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Digiboard Serial Ports on Linux Servers

Recently I have been working on a RedHat server installing all manner of stuff including serial ports. This customer has an 56K DDS line under contract for a few more years so we went with a Digi C/X controller to match what was in their SCO server. When I asked Digi tech support about a couple of things that weren't clear they suggested that I forget the the software and epca drivers that came with the controller and instead download and install their dgap drivers which comes with their familiar mpi software for configuring the board

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Printer Haikus  
- I knew this fine workhorse was not meant to be ignominiously put out to pasture. I gassed up the van and came to it's rescue. -

Domain values  
- A few years ago one of my customers forgot to renew their domain name registration. Of course it was poached and when they discovered their website was gone they called me in a panic. I poked around on the internet and found who owned the domain currently and called - $750.00 was the asking price. My customer thought it was an outrage and in a fit of pique we stopped pussy footing around, hyphenated their corporate name, registered a new domain and moved on. -

Load Balancing  
- Large web sites need to be able to handle a huge number of requests - often more than a single web server can handle. -

Dynamic BBx configuration  
- Since we have no way of knowing in advance what the tty number will be when she logs in we build a custom BBx config fle when she logs in. -

clever bash tricks  
- One thing that has always bothered me is having to type in long pathnames. I guess I should have read the documentation since there is indeed a better way -

Google Maps Beta  
- This app is surprisingly fast and has obvious features other map servers lack. The first thing I did was type in Boston, MA which is pretty close to home. -

More ssh ideas  
- A friend recently got 'rooted'. He was using ssh (not ssh2). He was getting pages on his phone and processes were dying and such, so he installed "chkrootkit" which is a program that checks your system to see if there is any of a number of root kits installed. He had SuckIt installed on his machine and now has a server to rebuild. -

More on self-modifying code  
- I first heard of self modifying programs years ago - it was frowned upon - but back then I was programming commercial applications. Then someone showed me Life, which was an interesting bit of interesting bits, but I soon lost interest. -

Assigning terminals in BBX config.bbx  
- Because pseudo tty numbers are assigned on a first-come first-served basis it can be difficult to assign the users the same 'terminal number' each time they log in . Here is a nifty way to tame those pesky tty numbers and get them to settle down. -

Debugging Facetwin Remote Printing Connections  
- I got a call today from one of my customers complaining that their remote printer was no longer printing. 'What changed?', I asked. 'Nothing at all!', she replied in her charming southern drawl, 'It just stopped printing!'. -

Installing Fedora Core 2 without a bootable CDROM drive  
- The other day I got my hands on an old Pentium 90 server. It's an old machine but so well made I still really like it. Anyways It had an install of Caldera OpenLinux on it, which ran quite well, but that I wanted to try Fedora Core 2. I ordered up some CDROMs which arrived in due course so I slapped Disc 1/4 Install in the CDROM drive and looked around for a bootable image which wasn't too hard to find as it was in /images. Curious though that the size of the image was 6,291,456 bytes - far larger than any floppy I ever saw! How was I going to solve this little dilemma? -

Digiboard Serial Ports on Linux Servers  
- This customer has an 56K DDS line under contract for a few more years so we went with a Digi C/X controller to match what was in their SCO server. -

Using the spooler to print to email  
- First define a new spooler destination using the dumb interface script and /dev/null for the device. Give your new spooler destination a name - I called mine email displaying a deficit of imagination. Next, change directory to /usr/spool/lp/admins/lp/interfaces and edit email if that's what you called it. I use and like vi for editing but you can use whatever editor you like. Finally, I added a line, changing the FILTER to get the emailing done. -

More using the spooler to print to email: email attachments  
- We already know how to modify a spooler interface script to email plain text to people, but it bothered me that print jobs with embedded PCL commands or other escape codes might get mangled in the emailing process. -

Maintaining / Phreaking modems lines using ANAC numbers  
- I remembered that I talked to one lineman who had a number he called and an electronic voice would repeat back the telephone number that he had called from. After twenty minutes of googling I found that what I wanted was called an ANAC (Automatic Number Announcement Circuit) number. -

A simple script for adding SCO users  
- One day I was adding a user to my customers system - I must have been tired - I had forgotten one of the steps and had wasted about an hour figuring it out. Frustrated, I muttered to myself 'There *must* be a better way!'. -

Cool Tools: Network View - a network node discovery tool   2012/04/13 AlVidetto
- Identifying addresses and open ports on a network, network node discovery tool. I'm not the only one who maintains this company's network. The operations guy is pretty capable and doesn't mind setting up PCs - he enjoys it. Well, between me and him we had lost track of PC, printers, WAPs, routers, more routers and such like that. We needed a network discovery tool and we found a great one by Michael Welschenbach at http://www.networkview.com/. -

Some common Unix network ports on my server and what they mean  
- One of the rules of thumb for system security is to turn off the ports you don't need. It had never really concerned me, as my Unix box is behind a router and the router doesn't forward any ports except for a couple I have specifically allowed. -

Troubleshooting network connections with arp  
- Identifying systems by mac address. MAC address ranges are assigned by the IEEE to electronics manufacturers to ensure that MAC addresses are globally unique. -


Do as I say! (and not as I do)  
- There it started, so innocently, so subtly but wires and mess go together as surely as yellow dogs and pickup trucks.` -

Protecting corporate email by using multiple anti-virus scanners  
- Anti-virus scanning is a critical part of protecting the corporate LAN -

Using rsync to update laptop  
- rsync lets you update a remote machine (eg, laptop) with another machine (eg RedHat server). We now had all the bits of the puzzle in place. Each laptop would connect to the Local Area Network (LAN) and we would use rsync to update the data directory on the laptop. -

Telephone Switch Considered Harmful  
- I arrived on site with a pair of routers to set up a bridge, but I wasn't getting anything from the CSU/DSU. The telephone provider started asking me all sorts of questions about the circuit such as framing, line code and clock source. After quite some discussion back and forth I impressed upon these folks that these question are properly asked of the circuit provider. -

A simple remote site monitor (part two)  
- The first thing I noticed is that sometimes all the sites I was checking were reported at once. I would get a string of messages and then things would be calm again. Clearly my own connection was having occasional drop outs rather than mailstarusa.com or my client sites. I reasoned that I would report outages only if machines I knew to be highly reliable were available. That is, if I could not ping certain DNS servers then I could safely keep quiet about the rest. -

A simple remote site monitor (part one)  
- decided that the thing to do was to monitor their IP adress for a while and see how many droputs they had. I searched the net and found many monitors, some of them very nice, but what I wanted was something very simple that would record the events in a log file. There didn't seem to be much but I did come across pingchecker. Pingchecker seemed simple enough for me, so I pasted it into a file and modified it to check my clients site. -

Telnetting to a port other than 23  
- A quick check proved I could telnet to either router. What I really wanted to do though, was to have the remote site telnet to the SCO system at the local site. Since I also wanted to be able to have the DSL providers telnet to the routers for maintenance, port 23 (telnet) was unavailable to me. -

Transferring Data from an Old Hard Drive  
- The machine I had installed in 1993 had developed a problem with the hard disk controller. I checked with the manufacturer and they had never even heard of EISA SCSI controllers. -

Adding a Hard Drive to Linux  
- Quick reminder of how to manually configure a second IDE hard drive on most Linux systems. -

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