Best of Technical Support
I have a mail server (RH 6.2, Sendmail Single Switch) acting as a smart relay on our DMZ. Internally, we have a mail server (RH 7.0, Sendmail Single Switch) that acts as both an SMTP and POP3 server.
We need to be able to differentiate between local-only and WAN e-mail accounts. Local-only accounts would be limited to local delivery/receipt and WAN accounts would be granted access to the world for inbound and outbound mail.
To further complicate matters, all users should have the format of firstname.lastname@example.org for e-mail addresses. Is there a method of doing this within the capabilities of Sendmail or, if not, what package(s) will allow me to do this? —Michael Phillips, email@example.com
There are many approaches to solve your riddle. For instance, an easy one would be to restrict e-mail relaying with the /etc/mail/access file on an client IP address basis. Your actual request is not a complex one, you just need a bit of a planning on your network layout, the addressing scheme and a bit of tuning on the Sendmail side. Go to the http://www.sendmail.org/ site and look for all relaying-related documents. That will help you solve your requirements. —Felipe Barousse, firstname.lastname@example.org
Is there a Telnet time-out setting on Linux? My sessions time out after about five minutes. —Jan Dubroca, email@example.com
You are probably Telneting outside of your network, through an IP masquerading server that times out TCP connections after five minutes. On Linux, the fix for this (on the firewall) is:
# Fix the masquerading timeouts # tcp tcpfin udp ipchains -M -S 86400 60 120
—Marc Merlin, firstname.lastname@example.org
I don't believe that there is a tim-eout setting for Telnet. I assume that what's timing out is your shell. The shell time-out can be set in /etc/profile. My guess is you've got an entry that looks something like this:
The value here is in seconds. You can change this to give yourself more time or simply remove the line to disable shell time-out completely. —Paul Christensen, email@example.com
I used Red Hat 6.0 to install Linux. I booted the machine from CD-ROM successfully, and I pressed Enter after boot: This message appeared:
Loading initrd.img..................... Loading vmlinuz........
Then the computer stopped.
When I booted my computer from the floppy disk (Win98 bootdisk), I ran the /dosutils/autoboot from the Red Hat CD-ROM. Unexpected, it appeared that I had installed Linux successfully and even configured the X Windows System well. In the end, the computer told me:
Congratulations, you have installed linux successfully,...... The system reboot....
And when it rebooted, this message appeared:
Loading linux..........Then the computer stopped again.
I have also tried Red Hat 5.0, Bluepoint1.0 and 2.0, TurboLinux, Slackware. The results were all the same. WHY? —ekun, firstname.lastname@example.org
Apparently, you can boot Linux from loadlin (which you did when you started the Linux install from Windows), but, for some unknown reason, it fails when you boot with LILO. One option is to do an install from Windows, like you already did, and then boot from the RH rescue CD-ROM. Copy your kernel (in/boot) to the Windows partition (which you will need to mount too). Copy and configure loadlin (you should have them on your RH CD-ROM), and use loadlin to boot Linux. A sample loadlin config from my system looks like this:
moremagic:/drv/c$ cat linux.bat c:\linux\loadlin\loadlin @c:\linux\loadlin\boot moremagic:/drv/c$ cat linux/loadlin/boot c:\linux\loadlin\vmlinuz root=/dev/sda6 ro
—Marc Merlin, email@example.com
I've seen this happen as the result of booting a kernel that's optimized for the wrong processor, but if this is happening right away after a fresh install (in fact, after EVERY install of any of a number of distributions) you most likely have a serious hardware problem. You should try different RAM if you have any available. I can't say for sure that the RAM is the culprit, but that's where I'd start. —Robert Connoy, firstname.lastname@example.org
I have installed an IDE Atapi Zip drive and need to know how to have Linux to find it. I have tried to recompile but get the following error:
Makefile Makefile: 213 arch/i386/Makefile: No such file or directory Makefile: 481 Rule make: No such file or directory make *** No rule to make target Rules.make. Stop
—Bob Parry, email@example.com
Did you read README in /usr/src/linux? You compile a kernel like this:
make menuconfig; make clean; make dep; make install; make modules; make modules_install
More details can also be found here: www.linux.com/howto/Kernel-HOWTO.html. If you already have the right module compiled, modprobe ide-floppy should do the trick. —Marc Merlin, firstname.lastname@example.org
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.
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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