I was doing this  , but when it comes to the part where O should run these commands:  local-server#  ssh -NTCf -w 0:0 87.117.217.27 local-server#  ssh -NTCf -w 1:1 87.117.217.44   It says:  channel 0: open failed: administratively prohibited: open failed   How can I fix that?
When I open this ssh tunnel:  ssh -nXNT -p 22 localhost -L 0.0.0.0:8984:remote:8983   I get this error when trying to access the HTTP server running on localhost:8984:  channel 1: open failed: administratively prohibited: open failed   What does this error mean, and on which machine can you fix the problem?
So I paid for a minecraft account and everything but when I try to log in it says that I don't have a username. Is it an email or an email that you've made just for this account? How many combinations of groups are there where no member of a group has been with another member before? I found this hard to word in the title, so let me give an example. I have 16 students, and I want to split them up into 4 groups of 4. However, I want to make sure that every time I have a new combination of groups, that a student has never been with any of their new groupmates before. I found info on how to separate objects into groups, but not in only unique ways as I've described above. I think I figured this out the rote way, by assigning each student a number and then finding the unique combinations, and got 3. But I'd like to know the math behind it, and how it could be applied to other configurations (20 students w/ 4 groups of 5?). Thanks for any help you can give! How to best determine if a bike will fit without riding it In Harry Potter and the philosophers stone Harry was "receiving" his letters in a way that was so labour intensive. First, one was sent in the mail, and the others where then sent, either shoved into the letterbox or through the door cracks. It then it got, "out of hand," as twenty four letters found their way inside the house. The letter sender (Minerva, I do believe, Deputy Headmistress) must, obviously have known they were not getting to Harry, so why keep sending them? I cannot even believe Minerva sending more than thirty letters! Why not either,  A) Send the letters directly to Harry  OR  B) Show up at the house, to explain everything.  Why not do a more logical way of sending/explaining Harry's being? I can't retrieve my Facebook password I haven't been to my Facebook account in a while and I can't remember my password. When I try to have it reset, it goes to a security question, but I can't remember that either.    Is there anything I can do? What is / how can I get a student-safe power supply for electronics projects?  I'm looking for a student-safe power supply for solder less breadboard.  I'm developing a course to teach electrical engineering to grade school students as an after-school program.  I'm wrapping up the first course and I've learned a lot, including that I need to find a safer power supply.  We're mostly using 9V batteries and connecting them to the breadboard via alligator clips.  After lots of searching, I'm realizing that I need to turn towards the expert community for guidance.  I hope that with the rise of the Makers  this question will become increasingingly relevant with time as more kids get into electronics.  Inextricably linked to this question is what is the minimum power source to use.  I've liked using 9V batteries since we can connect to them using alligator clips; but I worry that they are just a little too powerful.  I can imagine them somehow starting a fire with them.  My #1 priority is to keep the students safe.  Kids just have no concept that they can cause damage to themselves and property.  When I ask "where is that smoke coming from?" I'll get a gleeful response from the student that is seeing how many batteries he could hook together and short out.   I really need to limit the damage they can do.  I mainly don't want anyone electrocuted or anything to catch fire.  Kids will routinely attach LEDs backwards, leave them like that and then act surprised when they explode.   After safety, I want to protect the equipment.  Kids will hook up a LED backwards all the time.  After protection, I want to give the kids feedback as to what is going on.  A light that indicates power is on would be awesome.  A light or siren or circuit break that indicated a short would be awesome too.  Battery powered supplies are slightly preferred, just to keep upfront costs low and to avoid having to run outlets to each table.  Boundaries:   We are only using simple LEDs, BJT transistors, resistors and maybe a timer IC.    Similiar Questions:       References:  Course details are here:   We currently sometimes use  from the Squishy Circuits Store and/or a 9V battery with alligator clips.  Epilogue  I found it tougher than expected to find a suitable wall wart, so I'm listing what I finally found for future reference.  I'm about to test the following combination:         Epilogue 2  A year-plus in, I've decided to drop the in-line power switch since it wasn't obvious when it was 'on' vs. 'off'.  I'm instead relying upon the students to unplug the rat-tail from the supply, which is quick and easy.  Also, since I'm primarily using this for a squishy-dough project, I'm experimenting with with using two button batteries instead of a wall power. SEO of  in  header Help Text not showing on I have a table inside of a pageblocksection and then inside of that I have an  that I am trying to utilize the default help text for but it's not showing up.  &lt;apex:pageBlockSection columns="1"&gt;   &lt;apex:outputPanel&gt;     &lt;table&gt; width="100%"&gt;       &lt;tr&gt;         &lt;td&gt;           &lt;apex:pageBlockSectionItem helpText="test text"&gt;             &lt;apex:inputCheckbox value="{!searchBySKU}" /&gt;             &lt;apex:outputLabel value="Search for this SKU or text in the SKU name" /&gt;           &lt;/apex:pageBlockSectionItem&gt;         &lt;/td&gt;       &lt;/tr&gt;     &lt;/table&gt;   &lt;/apex:outputPanel&gt; &lt;/apex:pageBlockSection&gt;   Any ideas why this doesn't work as I expect?  EDIT:  So, I just did some more testing and it creates the text if it's a direct child of the pageBlockSection. Is there any way to get around this restriction without going the fully custom route to do so? Trying to find the original story (I read it in Russian translation, original was most likely English unless it was Lem).  The story plot had artificial birds designed to serve as cops. The birds started attacking humans who were percieved as being aggressive towards anything alive. So they created more advanced birds to protect against the first ones. This worked for a while until the second kind started attacking humans as well. It ended with the idea that they would need another generation to attack the second-generation birds.  The story wasn't very long. I read it a while back (mid-1980s, which means the original was written even earlier, probably before 1980).  Despite a somewhat Asimov-like "misbehaving robots" topic, I'm pretty sure it wasn't Asimov. Purpose of hole in stove leading to oven I'm staying in a hotel and have access to a "electric coil stove" for one of the first times.  I accidentally turned on the oven light and saw that the light was shining up through only one of the stoves:    There's only a port from the oven into the top right stove, and note that the stove is not on.  Here's a view from within the oven:    Is there a hole here as a vent for the oven for some reason, or is this for the stove? I typically use a glass "flat-top stove" that doesn't have an oven underneath it. I've never seen a direct hole from a stove to the oven before, and have to wonder what the purpose is. Integral of Wiener Squared process I don't have a background of stochastic calculus.   It is known  that definite integral of standard  from $0$ to $t$ results in another Gaussian process with slice distribution that is normal distributed with mean equal to $0$ and variance $\frac{T^3}{3}$ i-e  $$ \int_0^{t} W_s ds \sim \mathcal{N}(0,\frac{t^3}{3})    $$  Question:  What if we square the standard Wiener process and then integrate i-e $$ \int_0^{t} W_s^2 ds \sim ?    $$  Would that be scaled Chi-square distributed ? calculating mean of a random variable raised to a power How do I align an image to centre? How do I align an image to centre?  In a beamer presentation I have a 2-3 items on a slide followed by an image. The image is not wide enough to cover whole slide, so it leaves around 30% space from right. How do I adjust it to leave enough space on both sides?  \begin{frame} \frametitle{Outlook} \begin{itemize} \item apps \item apps \item apps \includegraphics[scale=0.3]{P2P}     \end{itemize} \end{frame} I can't solve this problem:  Suppose $f$ is polynomial function of even degree $n$ with always $f\geq0$.  Prove that $f+f'+f''+\cdots+f^{(n)}\geq 0$. Let $\mathbf A, \mathbf B$ be Hermitian matrices of the same size. What is the characterization of $\mathbf A, \mathbf B$ such that $p(\lambda)=\det(\mathbf A-\lambda\mathbf B)=0$ has only real roots?   If $\mathbf B$ is positive definite (I corrected this), it is easy to see $p(\lambda)$ has only real roots. I have one website. I have two domain names that I want to point to the same site install.   So whether you go to name-one.com or name-two.com you see the exact same site.  Now, I can either set up name-two.com to serve 301 redirect header redirecting to name-one.com – or, I can set up name-two.com as a CNAME in the DNS pointing to name-one.com  What is the different implications for SEO on this? What is recommended?  I would guess it's better for branding to use a 301 redirect, so that visitors will see one consistent url for my site, right?  The reason I want the two domains is that I want a version with regional letters ('ö' instead of 'oe' ) in the name. How to show that all points are inside of unit circle? There are $n$ points on the plane. Any $3$ of them are inside of a unit circle. How to show that all points are inside of unit circle?  It is needed to prove that if there is a unit circle for each $3$  points which contains them, there is also a unit circle which contains all $n$ points. Undefined reference to static class member Why is logistic regression a linear classifier? Since we are using the logistic function to transform a linear combination of the input into a non-linear output, how can logistic regression be considered a linear classifier?  Linear regression is just like a neural network without the hidden layer, so why are neural networks considered non-linear classifiers and logistic regression is linear? What is the relationship between lands and mana in Magic and what do each of them do?  A good answer should especially include how a new player should think about them.    Note:  This is an attempt to create a canonical question about the relationship between lands and mana in Magic.  Beginners are often confused about this given the same symbols are used to mean different things across basic lands, non-basic lands, and mana costs.  This can lead to confusion about , about , or even about .