Proxy SSH to hide endpoints Has anyone done SSH proxying that is transparent to the user, but the end host they are routed to is determined by any of the following:  username, identity key, DNS hostname.  I guess DNS hostname isn't possible with the protocol, but it could use the identity key.  For example, I want users to be able to all SSH to the same machine, but they end up on different VPS nodes:  ssh -i identity_rsa user@example.com.    There are a few very nice features of doing this:   The RSA host key is the same no matter what VPS you SSH into.   The hostname could be the same, or (dubious) it could route on subdomain names.  I'm not sure if this is in the protocol or it only uses the IP address to connect to a TCP socket. Zero configuration on the client side (proxy commands, multiple ssh tunnels, etc) All traffic is funneled through a gateway.   I'm worried this requires a custom (legitimate) MitM SSH server, because I want a normal end-to-end SSH connection that can do SCP and agent-forwarding.    Can agent forwarding work with forced commands?  Could I create forced commands based on the public key, call SSH -A to the inside host?
Is there a name based virtual host SSH reverse proxy? I've grown quite fond of HTTP reverse proxies in our development environment and found the DNS based virtual host reverse proxy quite useful. Having only one port (and the standard one) open on the firewall makes it much easier for management.  I'd like to find something similar to do SSH connections but haven't had much luck. I'd prefer not to simply use SSH tunneling since that requires opening port ranges other than the standard. Is there anything out there that can do this?  Could HAProxy do this?
Styling each feature of a layer individually I’ve a PostGIS table which is published as a Geoserver layer. Every feature in the table has some attributes that should style that feature (e.g color, size, opacity, external graphic url, ... etc).  I can create an SLD document and let it read its styling attributes from the table using &lt;PropertyName&gt;, but the problem is more complex than this, for example: some points features need to be styled as a simple circles, while some other need to be styled as external-graphic images. And from the SLD Reference, the SLD PointSymbolizer must have either &lt;Mark&gt; or &lt;ExternalGraphic&gt; element, for that reason I should create two rules one for the simple point symbolizer and the other for the external-graphic point symbolizer, and should add a filter to each rule so that it deals only with the appropriate features, something like:  &lt;FeatureTypeStyle&gt;     &lt;Rule&gt;         &lt;ogc:Filter&gt;             &lt;ogc:PropertyIsEqual&gt;                 &lt;ogc:PropertyName&gt;is-external-graphic&lt;/ogc:PropertyName&gt;                 &lt;ogc:Literal&gt;0&lt;/ogc:Literal&gt;             &lt;/ogc:PropertyIsEqual&gt;         &lt;/ogc:Filter&gt;         &lt;PointSymbolizer&gt;             &lt;Graphic&gt;                 &lt;Mark&gt;                     &lt;WellKnownName&gt;circle&lt;/WellKnownName&gt;                     &lt;Fill&gt;                         &lt;CssParameter name="fill"&gt;                             &lt;ogc:PropertyName&gt;fill-color&lt;/ogc:PropertyName&gt;                         &lt;/CssParameter&gt;                     &lt;/Fill&gt;                 &lt;/Mark&gt;                 &lt;Size&gt;6&lt;/Size&gt;             &lt;/Graphic&gt;         &lt;/PointSymbolizer&gt;     &lt;/Rule&gt;     &lt;Rule&gt;         &lt;ogc:Filter&gt;             &lt;ogc:PropertyIsEqual&gt;                 &lt;ogc:PropertyName&gt;is-external-graphic&lt;/ogc:PropertyName&gt;                 &lt;ogc:Literal&gt;1&lt;/ogc:Literal&gt;             &lt;/ogc:PropertyIsEqual&gt;         &lt;/ogc:Filter&gt;         &lt;PointSymbolizer&gt;             &lt;Graphic&gt;                 &lt;ExternalGraphic&gt;                     &lt;OnlineResource                xlink:type="simple"                xlink:href="smileyface.png" /&gt;                     &lt;Format&gt;image/png&lt;/Format&gt;                 &lt;/ExternalGraphic&gt;                 &lt;Size&gt;6&lt;/Size&gt;             &lt;/Graphic&gt;         &lt;/PointSymbolizer&gt;     &lt;/Rule&gt; &lt;/FeatureTypeStyle&gt;   My question is: Is there any better solution that is more dynamic? Recurrence relation for number of ternary strings that contain two consecutive zeros The question is: Find a recurrence relation for number of ternary strings of length n that contain two consecutive zeros.    I know for ternary strings with length one, there are 0. For a length of 2, there is just 1 (00), and for a length of 3, there are 5 (000,001,002,100,200).    I did a similar problem, finding a relation for the number of bit strings of length n with two consecutive zeros: $$a_n = a_{n-1} + a_{n-2} + 2^{n-2}$$    Since you can add "1" to the end of all the $a_{n-1}$ strings, "10" to all the $a_{n-2}$ strings, and "00" any string of size $n-2$.    For the ternary string problem, I'm pretty sure you would replace the $2^{n-2}$ with $3^{n-2}$, but confused about the other terms of the relation. My guess is that it would have the coefficient $2$ in front of the other terms, since you can add either $1$ or $2$ to the end of $a_{n-1}$ and either $01$ or $02$ at the end of $a_{n-1}$.    So I believe the answer for the relation is: $$a_n = 2a_{n-1} + 2a_{n-2} + 3^{n-2}$$    How does that look? Any hard-working student is a counterexample to "all students are lazy".  What are some simple counterexamples to "if random variables $X$ and $Y$ are uncorrelated then they are independent"? What exactly is the cause of RAM incompatibility? I'm looking at rather short QVL lists from manufacturers, and I'm wondering what is the underlying cause of RAM incompatibility aside from the obvious: Obvious Reasons for Incompatibility  RAM Generation (DDR, DDR2, DDR3, DDR4) Form Factor / pin count RAM Type (ECC vs Non-ECC, Registered vs not, Buffered vs not) Minimum speeds on a board that cannot adjust the memory frequency Non-standard voltage range on a board that cannot adjust the memory voltage Channel count (single vs dual vs quad) Bad or inoperable module Mismatched set  Not Obvious Reasons  Brand SKU Max Capacity Speed too high  As in, why can't motherboard manufacturers just list the specifications of the RAM they will accommodate, and support every memory chip of that category instead of listing specific SKUs from specific brands? What happens electrically/physically that causes boards to fail to POST / operate with RAM that is otherwise 'compatible' with all of the specifications of RAM that is on the QVL? How do you spell the following date:  December 6 (AmE)  6 December (BrE)  Do you spell this date as 'December six' or 'December the sixth' in American English?  And in British English, do you spell it as 'Six December' or 'The sixth of December'? How to solve the equation $\phi(n) = k$? Grand Prix Race Driver A has boon leading archrival B for a while by a steady 3 miles. Only 2 miles from the finish, driver A ran out of gas and decelerated thereafter at ta rate proportional to the square of his remaining speed. One mile later,driver A's speed was exactly halved.If driver B's speed remained constant,who won the race?  i have tried the set up the relation$d^2x\over dt^2$=$K ({dx\over dt})^2$ and integrate it but dont know how to do. Is there any cryptographic algorithm immune to side channel attacks based on scan chain? In VLSI point of view. Proving an integral equation. Let $P(x)$ be a degree $n$ polynomial with distinct roots $r_1, r_2, \cdots r_n$. Prove that   $$\displaystyle\sum_{i=1}^{n}\frac{P''(r_i)}{P'(r_i)}=0$$  My proof: We can equivalently rewrite the polynomial as $(x-r_1)(x-r_2)\cdots(x-r_n)$ and if we plug in the roots in the polynomial, we get that all of them are equal to $0$ so their first derivatives are equal to $1$ and then their second derivatives are equal to $0$ which means that all quotients are equal to $0$ and there for the sum is as well, $Q.E.D$  Don't show the solution please, but if you have a hint, feel free. Thank you. How to escape quotes in shell? I'm having trouble with escaping characters in bash. I'd like to escape single and double quotes while running a command under a different user. For the purposes of this question let's say I want to echo the following on the screen:  'single quote phrase' "double quote phrase"   How can I escape all the special chars, if I also need to switch to a different user:  sudo su USER -c "echo \"'single quote phrase' \"double quote phrase\"\""   Of course, this doesn't produce the right result. How can I check the version of the available package in the Ubuntu repositories without installing it? Covariance of a variable and a linear combination of other variables Let $X,A,B,C,D$ be time-series variables and the covariance between any two pairs of these are known.  Suppose we want to find $\textrm{cov}(X,aA + bB + cC + dD)$, where $a,b,c,d$ are constants.  Is there any way of doing this without expanding out $E[(X-E[X])(aA+......)]$? limit of $\lim\limits_{x \to \infty}((x+1)^a - x^a)$ Hello everybody, i couldn't figure out how to demonstrate this equation without L'Hopital i wonder if its possible.   $a \in (0,1)$ $\lim\limits_{x \to \infty}((x+1)^a - x^a) = 0$ How do I get $\cos{\theta} \lt \frac{\sin{\theta}}{\theta} \lt 1$? I want to use jQuery to parse RSS feeds. Can this be done with the base jQuery library out of the box or will I need to use a plugin? At the end of the new Guardians of the Galaxy Vol. 2 Trailer we meet Star Lord's father:                                  Dad appears to be human. But Peter Quill's mother said in the first film that his father was a      "being made of pure light".    What race (species?) is Star Lord's father in the MCU? Having 'Appendix A' instead of 'A Appendix' I would like to have my appendices labelled 'Appendix A', 'Appendix B', etc. However, when I use appendices in LaTeX (specifically llncs document class, downloadable at ), I instead get ''A Appendix', 'B Appendix' and so on. Is there any way to change that? More specifically, this is my minimal working example: \documentclass[envcountsame]{llncs}  \begin{document} \appendix \section{Appendix: Foo Bar} %I want this to appear as 'Appendix A: Foo Bar' \end{document} "Welcome to emergency mode!" Think it is a fsck problem My computer booted to a black screen with this error message.  Welcome to emergency mode! After logging in,type "journalctl -xb" to view    system logs, "systemctl reboot" to reboot, "systemctl default" or ^D to    try again to boot into default mode.   journalctl -xb snippet (what I think is wrong):  -- Unit systemd-fsckd.service has begun starting up. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: /dev/sdb1 contains a file system with errors, check forced. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: /dev/sdb1: Inodes that were part of a corrupted orphan linked list found. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: /dev/sdb1: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: (i.e., without -a or -p options) juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: fsck failed with error code 4. juli 09 15:40:16 kim-SSD-Sationary systemd-fsck[414]: Running request emergency.target/start/replace juli 09 15:40:16 kim-SSD-Sationary systemd[1]: systemd-fsck-root.service: main process exited, code=exited, status=1/FAILURE juli 09 15:40:16 kim-SSD-Sationary systemd[1]: Failed to start File System Check on Root Device. -- Subject: Unit systemd-fsck-root.service has failed -- Defined-By: systemd -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel --  -- Unit systemd-fsck-root.service has failed. --  -- The result is failed. juli 09 15:40:16 kim-SSD-Sationary systemd[1]: Unit systemd-fsck-root.service entered failed state. juli 09 15:40:16 kim-SSD-Sationary systemd[1]: systemd-fsck-root.service failed. juli 09 15:40:16 kim-SSD-Sationary systemd[1]: Starting Remount Root and Kernel File Systems... -- Subject: Unit systemd-remount-fs.service has begun start-up -- Defined-By: systemd -- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel   I ignored other errors like: ACPI PCC probe failed, nvidia not proprietary, etc.  I can access my PC by pressing Ctrl+D , but it is annoying. VPN server on Google Compute Engine with OpenVPN