The Answer Guy 29: Network Cards

#### "Linux Gazette...making Linux just a little more fun!"

# The Answer Guy

#### By James T. Dennis, answerguy@ssc.com
Starshine Technical Services, http://www.starshine.org/

### Network Cards

From Greg on 04 May 1998
Hey there,
I recently purchased a copy of Redhat 5 and installed it on a system. My intentions for this system was for it to act as a proxy server and a mail server. I used a machine I had spare and installed. All of the devices detected but now I can't seem to get my network card to act. I checked the network settings in `netcfg` in xwindows but it said that the card was active. The card isn't responding (according to the lights) though. I have now tried two cards (3com 10/100 mb and a kingston 10 mb) and both have returned the same error on pinging an address (Network is unreachable.)

> Here's a synopsis of configuring a system for ethernet networking under Linux:
> load modules (if necessary)
>   They may be built directly into your kernel.
> `ifconfig $IF $IPADDR $NETMASK $BCAST`
>   If you get an error like:
>   `SIOCSIFADDR: No such device`
>   go back and load the correct driver or compile it into your kernel. If you still get that error it's probably an unsupported card --- or you're trying to use the wrong driver.
> `route add -net $NET $IF`
>   Add an entry to the kernel's routing table to associate your LAN with that interface.
> `route add default gw $ROUTER` (if necessary)
>   Add a route to point to your LAN's router to the "rest" of the world. Note, in some cases you might not define a default route. For example if your box is the router between your LAN and an ISP that you dial up with PPP or `diald`. (In that case the default route would be set by your `pppd` and `diald` packages whenever the link to your ISP became active).

Is there something else I have to initialise to get my cards to work or do you think it could be a conflict of sorts?

> When trying to troubleshoot networking problems the commands you want to beat on are:

> `ifconfig -a` | list all interfaces
> `route -n` | list all defined routes
> `ping` | try to reach various hosts
> `tcpdump -i $IF -vvv` | dump all activity occuring on an interface
> `traceroute` | watch how packets "try" to reach their destinations

> In this case you want to post the output of your '`ifconfig -a`' and '`route -n`' commands as well as the IP address and network/mask that you're attempting to use (for each interface).
> Note: since you mention that you're trying to configure this system as a proxy server it's important that you get each of of its interfaces working properly before attempting to use any routing, masquerading or proxying through it.
> What proxy package(s) are you trying to use?

Thanks
Greg!

> You're welcome.

##### Copyright © 1998, James T. Dennis
Published in Linux Gazette Issue 29 June 1998

versions | lilo | virtdom | kernel | winmodem | basicmail | betterbak
shadow | dell | dumbterm | whylinux | redhat | netcard | macrovir
newlook | tacacs | sendmail | dialdppp | ppp233 | msmail | procmail