configuring multiple NICs

[spensah]

I've got a problem getting my UNIX box to respond to requests from users on the Internet. The box has one NIC with an internal IP address for in-house comm and another NIC w/ a public IP address for users to acccess it with a Telnet session over the Internet. When in-house and I ping the public IP address, I get a normal response, but when I ping it while using a dial-up connection through my ISP, I get no response. The box's link to the outside world is a DSL modem that acts purely as a bridge, and the DSL modem is then hooked up to a hub, and the UNIX box is hooked up to that hub as well. I've also got a LinkSys router hooked into the hub, which router serves as the gateway to the outside world for the internal network. If I telnet the public IP address from within our internal network, I can do it successfully. But when I do it from the Internet, no dice! Do any of you have an idea what could be going on?

 

[apeasecpc]

It sounds like a routing problem between the public Internet and the UNIX box.

Are you able to get out to the internet from the UNIX box? Your being able to ping the UNIX box's "public" IP address from within your network does not mean it is actually visible to the public internet.

The LAN side of the DSL modem and the "public" side of the UNIX box both need to be on the same subnet.

Also your ISP for the DSL needs to recognize your DSL modem's public IP address as the gateway to your UNIX box's public IP address.


On a side note, are you using any kind of encryption or security for your connections over the internet.

 

[spensah]

I was told by our ISP that the DSL modem is acting strictly as a bridge and therefore does not have an IP address. I have not dealt with this long enough to confirm or deny that, but I had the same impression about it being a routing problem. However, we actually have another public ip address that we've used and have tried changing them (between our router and unix box) and we've been able to get to the router to regardless of the ip address and NOT been able to get to the unix box regardless of the ip address. So that makes me think that something is wrong with our configuration on the unix box so that the NIC with the public ip address is not working. Are there certain files that need to be modified in order for the NICs to work in tandem? Let me know what you think. Thanks!

 

[fredericofonseca]

More details please.

1- DSL modem make/model.
2- Number of IP's given by the ISP to you
3- Default gateway given by ISP
3- Output of netstat -r and ifconfig -a
(change your public IP'S before posting them here!!)

Once we have this we may be able to give some more help or ask more questions regarding (1).




Regards

Frederico Fonseca
SysSoft Integrated Ltd

http://www.syssoft-int.com

 

[spensah]

Frederico-

E-mail butch@alpinesupply.com and I'll supply you the information.

Thanks!

 

[apeasecpc]

It is doubtful that the problem is with the NIC setup if you are able to ping the NIC from within your network.

Have you confirmed that your internet gateway address, router, and unix box public IP address are all on the same subnet? If the netmask is wrong, or an IP address is beyond the range of the netmask it will not work.

Are you able to get out to the internet from the UNIX box?


I understand your reservations about posting your exact addresses here, but if you mask the portions of the addresses that are the same, you should be able to provide enough information here for someone to be able to help you:

For example posting something like the following is not going to give away your addresses, but allows someone to sort out whether there is a subnet problem...

UNIX Public IP address is xxx.xxx.xxx.313
Router is xxx.xxx.xxx.315
Gateway is xxx.xxx.xxx.311
Subnet mask is 255.255.255.000

 

[fredericofonseca]

Here is the info spensah gave me.

ifconfig -a
net1: 10.1.1.xxx netmask 255.255.255.0
net0 aa.bb.cc.98 netmask 255.255.0 broadcast aa.bb.cc.255



netstat -r
Routing tables
Destination Gateway flags refs use interface
default aa.bb.cc.110 ugs 2 9364 net0
10.1.1 compab uc 1 0 net1
compab localhost ughs 4 36 lo0
aa.bb.cc compab uc 1 0 net0
compab localhost ughs 0 0 lo0
localhost localhost uh 5 9440 lo0
224 compab ucs 0 0 net1

The default gateway given by the ISP was aa.bb.cc.1


I may be wrong, but the above does not seem correct. For one it should not be .110, but .1, and the aa.bb.cc -> compab doesn't either.

Note that the router mentioned by spensah should have the second IP supplied by the ISP, and should have as a default gateway aa.bb.cc.1, and does not affect the Unix machine.




Regards

Frederico Fonseca
SysSoft Integrated Ltd

http://www.syssoft-int.com

 

[spensah]

I can not get out ont the unix box.
I will try changing the gateway to .1 and will advise.
spensah

 

[spensah]

I changed the address of the default gateway to the .1 and everything is working now. Thanks for your help!

 

[spensah]

I changed the address of the default gateway to the .1 and everything is working now. Thanks for your help!