Archive: Networking

For quite some time I've been making use of a dd-wrt modified linksys box on my home network as an openvpn endpoint so that when I'm out and about in the world, I connect the vpn, switch firefox to r…

I've had a couple of small wireless projects lately and have really been having a great time playing around with the Linksys-Cisco WRT54GL Wireless-G Broadband Router and one of the many GREAT 3rd pa…

First, I guess I should give a primer, what's an RBL? RBL stands for Realtime Black List (or Realtime Block List depending on who you talk to.) The idea is there are machines that either 1) have no b…

I've got a home project to run more network cable here lately and found techtoolsupply to be an interesting resource for network and other cabling supplies. I don't recall who I ordered from last tim…

I thought this writeup was interesting on the idea of using a web interface to customize a livecd. I've built a couple livecd's (that I still use) for tech support, but I'm always thinking of one mor…

I found this link of plugins for wordpress to aid in multilingual site building. I've been experimenting with English/Spanish designs of one site I maintain using plain html (index.html.en index.html…

How many times have I seen the same chain email about who knows what... it always ends in something along the lines of "I don't know if this is true, but I figure I don't have anything to lose, so pa…

Of course, we've heard of skype, vonage, and our dsl/cable providers hawking VOIP. I thought I'd make a note of this one though as the name is a bit more obscure... packet8

I would dare say there are more than a couple people "out there" right now that are puzzled as to WHY some of their mail is bouncing back to them as being rejected. Right now I'm talking about Bellso…

Why do I always wind up being the one to discover problems? .... Today in checking mail I found a mail that had bounced back from one of my clients that uses bellsouth... Now bellsouth has recently b…

As long as there have been wireless networks there have been people trying to squeeze out just a bit more range... there was the cantenna and now there are other variations on trying to collect and i…

For a while dnsstuff.com has been my favorite dns tools web site, but there are others. Recently I was pointed to domaintools.com.

There are lot's of ways to get a file from one place to another, emailing is the first that many think of. (For larger files I'll usually just upload to a directory on the website and then email a li…

http://www.zeroshell.net/eng/ is an interesting bundle of linux designed to be an out of the box network service swiss army knife of sorts. Here are the network services that it provides.... Kerberos…

There are some tools that I make use of almost daily. Either because something strikes my curiousity or because of necessity to find out a bit more about a computer issue. DNS lookup tools fall into …

In the US and Europe and many more developed parts of the world we take our internet connectivity these days for granted. (And some go into panic attacks when it's not available...) In some parts of …

I found a peculiar problem while I was setting up an openvpn link the other day. The goal was a simple shared key setup and I started with the sample configuration and modified it a bit to fit the ci…

A long time ago I had found how easy it was to reject messages outright with Postfix that came from non-existent domains. You know... junk from asdflkjuasdlfkjh@imadethisupmyselfanditsnotregisteredan…

I almost forgot to pass along a link to a more comprehensive detailing of postfix's anti-uce controls.... here. Also, in the last article I briefly mentioned whitelisting. IF you intend to have sever…

A few days ago I had reason to investigate iscsi and AoE (ata over ethernet). Both are protocols for sharing a physical drive over the network at the block level. Let me put it in context first. Trad…

One of the tools I looked at having for my expanding kit has been a usb wireless adapter that would work with minimal install on Windows/Mac or Linux. As you can imagine.... it's not as straightforwa…

I've noticed several times in the last week a server of mine that is using postfix has rejected messages due to a failure in the lookup at relays.ordb.org. At first, I thought this was just a false p…

I saw this a few weeks back and think it's a good idea. Essentially why don't we have a .bank domain registration and limit it to just financial institutions the way .gov is limited to government reg…

There's no better way to say it, netcat is SOO useful, and there is an encrypted variation... cryptcat, you can do quite a few interesting and useful things VERY easily with these two utilities. (*It…

I haven't been overwhelmed with VMware server's web interface. You can start a virtual machine, or see statistics, but you can't create virtual machines. Well, from the VMWare forums I did find a cou…

I like nx server and client, it can really make good use of low bandwidth connections to get a gui link. But, by default it's quick and easy to setup gnome and kde login sessions within nxclient, but…

ah... the joys of *nix utilities.... I've just successfully tested a "capture" of a live, running system into a virtual disk image. No, I don't mean that I booted up with an imaging utility. I took a…

I remember the question from long ago, we had just shared a printer across a windows network and.... wait for it.... "oh, well could I share my scanner too?" On windows the typical answer was NO, at …

As I mentioned earlier, Bellsouth seemed to be in the midst of a big DNS meltdown when I got up this morning. I spent some time getting various bellsouth customers "worked around" the issue by settin…

This morning, I'm noticing some of the machines I monitor having big DNS problems. It seems to be Bellsouth.net's dns servers gone sideways - none seem to respond. On one network in particular we're …

Vmware has launched a tool (windows only it seems) aimed to convert a REAL running system into a virtual machine. (For use with VMWare's virtualization products. The converter also can convert images…

I've seen skype I just haven't used it personally until very recently. In fact there was a place (dialpad?) that I had used once upon a time for a few free long distance calls online. It was neat, bu…

This was weird and now that the switch is replaced I haven't been able to duplicate it, but let me explain. There was a netgear fs608 (8 port unmanaged) switch plugged into a linksys router (model nu…

Incidents.org has been running their security tip a day this month and I really liked this one. It's essentially a way to encrypt your wireless traffic using ssh. That's something I've covered here b…

The other day I was struggling with something that should have worked "out of the box". It was a little wireless bridge (Linksys WET54G Wireless-G Ethernet Bridge). The idea was to just connect it to…

The new Docsis 3.0 standard has been finalized and it allows for 160Mbps or more downstream and 120Mbps upstream. It also will support IPv6. Of course, in order to support those speeds cable system h…

There were several articles about a new "wardriving" technique that was talked about at Defcon (this topic and a bit more Defcon coverage here). In fact, this takes the driving out of the mix and inv…

There were demonstrations of some nasty javascript attacks at Black Hat as well (as if the wireless driver issues wasn't a big enough problem...) Javascript is a powerful language and can be used for…

"All you need to know about network security in one chart!!" I found an ad for this at javvin.com In addition to the "network security" charts.... they have other references.... "network communicatio…

Some people spend a lot of time finding ways to block the freeloaders from their wireless internet. Others find fun ways to mess with them.... They start off by settup up dhcpd.conf to carve out two …

Yesterday I had a bit of a realization. I had just been looking at a wireless router/firewall setup and was thinking about the firewalling rules (which seemed to be geared at the WIRELESS lan... i.e.…

Sans also brings this story about the Debian development server being compromised. Investigation is ongoing. The machine was gluck.debian.org and hosted CVS among other things (ddtp, lintian, people,…

Sans has a story on botnet traffic spotted coming from the TOR network. Now, I had to refresh my memory on what TOR is, but it's an anonymizing network, essentially a computer running TOR, would coll…

I saw this ZDNet post today with a tantalizing glimpse of Gdrive. It comes originally from cocaman.ch where he found a login page for something called Google Platypus, which is essentially a remotely…

and Internet Explorer use has dropped below 80% in the US. Currently 12.93% of online users browse with Firefox. Almost 40% of German web-browsers use Firefox to view the web. It's nice to see Firefo…

I really like printers with their own built in print server. They can be plugged into the network and some operating systems can just find them. Unfortunately most of the time Windows doesn't just fi…

The great firewall of China may be just an illusion in technical terms. This article describes the details of how things work.... Basically when "banned content" is detected, both ends of the connect…

For Windows system administrators that have sweated over the perils of usb drives and memory sticks.... Intelliadmin has a tool for you. It's a small utility that will allow to remotely disable usb d…

What follows are some notes taken on vmware server. Most are related to an install on ubuntu-server (NO GUI INSTALLED).... the main point of this is to have the host system take as FEW resources away…

I've heard rumors of how the 802.11 pre-n wireless networking hardware really KILLS nearby 802.11 wireless b/g networks. Today George Ou has some details. I really think this is a serious problem wit…

According to reuters data on US Nuclear Safety Administration employees (*some 1500) was stolen in a computer cracking incident. The NNSA is a semi-autonomous arm of the Energy Department and also gu…

So, I had the script all ready, I've got my x11vnc custom compiled to be as widely compatible as possible, I've tested thoroughly on the internal network. The next step was to test my x11vnc "one cut…

Well, I've got a nice way of doing "easy" one click (or one cut and paste) light desktop support for windows or linux, one uses ultravnc sc, the other uses x11vnc with a special wrapper script. So, w…

I've got to say, one of the things I really like about linux are the myriad of options for remotely administering a system. SSH is the one I use the most, but for the graphical you have x (especially…

As I said in the earlier posts, I was essentially looking for a "Single click" solution for linux VNC remote desktop support. A solution that doesn't require the remote support client to change firew…

So, the idea is that I wanted something "like" the Ultranvnc Single Click download, only for linux. The main idea being is that if someone is looking for a bit of desktop tech support on linux, we do…

Ok, some time back I'd done a writeup on UltraVNC SC, which is a nice customizable (windows version) VNC server that essentially let's someone doing remote support build their own downloadable .exe t…

In what feels like a continuation of recent bad news related to major hacks and data losses.....George Ou reports on a BIG hack of GoDaddy hosting customers. There was also a big hack-athon by Turkis…

I remember the first Windows XP vulnerability was a Upnp vulnerability. I have made one of my first visits on any new XP system a visit to grc.com to disable it on an XP workstation. But, it's the gr…

I thought this was a great idea.... rsync.net Okay for 2$ per GB of storage per month (or $24 per year for 1GB of storage) you can have your very own secure online storage drive. For you windows user…

Not long ago a customer offered me a slightly used Linksys BEFW11S4 ver. 4 wireless router for free. He had replaced it with an 802.11g router (this is only a b) shortly after purchase and said if I …

I think I've wrapped up the series on arp spoofing and it's implications for network security. I know there's nothing earth shattering here, most network security types are well aware of the problems…

So, let's say we want to have an open wireless access point for some reason. (Maybe offering it to guests if you're a business?) There are certainly a lot of BAD ways to give open wireless access. As…

So, if you haven't already had enough cause to tighten your wireless security.... we've been talking about arp poisoning (spoofing) and the basic conclusion is that IF an attacking machine is on the …

So, we've spent a couple articles talking about arp spoofing. It sounds really bad, it's a frighteningly easy way to do a "mitm" or man in the middle attack and anyone using arp spoofing could captur…

When a machine has been arp spoofed, ALL network traffic from it is likely passing through a "hostile" machine. So, NO, https and ssh traffic is not immune, it is travelling through a hostile machine…

So.... what is arp spoofing (poisoning).... and what are it's implications? ARP spoofing involves tricking a machine into thinking that you're machine is, yet another. Let's put this in IP address te…

So, for those that have a little bit of knowledge about network hardware, you've probably heard this. "You can't sniff switched networks".... wrong.... let's see what this is about. Older networking …

A while back I did a network security series and one of the points that I mentioned was that it's important to know what is normal for your network. In other words, what machines are NORMALLY connect…

I haven't had much time to look into this, but one of the mailservers I administer is typically configured to relay through mail.lig.bellsouth.net, with mail.averyjparker.com as a fallback. Sometime …

I ran into strange problems accessing a shared Novell Netware (5.0) folder. Everytime the folder was attempted to be accessed from multiple machines the window would freeze and if you waited long eno…

The last time I used openvpn, it was version 1.x and only supported a single connection per running process. So, if you had a server that you wanted to support multiple clients connecting, you had to…

I had hoped to do an article on metasploit in the not too distant future, but not as early as tonight.... However, I've made a couple of references to it in previous posts which, well, it would be ni…

So, according to D-Link there is a short list of access points that the DWL-800AP+ will repeat for. They are all d-link branded access points. It seems that there have been firmware updates to improv…

Ok, so here's the synopsis... I've spent the last few articles setting up a D-link DWL-800AP+ as a repeater for a linksys WAP11 (v. 1.1) As of the end of the last entry I had a bit of a problem with …

So, I set a WEP key on the linksys (WAP11 v. 1.1) and it promptly disappeared... it stopped responding (over the WIRED network) to my wap11gui admin tool. I quickly realized that part of the problem …

Ok, so now I had to add the new D-Link's MAC address to the list of authorized MAC's in the Linksys WAP11 (v. 1.1) For this, I call on wap11gui. Used to (since I use linux), I would have to suffer th…

So, now that I was "in" the DWL-800AP+ it was time to see if I could set it up as a repeater. I visited the "wireless" tab of the web based configuration and chose Repeater mode instead of AP mode an…

For starters, I hooked the D-link DWL-800AP+ up and connected it through a crossover cable to my usb network card. That way I could access it exclusively on one adapter and look online for informatio…

I've got a single access point for my wireless network layer at the house and unfortunately have at least one real "dead spot" in the house. As luck would have it that dead spot is at the couch... so…

At this point I've exhausted all the topics on network and computer security that I was eager to cover. As things change/ ideas strike I may well add to this series. One direction I see it going is t…

One thing I've already mentioned in this serious is using alternative programs like Mozilla Firefox instead of Internet Explorer, or Thunderbird, Eduora instead of Outlook Express. Even if you're not…

When you're not at your home network is probably one of those times you should be more on your guard. Wireless access points are very common and a greatly useful thing, but there are some steps you s…

After the Hamachi article I wanted to do a series on OpenVPN. I've used it before, but not since the 1.x days.... it's now at version 2.0.5 and has quite a bit more flexibility. When I first used it,…

Along the lines of "knowing your network" with the network security guide. Here are some of the most commonly used network ports. There are 65535 ports that can listen for a connection, so this is no…

So, most everything so far has been targetted to high speed internet users or business networks. That means if I use dialup I'm safe. Wrong. For starters, in many ways dialup internet is LESS of a ri…

A few days back I was at grc to run a "shields up" scan on a clients machine and found reference to their Security Now podcast (Leo Laporte and Steve Gibson.) The cast was about a VPN tool called Ham…

This may be one of the most important entries in this series. An important defence against those that would try to access your network is to constantly have the "security mindset". Ask yourself "do I…

The Hawking Technology Print Server (HPS1P) is a nice little parallel port to ethernet print server that can be configured to make a single printer available to multiple machines on a LAN (local area…

I remember I had a geography teacher once that was a former Marine and he said when he was growing up it was the height of the cold war and geography was interesting to him from a "know your enemy" p…

I remember many years ago watching a Dr. Who episode where a very important key was "hidden" in a display of many other keys. Kind of like hiding a tree in a forest. This concept is "security by obsc…

I'll confess to having a lot to learn about IP ethernet networking. I feel pretty comfortable with basic TCP/IP (v4), the concept of UDP vs. TCP ports, ICMP pings, etc... but ARP is something that I …

There are ways that risks can be avoided. Recently, there was what was called a zero-day exploit for Internet Explorer. As I write this, the exploit surfaced 3 weeks ago and tomorrow there will be a …

I REALLY like secure shell (SSH) for remote access to linux machines. You can do more than just a "telnet" like remote shell with it. (Port forwarding.) However, the default configuraton for the open…

Once upon a time I did an article about the biggest computer security vulnerability ever. I've also passed along the old "the most dangerous part of a car is the nut behind the wheel" joke. If you ha…

I've talked about Antivirus software as an essential. Today we're going to look at Antispyware software. There is a difference. By definition a virus is a piece of software that infects other files o…

Alright, so you're still reading this series and you're thinking. Look, I'm not protecting national security secrets. All I'm doing is (running a business|emailing my grandkids|using the web for rese…

In a small, trusted network you might be able to get away with weak passwords for file sharing for instance. What's a weak password? Anything you might find in a dictionary. Most people don't realize…

Once more into the breech... Ok you've taken account of the software and services on your pc. The next thing we need to talk about is knowing your network. Do you have any wireless access points? Not…

Deep breath time. We've covered a lot of good topics and it's important at this point to take a close look at what we've talked about and think. "Am I overwhelmed?" If so that's fine. Maybe you don't…