rx packets?
TIA,
doc | |
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| hey doc,
It has been a while since I installed RH but something to check:
I remember on installation that you could set up a firewall/filter and the installation asked at what level you wanted to set the filter. You could also customize this feature. Is it possible that the tcp/ip filter was set to not accept certain items/protocols?
It is similiar to the security content feature on MS IE.
Just a thought.
ea | |
| dmaftei 2001-10-19, 7:48 am |
| quote:
Originally posted by doctorcisco
... when I run ifconfig eth0, it shows several hundred Rx packet drops, and none successful.
Looks a lot like you have a faulty NIC. Why don't you take ccieToBe's advice and try a PCI card?
Cheers! | |
| ccieToBe 2001-10-19, 4:29 pm |
| quote:
Originally posted by dmaftei
Looks a lot like you have a faulty NIC. Why don't you take ccieToBe's advice and try a PCI card?
Cheers!
I think dmaftei's right. Either you have a bad NIC or it's not installed correctly. The fact that you're getting traffic out but not in makes it sound like it's probably a bad NIC. Do you get the exact same traffic sniffing results when you're trying out the other NICs? | |
| doctorcisco 2001-10-21, 9:54 am |
| quote:
Originally posted by ccieToBe
I think dmaftei's right. Either you have a bad NIC or it's not installed correctly. The fact that you're getting traffic out but not in makes it sound like it's probably a bad NIC. Do you get the exact same traffic sniffing results when you're trying out the other NICs?
I've tried 2 NIC's (both are the same kind), two patch cables, and 2 hub ports. Same results each time. 
The other oddity that makes me think it's not hardware is all the dropped Rx packets I see in "ifconfig eth0". If it's hardware, presumably I shouldn't have any Rx packets at all.
When I did the install, I chose the no firewall option, so it shouldn't be that.
Don't have any PCI NIC's in the junk box at home ... I did find an old ISA 3Com 503 I may try next. If that doesn't help, I guess I'll have to break down and spend $20. I just have this gut feeling that's not where the problem is. It sure looks like the packets are arriving and being dropped before they go up the stack.
doc the frustrated | |
| ccieToBe 2001-10-21, 2:22 pm |
| quote:
Originally posted by doctorcisco
I've tried 2 NIC's (both are the same kind), two patch cables, and 2 hub ports. Same results each time.
The other oddity that makes me think it's not hardware is all the dropped Rx packets I see in "ifconfig eth0". If it's hardware, presumably I shouldn't have any Rx packets at all.
When I did the install, I chose the no firewall option, so it shouldn't be that.
Don't have any PCI NIC's in the junk box at home ... I did find an old ISA 3Com 503 I may try next. If that doesn't help, I guess I'll have to break down and spend $20. I just have this gut feeling that's not where the problem is. It sure looks like the packets are arriving and being dropped before they go up the stack.
doc the frustrated
Another thing it may be is that those NICs aren't supported. I had this experience yesterday -- loaded FreeBSD on my laptop and installed a 3COM 802.11b NIC. After I recompiled the kernel the NIC was installed and appeared to be fine until I tried to bind it to an access-point. I got some error messages that it wasn't able to connect. After some searching I was able to find that this NIC isn't supported yet even though it appears to install correctly. | |
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| quote:
Originally posted by doctorcisco
Don't have any PCI NIC's in the junk box at home ... I did find an old ISA 3Com 503 I may try next. If that doesn't help, I guess I'll have to break down and spend $20. I just have this gut feeling that's not where the problem is. It sure looks like the packets are arriving and being dropped before they go up the stack.
doc the frustrated
I've had a 3com etherlink III ISA, netgear fa311 PCI and a linksys 100tx PCI nics on my RH7.1 box ( a very old P166 ). No problems.
It is kind of curious about the dropped packets.
Have you tried command " # ipchains -L "
That should tell you of any denys you on the interface. ipchains rules work very much like cisco access lists. It still sounds to me like some sort of packet/protocol filtering.
Of course, I could be way out in left field on this one
hth
ea | |
| ccieToBe 2001-10-21, 4:25 pm |
| quote:
Originally posted by ea
I've had a 3com etherlink III ISA, netgear fa311 PCI and a linksys 100tx PCI nics on my RH7.1 box ( a very old P166 ). No problems.
It is kind of curious about the dropped packets.
Have you tried command " # ipchains -L "
That should tell you of any denys you on the interface. ipchains rules work very much like cisco access lists. It still sounds to me like some sort of packet/protocol filtering.
Of course, I could be way out in left field on this one
hth
ea
Linux supports most NICs. This 3COM was the first fairly popular NIC that I've seen rejected by Linux or *BSD (the others were very old, no-name ISA NICs).
Ipchains rules are a possible cause of doctorcisco's problem, but since none were setup during the installation this is unlikely. | |
| doctorcisco 2001-10-22, 1:11 pm |
| quote:
Originally posted by ccieToBe
Linux supports most NICs. This 3COM was the first fairly popular NIC that I've seen rejected by Linux or *BSD (the others were very old, no-name ISA NICs).
Ipchains rules are a possible cause of doctorcisco's problem, but since none were setup during the installation this is unlikely.
I did check ipchains -L; there are no rules at all in there. Please don't tell me this thing does an implicit deny like Cisco!
doc | |
| ccieToBe 2001-10-22, 2:26 pm |
| quote:
Originally posted by doctorcisco
I did check ipchains -L; there are no rules at all in there. Please don't tell me this thing does an implicit deny like Cisco!
doc
Hehe, who knows. Seriously though, if there were an implicit deny you would see it. | |
| doctorcisco 2001-10-25, 2:31 pm |
| Well, I did go ahead and buy a PCI NIC. I even reinstalled RH (because I am too newbie and messed the machine up trying to configure the new NIC in place of the old one.) Now I can ping the box (WOOHOO!!).
However, I can't telnet the box. Isn't in.telnetd running by default on the server install? Sheesh!
Off to download an ssh client,
doc | |
| ccieToBe 2001-10-25, 2:46 pm |
| quote:
Originally posted by doctorcisco
Well, I did go ahead and buy a PCI NIC. I even reinstalled RH (because I am too newbie and messed the machine up trying to configure the new NIC in place of the old one.) Now I can ping the box (WOOHOO!!).
However, I can't telnet the box. Isn't in.telnetd running by default on the server install? Sheesh!
Off to download an ssh client,
doc
Most distros disable telnet by default for security reasons (telnet sessions are easy to hijack and older versions of th daemon can be DOSed). There's really not much reason to telnet into *nix boxes when you have SSH. It's great to hear that you finally got a NIC working. | |
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| quote:
Originally posted by doctorcisco
Well, I did go ahead and buy a PCI NIC. ........... Now I can ping the box (WOOHOO!!).
doc
Excellent ! ! |
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