Best of Technical Support
Our experts answer your technical questions.
Can I use an internal PCI modem with Linux? I have been looking all over the web and have found no documents about this. —Luis David Cardenas, email@example.com
The answer will depend upon which kind of modem you have (Plug-n-Play, winmodem etc.). If your modem has these switches (also called jumpers), configure it to use an IRQ/Com (IRQ3, Com 2 for example) and simply create a link (as root) to it:
cd /dev ls -s /dev/cuaX /dev/modem
where the X is directly related to the Com port you have chosen (Com1 = cua0, Com2 = cua1 and so on). If your modem is Plug-n-Play, you will have to create an /etc/isapnp.conf file and configure it accordingly. —Mario Bittencourt, firstname.lastname@example.org
Internet Connection Broken
I recently upgraded from Red Hat 5.1 to 5.2 and was surprised to see that my Internet connection no longer works. I set up my PPP connection through Network Configurator. I have no problem dialing and logging in, but when I pinged one of the sites, e.g., www.idl.net.au, I got this message:
ping: unknown host www.idl.net.au
Which is strange, because it used to work under 5.1. —Genesis Elliott, email@example.com
I suppose your ping is just a test and other things that used to work also stopped working (I am saying that because DNS might not be working, or the host you are pinging could have disappeared—I have seen that happen). Let’s suppose your problem is truly linked to the upgrade. Make sure that /etc/resolv.conf still has correct values (netstat -nr; ifconfig), or else make sure you cannot ping hosts by their IP addresses (rather than host name). Then, if that fails, under interfaces/ppp/communication check the debug box, and do a tail -f /var/log/messages. Bring the connection up, and the messages from syslog in /var/log/messages should give you a clue as to what is wrong. —Marc Merlin firstname.lastname@example.org
Chinese Big-5 Display
How do I display a Chinese charactered document under xterm and web browser? —Chi-Chih Chen, email@example.com
You can use cxterm to display Kanji under Linux, and it offers several ways to input Chinese. Netscape can also be configured to display Mandarin in the View/Encoding menu, both simplified Big5 encoded Kanji and traditional Kanji as used in Taiwan.
You should read the Chinese Linux HOWTO at www.phys.ntu.edu.tw/~cwhuang/pub/trans/linux-howto/Chinese-HOWTO-3.html (it has a link to cxterm). —Marc Merlin, firstname.lastname@example.org
Options at Compile Time
I know how to compile a new kernel and pick support for various options. Is there a way to do a sort of reverse lookup to find out which options were picked at compile time? This is needed in order to determine which options were compiled into a particular kernel I have floating around but for which I don’t have the accompanying config file. —Ian Gilchrist, email@example.com
This information is not saved as any type of text data specifically, but if you are creative you can find other ways to get this information. Each time Linux is compiled, a map file is also created. It contains the function names in the kernel, and with some work, you can probably figure out from there what you need to know.
It is a good idea to save the .config file with each compiled kernel. It has all the information you need; I often compress it with gzip and save it in the directory where I store my kernels. This is much handier than you may think. There is nothing worse than trying to compile a kernel for a two-year-old system with a really old LAN or SCSI card, when you cannot remember how you got it to work the first time. —Chad Robinson, firstname.lastname@example.org
Accessing Home Pages via FTP
We are a small ISP and have used Windows NT, WebTEN and MachTEN for our services. We have now changed to Linux.
We have set up Linux, and we want our customers to be able to use ftp to put their home pages on the server. This works fine, but they also are able to go up the tree to see the /home/dir, and even more, the whole hard drive. I want to change it so that they can go into their /home/$USER and no further. I have tried to use the guestgroup option in /etc/ftpaccess to no avail.
How do I do it? What is the proper syntax? Can anyone send me a working line out of the /etc/ftpaccess and the /etc/passwd file? —A.H.J. Mittendorff, email@example.com
The easier way is to create an FTP group (let’s call it ftponly) in /etc/group and change your creation script to add the users with this group. Then edit your /etc/ftpaccess and add guestgroup ftponly. Now, if you try to log on using ftp, you should be able to see only your directory. Note that since FTP will chroot to the user’s directory, you will also have to add a /bin directory with a statically linked ls version.
Also, check that your /etc/ined.conf has a line like this:
ftp stream tcp nowait root /usr/sbin/tcpd in.ftpd -l -a
—Mario Bittencourt, firstname.lastname@example.org
Setting Up kermit
I have searched through all of the suggested resources and have been unable to find an answer. How can I set up kermit or Linux so that they can talk to each other? I am trying to use ckermit 6.0.192 to dial a pager, and I get the message “Warning: terminal type unknown …” each time I start up kermit.
Once I get to kermit and try to dial a number, I get the error message “unable to initialize modem”. I have used minicom to dial my modem and it works fine, but the application (Big Brother) which uses the modem is set up to use kermit. —John Willoughby, email@example.com
Try to force the TERM variable to vt100 before starting kermit:
At the kermit prompt, try this sequence (I am assuming /dev/modem is a correct link to your modem device):
set line /dev/modem set speed 57600 connect atdt...
This works fine for me. —Pierre Ficheux, firstname.lastname@example.org
I am a newbie at installing Linux so I am not quite sure what I may be doing wrong. Here is my problem:
I am trying to install Red Hat on my machine, which currently has Windows 95 on it. I have a 6.4GB hard drive and I have used Partition Magic to free up about 2GB of space. Windows 95 is on three partitions; one of those is an extended partition. I decided to use Disk Druid to make the Linux partitions because I am not totally familiar with fdisk. I first made a root partition, which worked fine, but if I try to create any other partitions, I get an error with unallocated partitions and the reason is “no free primary”.
I don’t really want to format my hard drive, but if it comes to that, so be it. —Ben Barth, email@example.com
You may only have four primary partitions on your hard drive. If you need more, you can make an extended partition instead of a primary. Under DOS, this is how logical drives are created. Linux has no problem residing on an extended partition, so you should be able to install it once you create the extended partition. Remember that you will probably want to make two: one for the file system and one for the swap space (usually about twice your system RAM in size). —Chad Robinson, firstname.lastname@example.org
Getting Started with Applications
How do I run a new application or install it into X? For instance, my Red Hat bundle had a CD with lots of software on it. I used RPM to install Word Perfect 7.0. Now I have an /opt directory with a /wp70 directory under it and a bunch of subdirectories under it. Which one is the executable? What magic word or process am I missing to make WP run? All the files seem to be there. This is the first question I haven’t figured out, and I have spent a lot of time trying. My system is working great but this is just too nebulous for me. —Sean Wyatt, email@example.com
Usually, applications that install in /opt install a link to their binary in /opt/bin. So, all you should need to do is put /opt/bin in your PATH. In the /etc/profile file, you can add:
PATH=/opt/bin:$PATH export PATH
Should the executable be absent from /opt/bin, you can locate it using:
find /opt/bin -follow -type f -perm -700
then create a link yourself and add whichever directory it lies in, to your PATH. —Marc Merlin, firstname.lastname@example.org
After recompiling the kernel, I get a message along the lines of:
modprobe: cannot find net-pf-4 modprobe: cannot find net-pf-5
at various times. It does not seem to affect the behavior of the system, but I would like to know what it means and what I should do about it. —Frank McCabe, email@example.com
net-pf-4 and net-pf-5 refer to support for IPX and AppleTalk, respectively. You can avoid the modprobe messages from appearing at boot time by including aliases for each in /etc/modules.conf (or /etc/conf.modules), i.e., add these lines to the file if they are not already there:
alias net-pf-4 off alias net-pf-5 off
Most of this information can be found in /usr/src/linux/Documentation and I would recommend becoming familiar with the resources in this directory. Note: /usr/src/linux is just a symbolic link to your current source tree of the Linux kernel. —Andy Bradford, firstname.lastname@example.org