Best of Technical Support
In Windows NT there is a command-line utility (ipconfig) that lets you see the current ip configuration. Is there a utility in Linux for this? —Skip Bigelow, email@example.com
Even though there are graphical tools to give the information you've asked (including Red Hat's netcfg command), you can always use /sbin/ifconfig. It will give you detailed information regarding all active interfaces (ethernet, ppp, loopback etc.). —Mario, firstname.lastname@example.org
I have been browsing many different Linux web sites to look for any FAQ or guide on this topic: How to share a cable modem connection at home between a Linux and a Windows machine, which is where the cable modem installed. I would appreciate it if you would give me some pointers. —Samuel Fung, email@example.com
I would move the cable modem to the Linux machine and share it with your other computers from there. Why? Because Windows has no provision, off the shelf, to serve as a router, enable security features such as packet filtering, masquerading, forwarding, etc., while Linux does all that quite naturally and quite well. You do not specify the cable modem you have, but I would suggest looking at http://www.linuxdoc.org/ for documents on networking and connecting network devices to your Linux box. After that, look at the how-to articles on connecting to an ISP. —Felipe Barousse, firstname.lastname@example.org
Is it possible to turn off the kernel boot-up messages? —Nicholas, email@example.com
The easiest way is to set console=ttyS3,38400n8, or something similar, on the LILO command line to redirect console output to a serial port. —Marc Merlin, firstname.lastname@example.org
When I tried to log in to my Linux box this morning, I was surprised to find out that I was no longer able to do this. The login prompt appears as usual, but when I type the user name and press Enter, instead of the password prompt a new login prompt appears. No messages appear except a line that says: /var/hackr0x/login: No such file or directory. This line disappears so quickly that I had to repeat the procedure of typing the user name a couple of times in order to decipher it. —Victor, email@example.com
Your machine was indeed compromised. At this point you don't want to fix your machine, you just want to get your data off and re-install it. You don't know what's been modified nor how. In cases where you can't log in at all, you can always boot with linux init=/bin/bash at the LILO prompt, and then do: mount -wno remount/mount -a /etc/rc.d/init.d/network start (if you want to back up data over the Net). You can also boot from a rescue floppy or CD. Once you get your machine re-installed, do not just connect it to the Internet again without securing it properly. Make sure you have all the updates installed; do not run any unnecesary dæmons, and firewall the machine if possible. —Marc Merlin, firstname.lastname@example.org
Every major distribution has an “announce” list for security updates. After you reinstall, get on the list for the distribution you run. Also, remove unused software—it's the cheapest, fastest security precaution you can take. —Don Marti, email@example.com
Nowadays I'm working with Linux firewalls, and I'm configuring one in a client organization. I found the following lines in the script that applies the rules of the firewall (IPCHAINS):
INT0="eth0" IP0="192.168.1.125/24" NET0="192.168.1.0"
What is “/24” in the IP number?
Also can I put two networks in the same variable? For example:
—Fabio Losnak, firstname.lastname@example.org
The “/24” in the IP number means the network 192.168.1.0 with a netmask of /24 or 255.255.255.0. You probably cannot put two networks in the same variable but that would really depend on the script that is parsing this. —Marc Merlin, email@example.com
As root, I cannot get rid of the following files; they should belong to the deb package r-base, but in this case they seem to be some kind of links:
pimento:/home/ottoz# ls -l /usr/lib/R/library/ts/latex/ ........ br-xr-srw- 1 25955 26473 116, 32 mar 20 1987 beavers.tex br-xrwSr-- 1 8301 31084 114, 32 ott 12 2021 sunspot.tex br-srw-rw- 1 29281 8302 116, 108 set 27 2031 ts.union.tex
I get a message like cannot unlink. operation not permitted —Odoardo Zecca, firstname.lastname@example.org
You had some file system corruption. chattr -i *.tex should remove the incorrectly set immutable flag and let you delete the files. —Marc Merlin, email@example.com
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
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With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide