APLawrence.com -  Resources for Unix and Linux Systems, Bloggers and the self-employed

LDAP Basics

If you are running Linux, LDAP is almost certainly installed. SCO's OSR5 products don't include LDAP. However, Skunkware does have an OSR5 LDAP server, and you can install it and learn LDAP basics in literally just a few minutes: LDAP is not at all difficult, and anyone capable of basic scripting can understand it and use it.

Title Last Comment
Is there a way to get Ethernet from Wireless?  
- Is there a way to get Ethernet from Wireless? My landlord gives me free wireless but I need to plug my Vonage phone into Ethernet. -

Why use a VPN instead of opening ports?  
- I need to access my security cameras from home. My camera guys says we need to forward ports on the firewall, but my firewall guy says I should use the VPN instead -

Google's QUIC may speed up the Internet  
- Speed is very important to Google. TCP connections have too much overhead and plain UDP is too unreliable. QUIC bridges the gap. -

Amazon Echo   2015/02/07 TonyLawrence
- Amazon Echo has become my new best friend, especially in the early morning when I get my weather, news updates and then start exercising to music. -

Amazon Echo   2014/11/09 mikegauley
- Amazon Echo - great idea or dud? I'm about to find out as I have ordered one. My daughter thinks I'm nuts, but I think we will like this. -

802.11g/n High Gain USB Wireless G / N Long-Range WiFi Network Adapter  
- Boosting the very weak free wireless signal at our vacation home isn't easy -

Why use private network addresses  
- I still see systems where people have used public ip addresses for private networks. -

Overview of Visionfs On SCO Unix   2014/05/20 Mark
- If you find yourelf in the unfortunate position of having to use Visionfs on older SCO, here are some things to know. -

All about Telnet  
- A collection of telnet related information and links. Telnet is seldom used today except for network troubleshooting. -

Wireshark 101   2013/05/27 TonyLawrence
- Silly me. I really should have started using Wireshark long before this! -

Auto Edge archive removal script  
- The way I wanted Edge to work, was just like the days when we backed up to Tape. We would pull Master backups each night, label the tapes M-F, and take a SAT tape off-site for an extra layer of protection. When Monday rolled around, the new backup would replace the old Monday backup, rinse, lather, repeat. This changed when we upgraded to Edge 3.x, and started using the NAS. Once we had multiple servers with multiple jobs backing up to the same resource, and not having enough free space on the NAS because backups were piling up, I had to resort to manually deleting things (through edgemenu) on the NAS to free up space. This got old rather quickly, as I had to look down the long list of backup jobs, and determine which ones could be deleted. If I missed one day, the NAS would fill up, and backups would fail. -

Basic Home Networking, Part 3, File and Printer Sharing  
- The point of a computer network is sharing. You might not be sharing much, perhaps even only the Internet connection. If that's the end of it, you don't need much more than part one of this series, which deals with the setup of a basic small network. -

Basic Home Networking - Part 2, wireless setup  
- Often all that needs to be done is to tell your computer that you want to connect to a wireless network. It's not always that easy, but it certainly can be. However, even if it is that easy for you, you might still want to read the rest of this in case you have problems later. You also might want to read it because being "too easy" to get connected could mean that you are running some security risk and need to address that issue. -

Basic Home Networking - routers and switches   2011/08/16 BigDumbDinosaur
- Setting up a small office or home network used to be a fairly complicated task. Aside from the technical knowledge needed, there was expensive equipment to buy and specialized tools for wiring. That's all changed - the necessary equipment is cheap and readily available and it's all very easy to configu re. -

A non-technical guide to understanding and fixing TCP/IP problems on a network   2011/08/14 BigDumbDinosaur
- The title is a bit incorrect in the .non-technical. claim, because we are dealing with a geekish subject here and I can't avoid being a little "techie". -

- Early SCO Unix had no DHCP capability (it did have DHCP server). That perhaps was somewhat reasonable; these machines were servers and could be expected to have a static IP address. However, as DHCP can do much more than simply provide an IP address, having DHCP would have been advantageous at times. -

Mysterious Duplicate IP addresses   2011/04/20 TonyLawrence
- Proxyarp on smart switch causes sudden appearance of duplicate ip addresses: All machines on our 192.168.206.x subnet (mostly Mac's, with Windows servers) got the IP conflict message when they started up in the morning. We do have a linux dhcp server running on that subnet, but it only hands out 2 IP addresses for barcode guns, and those are given the IP based on their MAC address, so each barcode gun always gets the same IP and can move to other buildings without reconfiguring them, as they run in dhcp mode. -

A SCO Openserver to Red Hat Linux Conversion   2011/04/02 TonyLawrence
- A detailed history of a SCO to Linux Conversion - including desktop users. -

SOCAT - The most comprehensive networking utility  
- Socat relay for bidirectional data transfer between two independent data channel -

LOD Communications, Inc.
A Tale of Two Routers   2010/07/17 TonyLawrence
- Mistakes will always come back to bite you someday. DHCP subnetting malfeasance bit me. -

Simulate complex networks with qemu  
- Every qemu instance forms part of the host bridge and it will behave exactly like a computer attached to your switch/bridge. -

- I had to do server monitoring for one of my clients and I ended up using the sexy conky tool for it. But I had to do a lot of jugglery to make it work on the web. -

Paradigm ImagePRO Ci40m HD TCP/IP setup   2010/04/16 TonyLawrence
- Okey-dokey. I double checked all the bad cable, bad port, ip conflict stuff. Nothing wrong there. -

Network Troubleshooting   2010/03/16 AndrewSmallshaw
- As it turned out, the problem was very physical: a light fixture had fallen down and loosened some connections to a long forgotten ethernet switch. -

Lan sniffing with a DualComm port mirroring switch and Windump   2010/01/23 TonyLawrence
- Using Dualcomm Port Mirroring switch and Windump to trace network problems and detect virus activity. -

Fishing for an unknown device  
- If you have a DHCP server anywhere in the network, the device will have obtained an IP address. But what is it? -

Network Know-How  
- This is the book I'd give to someone who needed to learn a lot about computer networks, quickly. -

More routers used as switches  
- I got a good chuckle when he showed me the first printer. Only one network tap near where they put it so - he bought a router. -

A gentle routing tutorial  
- The Internet is held together by the layer III of the TCP/IP protocol suite. -

A primer on networking and routing topologies  
- We are going to look at how you can setup your home or office Linux box to do simple packet forwarding with static routes. -

(SCO Unix)Why is ftp transfer between two 100Mb machines so slow?  
- Usually this sort of thing is from bad (cheap) Nic cards and/or mis-negotiation with the switch or just lousy drivers. Ftp does a lot of work; junk affects it more than simple http, telnet or ssh connections. -

The amazing tool called netcat  
- netcat with its simple and yet incredibly powerful command line constructs has helped me innumerable times -

Peer to peer networking using bittorrent - technology and dynamics  
- Bittorrent technology is essential decentralization. It reduces server load and increases efficiency. -

An Unexpected IP  
- Windows, Linux, Mac OS X, it would have all been the same: An old server had an OS transplant and needed to be connected to the network. -

What is p2p?  
- The moment you hear the term p2p, the first thing that comes to your mind will mostly be BitTorrent. It is a fantastic file sharing protocol and in a way it rewrote the way we have always understood file transfers on the Internet. Curious geeks can refer to this detailed specification to understand how the protocol works. It is advanced technology and a brilliant way to solve the age old problem of scalability and web traffic overloads which have crashed the best of web servers. -

Basic (very basic) TCP/IP  
- I recently had to explain TCP/IP to a non-technical person. What follows is basically what I came up with, though it doesn't have any of the hand waving, pointing or any of the other dramatic gestures and facial expressions I used to fill in the gaps. -

Centos ssh failure  
- I have a customer who uses a fairly new Centos server to function as an ssh gateway to his ancient SCO box. On Friday he told me that no one could ssh in. -

CompTIA Network+ Study Guide  
- If you are trying to prepare for the CompTIA Network+ certification exam, or are even just wanting to learn networking from the ground up, this is your book. -

Dealing with Duplicate IP addresses   2011/11/13 TonyLawrence
- Duplicate IP's on a network is an interesting problem that has no completely satisfactory solution, especially when malicious intent is involved. Let's leave those intentional conditions for another day; here we'll look at what happens when an IP gets duped accidentally. -

Don't trust Web Designers  
- My apologies to those of you who are competent. I tend to remember the screwups and of course if things are done right, nobody calls me. But.. -

Blocking Unwanted Visitors  
- Blocking unwanted visitors by redirecting them into a molasses piti: something that won't resolve, thereby slowing him down. -

Multitech RF850 Linux Router  
- Multitech RF850 is a linux based router that is no longer manufactured. If you come across one, here's what you need to know. -

Network Subnets for Humans  
- Subnet selection affects people too. None of this matters at a technical level. It can just help avoid human mistakes and confusion. -

Does Verizon really think 15% packet loss is OK?  
- Customer with VPN issues battles Verizon - Verizon says a 15% packet loss in nothing to be concerned about! -

VMware Networks, Bridged vs. Nat vs. Host   2011/05/19 Firedancerx
- Understanding VMware networking options. By default, VMware works in "bridged" mode - you use the card by attaching a virtual network device to it. -

RTL8111/8168B PCI Express Gigabit Ethernet Failure   2011/10/16 anonymous
- Forcing driver with Realtek RTL8111 - an "lspci -vv" revealed that things were not right.. -

Linksys RV042 VPN  
- I'm a cheaprouter and you are goig to have an unhappy day if I have anything to say about it! -

The E-Myth Revisited  
- I got very sick of Sarah and her pies. First of all, it's mostly fluff. Something that you or I might say in three sentences turns into a long chapter here. -

Power failures and IP addresses  
- Why should a power failure have reset ip addresses? That printer definitely has a static address; so did the server. -

The Last Time I Climbed a Ladder   2012/07/11 TonyLawrence
- I'm getting too old to be climbing up shaky old ladders. I did it this time, but never again. -

Do-It-Yourself Linux  
- Difficulties of Using a Wireless Router with Linux - success with Linksys -

Samba Configs - six hours!  
- They told her it would require six hours of time AND 'training' to fix the Samba configuration! -

- Verizon said that they'd have the same IP, and the same type of T1, so all they had to do was unplug their router(s), move them, replug and all would be fine.. -

FTP Problem   2011/10/07 TonyLawrence
- Reasons ftp through firewall doesn't work - ports, active vs. passive and so on. -

Cables and switches basics  
- Basic Network Hardware Most networks use RJ45 connectors plugged in hubs or switches - usually switches today. -

Wrong DNS causes interesting glitch  
- An incorrect old DNS server in /etc/resolv.conf causes interesting behavior -

It doesn't work that way  
- Internal addresses like "192.168.6" are unrouteable private addresses - you can't get there from anywhere else on the internet. -

A Change of Address  
- The caller had a downed Unix machine. Big crash, dead hardware, but he had a backup machine that he had restored backups to and had changed the IP to match the old server -

The Book of Wireless, 2d Edition  
- Everything you ever need to know about Wirelss networking: I admire authors who cover their subjects completely yet remain readable. It's not easy to do that, but John Ross did so here. This is very complete coverage of wireless networking from all points of view. -

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