We got a realatively high bounce rate today, because someone decided to spread some links using our mail server. The implementation looked like this: He used the registration form and planted a link in the firstname field, which appears in the email’s first line. Then he sent out like 1200 emails like this. And my question is what can we do to prevent this? We can use captcha for sure, but can we do more about it?
Tag: System
Why can’t I solve a system of four thirdorder partial differential equations using NDSolve?
I solve the problem of optimal control. First, I solve a system of two equations (with respect to the variables p, q, V, n) with already optimal conditions (Kopt and Sopt) to check whether it is possible to solve such a system at all. It turns out that everything is OK, but the nonlinear part of the equation cannot be discarded, it is important. I am using the NDSolve function with the StiffnessSwitching specification:
eq1 = D[n[x, t], t] + D[n[x, t]*V[x, t], x] == 0; eq2 = D[V[x, t], t] + Kopt[t]*x  2*(2*250^2)*Sopt[t]*Sin[k*x]*Cos[k*x]*k + V[x, t]*D[V[x, t], x] + g*D[n[x, t], x]  D[ D[Sqrt[n[x, t]], x, x]/(2*Sqrt[n[x, t]]), x] == 0; eqo1 = D[n[x, t], t] + D[n[x, t]*V[x, t], x] == 0; eqo2nl = D[V[x, t], t] + Kopt[t]*x  8*(2*250^2)*Sopt[t]*Sin[k*x]*Cos[k*x]*k + V[x, t]*D[V[x, t], x] + g*D[n[x, t], x]  ((D[n[x, t], x])^3  2*n[x, t]*D[n[x, t], x]*D[n[x, t], {x, 2}] + D[n[x, t], {x, 3}]*(n[x, t])^2)/(4*(n[x, t])^3) == 0; cond1 = n[x, t] == ((Sqrt[Kzero]/Pi)^(1/2))* Exp[0.5*Sqrt[Kzero]*x^2] /. t > 0; cond2 = n[x, t] == 0. /. x > 10; cond3 = n[x, t] == 0. /. x > 10; cond4 = V[x, t] == 0. /. t > 0; cond5 = V[x, t] == 0. /. x > 10; cond6 = V[x, t] == 0. /. x > 10; sol5 = NDSolve[{eqo1, eqo2nl, cond1, cond2, cond3, cond4, cond5, cond6}, {V, n}, {x, 10, 10}, {t, 0, Tv}, Method > {"StiffnessSwitching", Method > {"ExplicitRungeKutta", Automatic}}, AccuracyGoal > 1, PrecisionGoal > 1];
Next, I solve four equations in order to find the control parameter K (depends on q), while Sopt is still known. The initial conditions are the same and as banal as possible. Add two more equations and K[t] formula:
K[t_] := 1*Integrate[q[x, t]*x^2, {x, 10, 10}]; eqo3 = D[q[x, t], t] ==  n[x, t]*D[p[x, t], x]  V[x, t]*D[q[x, t], x]; eqo4 = D[p[x, t], t] + D[p[x, t], x]*V[x, t] + g*D[q[x, t], x] == 0;
The linearized system has a solution, but not a nonlinear one! There are many problems, including the order of the equation:
The spatial derivative order of the PDE may not exceed two.
I try to remove the third order derivative from the nonlinear part:
The maximum derivative order of the nonlinear PDE coefficients for \ the Finite Element Method is larger than 1. It may help to rewrite \ the PDE in inactive form.
Why does he even use only FEM now? Why was a nonlinear system of two equations solved normally? What should I do, help me, please.
Delta Search staying in system even after clean install
The picture is of a Dell KB522 multimedia keyboard. I have just made a clean installation of my system with windows 10 and installed chrome with ublock. By pressing the “internet” key (the multimedia key above F1), my default browser will open. Now, this is getting tricky.
If my default browser is Edge, it will open edge as many times as I press this internet key.
If my default browser is chrome, it will open chrome one time with a blank tab but as soon as I hit this internet key a second time, chrome will navigate to deltasearch dot com.
The drivers for the keyboard are the default keyboard driver from windows. Adware removal tool by TSA will find only the history entry and cache of deltasearch after I hit the internet key mutiple times in chrome.
Question is, where does it come from? Is my chrome/google account the problem?
This is already happening for years. I switched my setup several times over the years, even had a complete hardware switch where I went from AMD to Intel but the kind of keyboard is the same.
What is the “gauntlet” start system for character creation?
A while back in a stat discussion, someone mentioned that they used something called a “gauntlet” start for character creation. It was a post on Reddit, either for Kingmaker or regular Pathfinder.
I remember him saying that it made his stat array fixed to the point where he couldn’t even choose what went where, and he wanted advice on what class to pick as a result. Multiple people in the comments acknowledged its existence and a few even brought up their opinions on the system.
Sadly I can’t find anything on it, yet my curiosity is getting the best of me. There was a massive amount of equipment and unarmed strike stuff when I googled it, but in spite of excluding all that stuff I couldn’t find what I needed. (The post I saw originally did not mention equipment at any point, gauntlet or otherwise.)
What is the “gauntlet” start system for character creation?
Looking for a system: Epidemic Outbreak [closed]
What system could suit a shortterm survivalhorror campaign focused on a “realistic” epidemic outbreak scenario? (Realistic as in crunchy or grittyish, I know it’s pretty vague, sorry) I’m thinking about a quarantine setting, with the PC’s needing to adjust themselves to the situation (both psychologically and physically). Hunger and thirsty, crimes, state repression and (of course) the disease itself. (No zombies, please :p) Thanks in advance
Setting up secure personal system for managing sensitive data and high volume trading
So I’ve been mining and investing bitcoin for almost 5 years, and have reached the point where the volume of cryptocurrency I manage demands I take the time to create a secure cloud environment and set up a secure laptop. The fact that I handle some assets for family and close friends makes this need ever more pressing.
More generally, I am looking to establish a more secure digital presence, and believe an environment I can trust is the place to start. I should be able to trust this set up for any application (within reason, I’m not smuggling state secrets).
I have a beginner’s understanding of security principles, and experience in software. I am comfortable with less user friendly UIs and know my way around a terminal. I’m willing to put 1020 hours into setting this up, and am ready to familiarize myself with material if necessary. This is what I’m looking for:

Remote system with solid hard drive encryption. Nothing crazy, I’m thinking 256 bits, generating a random sequence of words that I will be able to memorize. I want to minimize the data that is left vulnerable when I connected, such that I don’t have to worry about theft after logging in.

Encrypted traffic and browsing from cloud system, an anonymous VPN or Tor would be ideal.
 Backup mechanism. I need to be able to access the system from any trusted computer, in the event of damage to the laptop.
 Firewall settings on laptop that allow only traffic to and from cloud environment. Essentially a close to cold system with only one connection, SSL.
 Disabled/nonexistent physical ports to protect from malicious software and USB killer type things. I am thinking a VM instance for the cloud side, but I have no experience in dealing with that stuff, so I need some guidance. On the physical end, I don’t really know where to start, and would very much appreciate any help.
I know this may sound like overkill, but rest assured I’m not a paranoid maniac, I just want to make sure security is not a concern.
Is fail2ban an intrusion prevention system?
I know what fail2ban does; it monitors the firewall logs and finds ip addresses that have too many failed logins to ssh; and then tells the firewall to drop packets from those addresses.
So is fail2ban an IPS?
Real cron killed my cron system. Only define( ‘ALTERNATE_WP_CRON’, true ); works
my host recommended me to disable wp cron for a real cron due to excessive executions.
the cron system broken immediately and scheduled tasks were not happening.
deleting real cron and turning on wp cron did not work.
through random luck, i tried define( ‘ALTERNATE_WP_CRON’, true ); and it worked.
having said so, i really want to revert back to the prior situation where normal wp cron works. it also messes up when all my links start to have &doing_wp_cron=
i have spent many hours and am desperate! appreciate your kind advice.
Can You Use Create a System using Glyph of Warding to Cast Teleporation Circle all 365 Days
Just curious if there’s some ingenious way to set up several glyph of warding spells to activate simultaneously. Some of them cast teleportation circle, Some of them to receive glyph of warding and store a casted teleportation circle.
In this way in 365 days you can enjoy a cheap efficient circle with the mats of but a few while exploring?
Is it possible to combine more than one memory request in one system call? If yes, what would be the impact of this on system performance?
And if not, what would be a suitable reason?