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Network Administration

E.10 Network Administration

E.10.1 Linux isn't detecting my NE2000 compatible network card.

It has been found that some NE2000's that worked with earlier kernels, do not work with the later 2.0.X kernels. For some, the following work around will enable them to work.

You can try to get the card to work by doing this:

    insmod 8390
    insmod ne io=0xXXX irq=Y

(Note: Replace XXXX and Y with your IOAddress and IRQ. Most common values for th IOAddress are 0x300 and 0x310. The IRQ may be anything.)

After this, use ifconfig or netcfg to configure the card. Sometimes, even though the card is recognized, there have been reports of the card still failing to transfer TCP/IP packets. This is being looked into.

If the above works, add it to /etc/conf.modules. It should look something like this:

alias eth0 8390
alias eth0 ne
options eth0 io=0xXXX irq=Y

E.10.2 I have installed Linux, and it seems to initially start booting. However it gets down to something called sendmail and then the machine seems to hang. What is happening and what should I do?

If after the install the machine seems to hang when it reaches certain processes like sendmail, apache, or SMB there is probably a network problem. The most common cause is that Linux can not look up the name of the machine you have called the box (if you set up networking to have a machine name). The machine is currently paused waiting for the network timeout of DNS lookups, and will eventually bring up the login prompt. Login in as root and check the usual culprits for a problem.

If you are directly on a network with a DNS server, check the file /etc/resolv.conf has the correct values for your machines DNS server. Check with your systems administrator that the values are correct.

If you are using Linux on a network without a DNS server (or this box is going to be the DNS server :)), then you will need to edit the /etc/hosts file to have the hostname and IP address so that the lookups will occur correctly. The format of the /etc/hosts file is like the following example:

127.0.0.1               localhost localhost.localdomain
192.168.200.1           mymachine mymachine.mynetwork.net

Where the example machine is called mymachine.

E.10.3 I have upgraded to 5.0, and sendmail is no longer relaying email like it used to. What is going on?

Due to various email spammers using unknowing Red Hat boxes as email relayers and some other problems, we have turned this off by default in 5.0

You can add the names of systems that you want to be allowed to relay mail to the file
/etc/relay_allow. The web site
/urlhttp://www.informatik.uni-kiel.de/%7Eca/email/check.html
for more details on this.

If you are having problems with sites sending you UBE (Unsolicited Bulk Email), you can also deny them access to your machines with the new features of sendmail. Add the sites to the file /etc/mail/deny and then make a hash table for it.

The following command can be used to create the hash database version of this file:

makemap -v hash /etc/mail/deny < /etc/mail/deny

E.10.4 I have installed Linux, recompiled my kernel, and now I get errors when the network comes out about various net-pf modules not found. What is happening and what should I do?

This means that Linux was unable to find modules for various network protocols. The most common ones are net-pf-4 (IPX) and net-pf-5 (appletalk). It looks like that during a kernel recompile these were not included and some service is looking for it during the boot.

First check to see that you are not running a service that is wanting it (mars-nwe, netatalk, etc). If you are you will need to recompile the kernel with these items or turn off the service.

If you still get net-pf errors you can fix it by following these directions:

cd /etc
vi conf.modules

Add to the file:

        alias net-pf-3 off
        alias net-pf-4 off
        alias net-pf-5 off

This should turn off the messages upon boot as it tells linux that these are OFF and should not be looked for.

E.10.5 How can I configure my dialup PPP Internet connection?

These sites have excellent current PPP information..

http://www.redhat.com/support/docs/rhl/PPP-Tips/PPP-Tips.html
http://www.redhat.com/support/docs/rhl/Dialup-Tips/Dialup-Tips.html

In addition, The control-panel in X windows has a tool called netcfg that will allow configuration of your modem.

To configure PPP, via the control-panel bar:

The [email protected] is also useful.

E.10.6 How can I allow non root users to start ppp connections?

Have netcfg setup ppp for non-root users. Then as the non-root user use the command

/usr/sbin/usernetctl ifcfg-ppp0 up

E.10.7 My system keeps losing its network routing information.

The problem that you are describing may be due to the fact that the gated program is running on your system. In a proper configuration it will bring interfaces up and down when needed. Unless you have configured its startup scripts and are running a router, it should be disabled (we are sorry it was shipped enabled, and future versions will not have it enabled.) To turn off gated, please do the following:

/usr/sbin/ntsysv

disable gated

quit ntsysv

Then, for best consideration, please reboot as gated may have left the network in a bad condition. If that is not possible, please do the following

/etc/rc.d/init.d/gated stop
/etc/rc.d/init.d/network restart


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