Things related to computer security in some way or another.
I admit that I’m not big on mobile phones (and I also admit this starts out on phones but it is a general thing and the rules apply to all types of nodes). I’ve pointed this out before, especially with regards to so-called smart technology. However, just because I personally don’t have much use for it, most of the time, does not mean that the devices should not be as secure as possible. Thus, I am firstly, giving credit to Apple (which all things considered is exceptionally rare) and Google (which is also very rare). I don’t like Apple particularly because of Steve Jobs’ arrogance (which I’ve also written about) but that is only part of it. At the same time, I do have fond memories of the early Apple computers. As for Google, I have serious issues with them but I haven’t actually put words to it here (or anywhere actually). But just because I don’t like them does not mean they can never do something right or that I approve of. To suggest that would be me being exactly as I call them out for. Well, since Apple and Google recently suggested they were to enable encryption by default for iOS and Android, I want to commend them for it: encryption is important.
There is the suggestion, most often by authorities (but not always as – and this is something I was planning on and I might still write about – Kaspersky showed not too long ago when they suggested similar things), that encryption (and more generally, privacy) is a problem and a risk to ones safety (and others’ safety). The problem here is that they are lying to themselves or they are simply ignorant (ignore the obvious please, I know it but it is besides the point for this discussion). They are also risking the people they claim to want to protect and they also risk themselves. Indeed, how many times has government data been stolen? More than I would like to believe and I don’t even try to keep track of it (statistics can be interesting but I don’t find the subject of government – or indeed other entity – failures all that interesting. Well, not usually). The problem really comes down to this, doesn’t it? If someone has access to your or another person’s private details, and it is not protected (or poorly protected), then what can be done to you or that other person if someone ELSE gets that information? Identify theft? Yes. Easier time gathering other information about you, who you work for, your friends, family, your friends’ families, etc.? Yes. One of the first things an attacker will do is gather information because it is that useful in attacks, isn’t it? And yet, that’s only two issues of many more, and both of those are serious.
On the subject of encryption and the suggestion that “if you have nothing to hide you have nothing to fear”, there is a simple way to obliterate it. All one needs to do is ask a certain (or similar) question and explanation following, directed at the very naive and foolish person (Facebook founder has suggested similar, as an example). The question is along the lines of: Is that why you keep your bank account, credit cards, keys, passwords, etc., away from others? You suggest that you shouldn’t have a need to keep something private because you have nothing to hide unless you did something wrong (and so the only time you need to fear is when you are in fact doing something wrong). But here you are hiding something (that you wouldn’t want others knowing, in other words, and with your logic it follows that you did something wrong), yet here you are hiding your private information. The truth is that if you have that mentality, you are either lying to yourself (and ironically hiding something from yourself and therefore not exactly following your suggestion) or you have hidden intent or reasons to want others information (which, ironically enough, is also hiding something – your intent). And at the same time, you know full well that YOU do want your information private (and YOU should want it private!).
But while I’m not surprised here, I still find it hard to fathom how certain people, corporations and other entities still think strong encryption is a bad thing. Never mind the fact that many high-profile cases of criminal data confiscated by police has been encrypted and yet revealed. Never mind the above. It is about control and power and we all know that the only people worthy of power are those who do not seek it but are somehow bestowed with it. So what am I getting at? It seems that, according to the BBC, the FBI boss is concerned about Apple’s and Google’s plans. Now I’m not going to be critical of this person, the FBI in general or anything of the sort. I made aware in the past that I won’t get in to the cesspool that is politics. However, what I will do is remark on something this person said but not remark on it by itself. Rather I will refer to something most amusing. What he said is this:
“What concerns me about this is companies marketing something expressly to allow people to place themselves beyond the law,” he said.
“I am a huge believer in the rule of law, but I am also a believer that no-one in this country is beyond the law,” he added.
But yet, if you look at the man page of expect, which allows interactive things that a Unix shell cannot do by itself, you’ll note the following capability:
- Cause your computer to dial you back, so that you can login without paying for the call.
That is, as far as I am aware, a type of toll fraud. Why am I even bringing this up, though? What does this have to do with the topic? Well, if you look further at the man page, you’ll see the following:
Thanks to John Ousterhout for Tcl, and Scott Paisley for inspiration. Thanks to Rob Savoye for Expect’s autoconfiguration code.
The HISTORY file documents much of the evolution of expect. It makes interesting reading and might give you further insight to this software. Thanks to the people mentioned in it who sent me bug fixes and gave other assis‐
Design and implementation of Expect was paid for in part by the U.S. government and is therefore in the public domain. However the author and NIST would like credit if this program and documentation or portions of them are
29 December 1994
I’m not at all suggesting that the FBI paid for this, and I’m not at all suggesting anyone in the government paid for it (it is, after all, from 1994). And I’m not suggesting they approve of this. But I AM pointing out the irony. This is what I meant earlier – it all comes down to WHO is saying WHAT and WHY they are saying it. And it isn’t always what it appears or is claimed. Make no mistake people, encryption IS Important, just like PCI compliance, auditing (regular corporation auditing of different types, auditing of medical professionals, auditing in everything), and anyone suggesting otherwise is ignoring some very critical truths. So consider that a reminder, if you will, of why encryption is a good thing. Like it or not, many humans have no problem with theft, no problem with manipulation, no problem with destroying animals or their habitat (Amazon forest, anyone?). It is by no means a good thing but it is still reality and not thinking about it is a grave mistake (including indeed literally, and yes, I admit that that is pointing out a pun). We cannot control others in everything but that doesn’t mean we aren’t responsible for our own actions and ignoring something that risks yourself (never mind others here) places the blame on you, not someone else.
Please observe the irony (that actually further proves my point, and that itself is ironic as well) that I suggest using the absolute path name and then I do not (with sed). This is what I mean by I am guilty of the same mistakes. It is something I have done over the years: work on getting in to the habit (of using absolute paths) and then it slides and then it happens all over again. This is why it is so important to get it right the first time (and this rule applies to security in general!). To make it worse, I knew it before I had root access to any machine (ever), years back. But this is also what I discussed with convenience getting in the way with security (and aliases only further add to the convenience/security conflict, especially with how certain aliases enable coloured output or some other feature). Be aware of what you are doing, always, and beware of not taking this all to heart. (And you can bet I’ve made a mental note to do this. Again.) Note that this rule won’t apply to shell built-ins unless you use the program too (some – e.g., echo – have both). The command ‘type’ is a built-in, though, and it is not a program. You can check by using the command itself like (type -P type will show nothing because there is no file on disk for type). Note also that I’ve not updated the commands where I show how aliases work (or commands that might be aliased). I’ve also not updated ls (and truthfully it probably is less of an issue, unless you are root, of course) but do note how to determine all ways a command can be invoked:
$ type -a ls ls is aliased to `ls --color=auto' ls is /usr/bin/ls
This could in theory could be only for Unix and its derivatives, but I feel there are similar risks in other environments. For instance, in DOS, extensions of programs had a priority so that if you didn’t type ‘DOOM2.EXE’ it would check – if I recall correctly, ‘DOOM2.BAT’ and ‘DOOM2.COM’ and then ‘DOOM2.EXE’. I don’t remember if that is the exact order but with no privilege separation you had the ability to rename files so that it if you wanted to write a wrapper to DOOM2 you could do it easily enough (I use DOOM2 in the example because not only was it one of my favourite graphical computer games, one I beat repeatedly I enjoyed it so much, much more than the original DOOM… I also happened to write a wrapper for DOOM2 itself, back then). Similarly, Windows doesn’t show extensions at all (by default, last I knew anyway) and so if a file is called ‘doom.txt.exe’ then double clicking on it would actually execute the executable instead of opening a text file (but the user would only see the name ‘doom.txt’). This is a serious flaw in multiple ways. Unix has its own issues with paths (but at least you can redefine them and there IS privilege separation). But it isn’t without its faults. Indeed, Unix wasn’t designed with security in mind and that is why so many changes have been implemented over the years (the same goes for the Internet main protocols – e.g., IP, TCP, UDP, ICMP – as well as other protocols at say, the application layer – all in their own ways). This is why things are so easy to exploit. This time I will discuss the issue of shell aliases.
General idea for finding the program (or script or…) to execute is also a priority. This is why when you are root (or using a privileged command) you should always use a fully-qualified name (primarily known as using the absolute file name). It is arguably better to always do this because, what if someone modified your PATH, added a file in your bin directory, updated your aliases, … ? Now you risk running what you don’t intend to. There is a way to determine all the ways it could be invoked but you should not rely on this, either. So the good, then the bad and then the ugly of the way this works (remember, security and convenience conflict with each other a lot, which is quite unfortunate but something that cannot be forgotten!). When I refer to aliases understand that aliases are even worse than the others (PATH and $HOME/bin/) in some ways, which I will get to at the ugly.
There is one case where aliases are fine (or at least not so bad as the others; the others is when you use options). It isn’t without flaws, however. Either way: let’s say you’re like me and you’re a member of the Cult of VI (as opposed to the Church of Emacs). You have vi installed but you also like vim features (and so have it installed too). You might want vi in some cases but vim in others (for instance, root uses vi and other users use vim, contrived example or not is up to your own interpretation). If you place in $HOME/.bashrc the following line, then you can override what happens when you type the command in question as follows:
$ /usr/bin/grep alias $HOME/.bashrc alias vi='vim'
Then typing ‘vi’ at the shell will open vim. Equally, if you type ‘vi -O file1 file2′ it will be run as ‘vim -O file1 file2′. This is useful but even then it has its risks. It is up to the user to decide, however (and after all, if a user is compromised you should assume the system is compromised because if it hasn’t been already it likely will be, so what’s the harm? Well I would disagree that there is no harm – indeed there is – but…)
THE BAD AND THE UGLY
Indeed, this is both bad and ugly. First, the bad part: confusion. Some utilities have conflicting options. So if you alias a command to use your favourite options, what if one day you want to use another option (or see if you like it) and you are used to typing the basename (so not the absolute name)? You get an error about conflicting options (or you get results you don’t expect)? Is it a bug in the program itself? Well, check aliases as well as where else the problem might occur. In bash (for example) you can use:
$ type -P diff /usr/bin/diff
However, is that necessarily what is executed? Let’s take a further look:
$ type -a diff diff is aliased to `diff -N -p -u' diff is /usr/bin/diff
So no, it isn’t necessarily the case. What happens if I use -y, which is a conflicting output type? Let’s see:
$ diff -y diff: conflicting output style options diff: Try 'diff --help' for more information.
Note that I didn’t even finish the command line! It detected invalid output styles and that was it. Yet it appears I did not actually specify conflicting output style types – clearly I only specified one option so this means indeed the alias was used, which means that while I specified options, those options are included and not excluding other options (certain programs will take the last option as the one that rules but not all do and diff does not here). If however, I were to do:
$ /usr/bin/diff -y /usr/bin/diff: missing operand after '-y' /usr/bin/diff: Try '/usr/bin/diff --help' for more information.
There we go: the error as expected. That’s how you get around it. But let’s move on to the ugly because “getting around it” is only if you remember and more so do not ever rely on aliases! Especially do not rely on it for certain commands. This cannot be overstated! The ugly is this:
It is unfortunate but Red Hat Linux based distributions have this by default and not only is it baby-sitting (which is both risky but also obnoxious much of the time … something about the two being related) it has an inherent risk. Let’s take a look at default alias for root’s ‘rm':
# type -a rm rm is aliased to `rm -i' rm is /usr/bin/rm
-i means interactive. rm is of course remove. Okay so what is the big deal, surely this is helpful because as root you can wipe out the entire file system? Okay that’s fine but you can also argue the same with chown and chmod (always be careful recursively with these – well in general even – utilities… but these specifically are dangerous; they can break the system with ease). I’ll get to those in a bit. The risk is quite simple. You rely on the alias which means you never think about the risks involved; indeed, you just type ‘n’ if you don’t want to delete the files encountered (and you can send yes to all by piping ‘yes’, among other ways, if you wanted to at a one time avoid the nuisance). The risk then is, what if by chance you are an administrator (a new administrator) on another (different) system and it does not have the -i option? You then go to do something like (and one hopes you aren’t root but I’m going to show it as if I was root – in fact I’m not running this command – because it is serious):
# /usr/bin/pwd /etc # rm * #
The pwd command was more of to show you a possibility. Sure, there are directories there that won’t be wiped out because there was no recursive option (and no force which is necessary for directories that are not empty), but even if you are fast with sending an interrupt (usually ctrl-c but can be shown and also set with the stty command, see stty –help for more info), you are going to have lost files. The above would actually have shown that some files were directories after the rm * but before the last #, but all the files in /etc itself would be gone. And this is indeed an example of “the problem is that which is between the keyboard and chair” or “PEBKAC” (“problem exists between keyboard and chair”) or even “PICNIC” (problem in chair not in computer”), among others. Why is that? Because you relied on something one way and therefore never thought to get in the habit of being careful (and either always specifying -i or using the command in a safe manner like always making sure you know exactly what you are typing). As for chown and chmod? Well if you look at the man pages, you see the following options (for both):
--no-preserve-root do not treat '/' specially (the default) --preserve-root fail to operate recursively on '/'
Now if you look at the man page for rm, and see these options, you’ll note a different default:
--no-preserve-root do not treat '/' specially --preserve-root do not remove '/' (default)
The problem? You might get used to the supposed helpful behaviour with rm which would show you:
rm: it is dangerous to operate recursively on ‘/’ rm: use --no-preserve-root to override this failsafe
So you are protected from your carelessness (you shouldn’t be careless… yes it happens and I’m guilty of it too, but this is one of the things backups were invented for, as well as only being as privileged as is necessary and only for the task in hand). But that protection is a mistake itself. This is especially true when you then look at chown and chmod, both of which are ALSO dangerous when recursively done on / (actually on many directories recursively, example to not do it on is /etc as that will break a lot of things, too). And don’t even get me started on the mistake of: chown -R luser.luser .*/ because even if you are in /home/luser/lusers, then as long as you are root (it is a risk for users to change owners and so therefore only root can do that) then you will be changing the root file system and everything under it (/etc, /bin/, /dev/, everything) to be owned by luser as the user and luser as the group. Hope you had backups. You’ll definitely need them. Oh, and yes, any recursive action on .* is a risky thing indeed. To see this in action in a safe manner, as some user, in their home directory or even a sub-directory of their home directory, try the following:
$ /usr/bin/ls -alR .*
… and you’ll notice it going to /home and then / and everything below it! The reason is the way path globbing works (try man -s 7 glob). I’d suggest you read the whole thing but the one in particular is under Pathnames.
So yes, if you rely on aliases which is relying on not thinking (which is a problem itself in so many ways) then you’re setting yourself up for a disaster. Whether that disaster in fact happens is not guaranteed but one should be prepared and not set themselves up for it in the first place. And unfortunately some distributions set you up for this by default. I’m somewhat of the mind to alias rm to ‘rm –no-preserve-root’ but I think most would consider me crazy (they’re probably more correct than they think). As for the alias rm in /root/.bashrc, here’s how you remove it (or maybe if you prefer to comment it out). Just like everything else, there’s many ways, this is at the command prompt:
# /usr/bin/sed -i 's,alias \(rm\|cp\|mv\),#alias \1,g' /root/.bashrc
Oh, by the way, yes, cp and mv (hence the command above commenting all three out) are also aliased in root’s .bashrc to use interactive mode and yes the risks are the same (you risk overwriting files when you aren’t on an aliased account and this might even be the same system that you are used to it with root but you don’t have it on all your accounts which means if you were just as root and remembered it was fine then you logout back to your normal, non-privileged user and you do some maintenance there, what happens if you then use one of those commands that is not aliased to -i? Indeed, aliases can be slightly good, bad and very ugly). Note that (although you should do this anyway) even if you were to source (by ‘source /root/.bashrc’ or equally ‘. /root/.bashrc’) the file again the aliases would still exist because it didn’t unalias them (you could of course run that too but better is log out and the next time you are logged in you won’t have that curse upon you).
One more thing that I think others should be aware of as it further proves my point about forgetting aliases (whether you have them or not). The reason I wrote this is twofold:
- First, I’ve delayed the alias issue with rm (and similar commands) but it is something I’ve long thought of and it is indeed a serious trap.
- Second, and this is where I really make the point: the reason this came up is one of my accounts on my server had the alias for diff as above. I don’t even remember setting it up! In fact, I don’t even know what I might have used diff for, with that account! That right there proves my point entirely (and yes, I removed it). Be aware of aliases and always be careful especially as a privileged user…
One of the things I often write about is how open source is in fact good for security. Some will argue the opposite to the end. But what they are relying on, at best, is security through obscurity. Just because the source code is not readily available does not mean it is not possible to find flaws or even reverse engineer it. It doesn’t mean it cannot be modified, either. I can find – as could anyone else – countless examples of this. I have personally added a feature to a Windows dll file – a rather important one, that is shell32.dll – in the past. I then went on to convince Windows file integrity check to not only see the modified file as correct but if I were to have replaced it with the original, unmodified one, then it would have replaced it with my modified version. And how did I add a feature without the source code? My point exactly. So to believe you cannot uncover how it works (or, as some will have you believe, modify and/or add features) is a huge mistake. But whatever. This is about open source and security. Before I can get in to that, however, I want to bring up something else I often write about at times.
That thing I write about is this: one should always admit to mistakes. You shouldn’t get angry and you shouldn’t take it as anything but a learning opportunity. Indeed, if you use it to better yourself, better whatever you made the mistake in (let’s say you are working on a project at work and you make a mistake that throws the project off in some way) and therefore better everything and everyone involved (or around), then you have gained and not lost. Sure, you might in some cases actually lose something (time and/or money, for example) but all good comes with bad and the reverse is true too: all bad comes with good. Put another way, I am by no means suggesting open source is perfect.
The only thing that is perfect is imperfection.
I thought of that the other day. Or maybe better put, I actually got around to putting it in my fortune file (I keep a file of pending ideas for quotes as well as the fortune file itself). The idea is incredibly simple: the only thing that will consistently happen without failure is ‘failure’, time and time again. In other words, there is no perfection. ‘Failure’ because it isn’t a failure if you learn from it; it is instead successfully learning yet another thing and is another opportunity to grow. On the subject of failure or not, I want to add a more recent quote (this was thought of earlier this month or later in August than when I originally posted this, which was 15 August) that I think really nails this idea very well:
There is no such thing as human weakness, there is only
strength and… those blinded by… the fallacy of perfection.
In short, the only weakness is the product of ones’ mind. There is no perfection but if you accept this you will be much further ahead (if you don’t accept it you will be less able to take advantage of what imperfection offers). All of this together is important, though. I refer to admitting mistakes and how it is only a good thing. I also suggest that open source is by no means perfect and therefore to be critical of it, as if it is less secure, is flawed. But here’s the thing. I can think of a rather critical open source library that is used by a lot of servers, that has had a terrible year. One might think with this, and specifically what it is (which I will get to in a moment), it is somehow less secure or more problematic. What is this software? Well, let me start by noting the following CVE fixes that were pushed in to update repositories, yesterday:
– fix CVE-2014-3505 – doublefree in DTLS packet processing
– fix CVE-2014-3506 – avoid memory exhaustion in DTLS
– fix CVE-2014-3507 – avoid memory leak in DTLS
– fix CVE-2014-3508 – fix OID handling to avoid information leak
– fix CVE-2014-3509 – fix race condition when parsing server hello
– fix CVE-2014-3510 – fix DoS in anonymous (EC)DH handling in DTLS
– fix CVE-2014-3511 – disallow protocol downgrade via fragmentation
To those who are not aware, I refer to the same software that had Heartbleed vulnerability. It therefore is also the same software as some other CVE fixes not too long after that. And indeed it seems that OpenSSL is having a bad year. Well, whatever – or perhaps better put, whomever – is the source (and yes, I truly do love puns) of the flaws, is irrelevant. What is relevant is this: they clearly are having issues. Someone or some people adding the changes are clearly not doing proper sanity checks and in general not auditing well enough. This just happens, however. It is part of life. It is a bad patch (to those that do not like puns, I am sorry, but yes, there goes another one) of time for them. They’ll get over it. Everyone does, even though it is inevitable that it happens again. As I put it: This just happens.
To those who want to be critical, and not constructively critical, I would like to remind you of the following points:
- Many websites use OpenSSL to encrypt your data and this includes your online purchases and other credit card transactions. Maybe instead of being only negative you should think about your own mistakes more rather than attacking others? I’m not suggesting that you not considering yours, but in the case you are not, think about this. If nothing else, consider that this type of criticism will lead to nothing and since OpenSSL is critical (I am not consciously and deliberately making all these puns, it is just in my nature) then this can lead to no good and certainly is of no help.
- No one is perfect, as I not only suggested above, but also suggested at other times. I’ll also bring it up again, in the future. Because thinking yourself infallible is going to lead to more embarrassment than if you understand this and prepare yourself, always being on the look out for mistakes and reacting appropriately.
- Most importantly: this has nothing to do with open source versus closed source. Closed source has its issues too, including less people that can audit it. The Linux kernel, for example, and I mean the source code thereof, is on many people’s computers and that is a lot to see any issues. Issues still have and still will happen, however.
With that, I would like to end with one more thought. Apache, the organization that maintains the popular web server as well as other projects, is really to be commended for their post-attack analyses. They have a section on their website, which details attacks and the details include what mistakes they made, what happened, what they did to fix it as well as what they learned. That is impressive. I don’t know if any closed source corporations do that, but either way, it is something to really think about. It is genuine, it takes real courage to do it, and it benefits everyone. This is one example. There are immature comments there but that shows just how impressive Apache is to do this (they have other incident reports I seem to recall). The specific incident is reported here.
Just to clarify a few points. Firstly, I have five usable IP addresses. That is because, like I explain below, some of the IPs are not usable for systems but instead have other functions. Secondly, the ports detected as closed and my firewall returning icmp errors. It is true I do return that but of course there’s missing ports there and none of the others are open (that is, none have services bound to them), either. There are times I flat out drop packets to the floor but if I have the logs I’m not sure which log file it is (due to log rotation), to check for sure. There’s indeed some inconsistencies. But the point remains the same: there was absolutely nothing running on any of those ports just like the ports it detected as ‘stealth’ (which is more like not receiving a response and what some might call filtered but in the end it does not mean nothing is there and it does not mean you are some how immune to attacks). Third, I revised the footnote about FQDN, IP addresses and what they resolve to. There’s a few things that I was not clear with and in some ways unfair with, too. I was taking an issue to one thing in particular and I did a very poor job of it I might add (something I am highly successful at I admit).
One might think I have better things to worry about than write about a known charlatan but I have always been somewhat bemused with his idea of security (perhaps because he is clueless and his suggestions are unhelpful to those who believe him which is a risk to everyone). More importantly though, I want to dispel the mythical value of what he likes to call stealth ports (and even more than that anything that is not stealth is somehow a risk). This, however, will not only tackle that, it will be done in what some might consider an immature way. I am admitting it full on though. I’m bored and I wanted to show just how useless his scans are by making a mockery of those scans. So while this may seem childish to some, I am merely having fun while writing about ONE of MANY flaws Steve Gibson is LITTERED with (I use the word littered figuratively and literally).
So let’s begin, shall we? I’ll go in the order of pages you go through to have his ShieldsUP! scan begin. First page I get I see the following:
Without your knowledge or explicit permission, the Windows networking technology which connects your computer to the Internet may be offering some or all of your computer’s data to the entire world at this very moment!
Greetings indeed. Firstly, I am very well aware of what my system reveals. I also know that this has nothing to do with permission (anyone who thinks they have a say in what their machine reveals, when connecting to the Internet – or phone to a phone network, or … – is very naive and anyone suggesting that there IS permission involved, is a complete fool). On the other hand, I was not aware I am running Windows. You cannot detect that yet you scan ports which would give you one way to determine OS? Here’s a funny part of that: since I run a passive fingerprinting service (p0f) MY SYSTEM determined your server’s OS (well, technically, kernel but all things considering, that is the most important bit, isn’t it? Indeed it is not 100% correct, however, but that goes with fingerprinting in general and I know that it DOES detect MY system correctly). So not only is MY host revealing information YOURS is too. Ironic? Absolutely not! Amusing? Yes. And lastly, let’s finish this part up: “all of your computer’s data to the entire world at this very moment!” You know, if it were not for the fact people believe you, that would be hilarious too. Let’s break that into two parts. First, ALL of my computer’s data? Really now? Anyone who can think rationally knows that this is nothing but sensationalism at best but much more than that: it is you proclaiming to be an expert and then ABUSING that claim to MANIPULATE others into believing you (put another way: it is by no means revealing ALL data, not in the logical – data – sense or physical – hardware – sense). And the entire world? So you’re telling me that every single host on the Internet is analyzing my host at this very moment? If that were the case, my system’s resources would be too full to even connect to your website. Okay, context would suggest that you mean COULD but frankly I already covered that this is not the case (I challenge you to name the directory that is most often my current working directory let alone know that said directory even exists on my system).
If you are using a personal firewall product which LOGS contacts by other systems, you should expect to see entries from this site’s probing IP addresses: 184.108.40.206 -thru- 220.127.116.11. Since we own this IP range, these packets will …
Well, technically, based on that range, your block is 18.104.22.168/28. And technically your block includes (a) the network address, (b) the default gateway and (c) the broadcast address. That means that the IPs that would be probing is in the range more like ‘22.214.171.124’ – ‘126.96.36.199’. And people really trust you? You don’t even know basic networking and they trust you with security?
Your Internet connection’s IP address is uniquely associated with the following “machine name”:
Technically that is the FQDN (fully-qualified domain name), not “machine name” as you put it. You continue in this paragraph:
The string of text above is known as your Internet connection’s “reverse DNS.” The end of the string is probably a domain name related to your ISP. This will be common to all customers of this ISP. But the beginning of the string uniquely identifies your Internet connection. The question is: Is the beginning of the string an “account ID” that is uniquely and permanently tied to you, or is it merely related to your current public IP address and thus subject to change?
Again, your terminology is rather mixed up. While it is true that it you did a reverse lookup on my IP, it isn’t exactly “reverse DNS”. But since you are trying to simplify (read: dumb it down to your level) it for others, and since I know I can be seriously pedantic, I’ll let it slide. But it has nothing to do with my Internet connection itself (I have exactly one). It has to do with my IP address of which I have many (many if you consider my IPv6 block, but only 5 if you consider IPv4). You don’t exactly have the same FQDN on more than one machine any more than you have the same IP on more than one network interface (even on the same system). So no, it is NOT my Internet connection but THE specific host that went to your website and in particular the IP assigned to that host I connected from. And the “string” has nothing to do with an “account ID” either. But I’ll get back to that in a minute.
The concern is that any web site can easily retrieve this unique “machine name” (just as we have) whenever you visit. It may be used to uniquely identify you on the Internet. In that way it’s like a “supercookie” over which you have no control. You can not disable, delete, or change it. Due to the rapid erosion of online privacy, and the diminishing respect for the sanctity of the user, we wanted to make you aware of this possibility. Note also that reverse DNS may disclose your geographic location.
I can actually request a different block from my ISP and I can also change the IP on my network card. Then the only thing that is there is my IP and its FQDN (that is not in use and I can change the FQDN as I have reverse delegation yet according to you I cannot do any of that). I love your ridiculous terminology though. Supercookie? Whatever. As for it giving away my geographic location, let me make something very clear: the FQDN is irrelevant without the IP address. While it is true that the name will (sometimes) refer to a city it isn’t necessarily the same city or even county as the person USING it. The IP address is related to the network; the hostname is a CONVENIENCE for humans. You know, it used to be that host -> IP was done without DNS (since it didn’t exist) but rather a file that maintains the mapping (and still is used albeit very little). The reason it exists is for convenience and in general because no one would be able to know the IP of every domain name. Lastly, not all IPs resolve into a name.
If the machine name shown above is only a version of the IP address, then there is less cause for concern because the name will change as, when, and if your Internet IP changes. But if the machine name is a fixed account ID assigned by your ISP, as is often the case, then it will follow you and not change when your IP address does change. It can be used to persistently identify you as long as you use this ISP.
The occasions it resembles the IP is when the ISP has authority of the in-addr.arpa DNS zone of (your) IP and therefore has their own ‘default’ PTR record (but they don’t always have a PTR record which your suggestion does not account for; indeed, I could have removed the PTR record for my IP and then you’d have seen no hostname). But this does not indicate that it is static or not. Indeed, even dynamic IPs typically (not always) have a PTR record. Again, the name does not necessarily imply static: it is the IP that matters. And welcome to yesteryear… in these days you typically pay extra for static IPs but you suggest it is quite often that your “machine name is a fixed account ID” (which itself is completely misuse of terminology). On the other hand, you’re right: it won’t change when your IP address changes because the IP is relevant, not the hostname! And if your IP changes then it isn’t so persistent in identifying you, is it? It might identify your location but as multiple IPs (dynamic) and not a single IP.
There is no standard governing the format of these machine names, so this is not something we can automatically determine for you. If several of the numbers from your current IP address (188.8.131.52) appear in the machine name, then it is likely that the name is only related to the IP address and not to you.
Except ISP authentication logs and timestamps… And I repeat the above: the name can include exactly as you suggest and still be static!
But you may wish to make a note of the machine name shown above and check back from time to time to see whether the name follows any changes to your IP address, or whether it, instead, follows you.
Thanks for the suggestion but I think I’m fine since I’m the one that named it.
Now, let’s get to the last bit of the ShieldsUP! nonsense.
Results from scan of ports: 0-10550 Ports Open
72 Ports Closed
984 Ports Stealth
1056 Ports TestedNO PORTS were found to be OPEN.Ports found to be CLOSED were: 0, 1, 2, 3, 4, 5, 6, 36, 37,
64, 66, 96, 97, 128, 159, 160,
189, 190, 219, 220, 249, 250,
279, 280, 306, 311, 340, 341,
369, 371, 399, 400, 429, 430,
460, 461, 490, 491, 520, 521,
550, 551, 581, 582, 608, 612,
641, 642, 672, 673, 734, 735,
765, 766, 795, 796, 825, 826,
855, 856, 884, 885, 915, 916,
945, 946, 975, 976, 1005, 1006,
1035, 1036Other than what is listed above, all ports are STEALTH.
TruStealth: FAILED – NOT all tested ports were STEALTH,
– NO unsolicited packets were received,
– A PING REPLY (ICMP Echo) WAS RECEIVED.
The ports you detected as “CLOSED” and not “STEALTH” were in fact returning an ICMP host-unreachable. You fail to take into account the golden rule of firewalls: that which is not explicitly permitted is forbidden. That means that even though I have no service running on any of those ports I still reject the packets to it. Incidentally, some ports you declared as “STEALTH” did exactly the same (because I only allow the ports in a specific IP block as the source network). The only time I drop packets to the floor is when state checks fail (e.g., a TCP SYN flag is set but it is already a known connection). I could prove that too, because I actually went and had you do the scan a second time but this time I added specific iptables rules for your IP block which changed the results quite a bit and indeed I used the same ICMP error code.
As for ping: administrators that block ping outright need to be hit over the head with a pot of sense. Rate limit by all means, that is more than understandable, but blocking ICMP echo requests (and indeed replies) only makes troubleshooting network connectivity issues more of a hassle and at the same time does absolutely nothing for security (fragmented packets and anything that can be abused obviously are dealt with differently because they are different!). Indeed, if they are going to attack they don’t really care if you respond to ICMP requests. If there is a vulnerability they will go after that and frankly hiding behind your “stealth” ports is only a false sense of security and/or security through obscurity (which is a false sense of security and even more harmful at the same time). Here’s two examples: First, if someone sends you a link (example: in email) and it seems to you to be legit and you click on it (there’s a lot of this in recent years and is ever increasing), the fact you have no services running does not mean you somehow are immune to XSS, phishing attacks, malware, or anything else. Security is, always has been and always will be a many layered thing. Secondly: social engineering.
And with that, I want to finish with the following:
If anyone wants the REAL story about Steve Gibson, you need only Google for “steve gibson charlatan” and see the many results. I can vouch for some of them but there really is no need for it – the evidence is so overwhelming that it doesn’t need any more validation. Here’s a good one though (which also shows his ignorance as well as how credible his proclamations are): http://www.theregister.co.uk/2002/02/25/steve_gibson_invents_broken_syncookies/ (actually it is a really good one). If you want a list of items, check the search result that refers to Attrition.org and you will see just how credible he is NOT. A good example is the one that links to a page about Gibson and XSS flaws which itself links to: http://seclists.org/vuln-dev/2002/May/25 which is itself offers a great amount of amusement (note that some of the links are no longer valid as it was years ago but that is the one at seclists.org and not the only incident).
 Technically, what his host is doing is taking the IP address and resolving it to a name (which is querying the PTR record as I refer to above). Since I have reverse delegation (so have authority) and have my own domain (which I also have authority of) I have my IPs resolve to fully-qualified domain names as such. FQDN is perhaps not the best wording (nor fair, especially) on my part in that I was abusing the fact that he is expecting normal PTR records that an ISP has rather than a server with proper an A record with a matching PTR record. What he refers to is as above: resolving the IP address to a name, which does not have to have a name. Equally, even if a domain exists by name, it does not have to resolve to an IP (“it is only registered”). He just gave it his own name for his own ego (or whatever else).
I’ve thought of this in the past and I’ve been trying to do more things (than usual) to keep me busy (there’s too few things that I spend time doing, more often than not), and so I thought I would finally get to this. So, when it comes to SELinux, there are two schools of thought:
- Enable and learn it.
- Disable it; it isn’t worth the trouble.
There is also a combination of the two: put it in permissive mode so you can at least see alerts (much like logs might be used). But for the purpose of this post, I’m going to only include the mainstream thoughts (so 1 and 2, above). Before that though, I want to point something out. It is indeed true I put this in the security category but there is a bit more to it than that, as those who read it will find out at the end (anyone who knows me – and yes this is a hint – will know I am referring to irony, as the title refers to). I am not going to give a suggestion on the debate of SELinux (and that is what it is – a debate). I don’t enjoy and there is no use in having endless debates on what is good, bad, what should be done, debating on whether or not to do something or even debating on a debating (and yes the latter two DO happen – I’ve been involved in a project that had this and I stayed out of it and did what I knew to be best for the project over all). That is all a waste of time and I’ll leave it to those who enjoy that kind of thing. Because indeed the two schools of thought do involve quite a bit of emotion (something I try to avoid itself, even) – they are so passionate about it, so involved in it, that it really doesn’t matter what is suggested from the other side. It is taking “we all see and hear what we want to see and hear” to the extreme. This is all the more likely when you have two sides. It doesn’t matter what they are debating and it doesn’t matter how knowledgeable they are or are not and nothing else matters either: they believe their side’s purpose so strongly, so passionately that much of it is mindless and futile (neither side sees anything but their own side’s view). Now then…
Let’s start with the first. Yes, security is indeed – as I’ve written about before – layered and multiple layers it always has been and always should be. And indeed there are things SELinux can protect against. On the other hand, security has to have a balance or else there is even less security (password aging + many different accounts so different passwords + password requirements/restrictions = a recipe for disaster). In fact, it is a false sense of security and that is a very bad thing. So let’s get to point two. Yes, that’s all I’m going to write on the first point. As I already wrote, there isn’t much to it notwithstanding endless debates: it has pros and it has cons, that’s all there is to it.
Then there’s the school of thought that SELinux is not worth the time and so should just be disabled. I know what they mean, not only with the labelling of the file systems (I wrote about this before and how SELinux itself has issues at times all because of labels, and so you have to have it fix itself). That labelling issue is bad itself but then consider how it affects maintenance (even worse for administrators that maintain many systems). For instance, new directories in Apache configuration, as one example. Yes, part of this is laziness but again there’s a balance. While this machine (the one I write from, not xexyl.net) does not use it I still practice safe computing, I only deal with software in main repositories, and in general I follow exactly as I preach: multiple layers of security. And finally, to end this post, we get to some irony. I know those who know me well enough will also know very well that I absolutely love irony, sarcasm, satire, puns and in general wit. So here it is – and as a warning – this is very potent irony so for those who don’t know what I’m about to write, prepare yourselves:
You know all that talk about the NSA and its spying (nothing alarming, mind you, nor anything new… they’ve been this way a long long time and which country doesn’t have a spy network anyway? Be honest!), it supposedly placing backdoors in software and even deliberately weakening portions of encryption schemes? Yeah, that agency that there’s been fuss about ever since Snowden started releasing the information last year. Guess who is involved with SELinux? Exactly folks: the NSA is very much part of SELinux. In fact, the credit to SELinux belongs to the NSA. I’m not at all suggesting they tampered with any of it, mind you. I don’t know and as I already pointed out I don’t care to debate or throw around conspiracy theories. It is all a waste of time and I’m not about to libel the NSA (or anyone, any company or anything) about anything (not only is it illegal it is pathetic and simply unethical, none of which is appealing to me), directly or indirectly. All I’m doing is pointing out the irony to those that forget (or never knew of) SELinux in its infancy and linking it with the heated discussion about the NSA of today. So which is it? Should you use SELinux or not? That’s for each administrator to decide but I think actually the real thing I don’t understand (but do ponder about) is: where do people come up with the energy, motivation and time to bicker about the most unimportant, futile things? And more than that, why do they bother? I guess we’re all guilty to some extent but some take it too far too often.
As a quick clarification, primarily for those who might misunderstand what I find ironic in the situation, the irony isn’t that the NSA is part of (or was if not still) SELinux. It isn’t anything like that. What IS ironic is that many are beyond surprised (and I still don’t know why they are but then again I know of NSA’s history) at the revelations (about the NSA) and/or fearful of their actions and I would assume that some of those people are those who encourage use of SELinux. Whether that is the case and whether it did or did not change their views, I obviously cannot know. So put simply, the irony is that many have faith in SELinux which the NSA was (or is) an essential part of and now there is much furor about the NSA after the revelations (“revelations” is how I would put it, at least for a decent amount of it).