## windows – How to trace “The operating system is not presently configured to run this application.”?

I have a very old application which I need to run on a newer Windows system. And that application does not start with the dreaded:

The operating system is not presently configured to run this application.

Googling for this problem brings up lots of very specific issues with specific apps and the solutions are just shots in the dark or super specific things with specific versions of Windows, Office, etc.

But I’d like to know if there is a way to trace the start-up of such applications to find out what specifically is wrong so I can fix it.

Most likely it’s some DLLs are missing. On Unix I have ldd and I can find out what shared libraries they need and which ones are present vs. missing. Is there an ldd equivalent?

And is there some dtrace equivalent where, if the issue is not just a missing DLL, we can see where this error occurs more or less to get a clue what misconfiguration might exist?

## postgresql – How do I trace Postgres Frontend and Backend messages?

As per my understanding when we execute a Command or Query. Postgres Client sends Frontend Message and in return gets the response in the Backend Message format.

How do I capture and check these messages on Linux box?

For e.g. let’s say I am executing the below command via psql client

I believe the client creates StartupMessage

is there a way to trace down this interaction? considering server and client are running on the same machine.

## fa.functional analysis – Elliptic Estimates with Trace

Say $$Omegasubsetmathbb{R}^3$$ is a bounded domain with smooth boundary. Let $$Bin C^infty(barOmega)$$, and consider the set $$X={u in H^1(Omega)|u_{|partialOmega}=B_{|partialOmega} text{ in the sense of traces}}$$. Due to the Sobolev inequality, we know that $$H^1(Omega)$$ is continuously embedded in $$L^p(Omega)$$ for $$pin(1,6)$$. Say we wanted to prove, for fixed $$pin(1,6)$$, that there exists $$C$$ such that for all $$uin X$$, we have
$$|u|_{L^p}le C(|nabla u|_{L^2}+|B|_{L^infty}).$$
A pretty standard proof probably goes something like this: assume not, then there exists a sequence of functions $$u_nin X$$ such that
$$frac{1}{n}|u_n|_{L^p}ge|nabla u_n|_{L^2}+|B|_{L^infty}.$$
Defining
$$v_n=u_n/|u_n|_{L^p}$$
we have that $$|v_n|_{L^p}=1$$ for each $$n$$ and
$$frac{1}{n}ge |nabla v_n|_{L^2}+|B|_{L^infty}/|u_n|_{L^p}.$$
From this, we see, in particular, that $$v_n$$ is bounded in $$H^1$$. Therefore if $$pin(1,6)$$, then due to Rellich’s theorem, we have that there exists $$vin H^1$$ such that (after passing to a subsequence) $$v_nto v$$ weakly in $$H^1$$ and strongly in $$L^p$$. In addition, since $$|nabla v_n|_{L^2}to 0$$, we conclude that $$v$$ is constant.

On the other hand, by definition, $${v_n}_{|partialOmega}=(B/|u_n|_{L^p})_{|partialOmega}$$. But we see from the above inequality that $$|B|_{L^infty}/|u_n|_{L^p}$$ must also go to zero as $$nto infty$$. Therefore, by the continuity of the trace operator from $$H^1(Omega)$$ to $$H^frac{1}{2}(partialOmega)$$ and the weak convergence of $$v_n$$ to $$v$$ in $$H^1$$, we have $$v_{|partialOmega}=0$$. Therefore, since we already know $$v$$ must be constant, we conclude that $$vequiv 0$$. However, since $$v_nto v$$ strongly in $$L^p$$, we have $$|v|_{L^p}=1$$, a contradiction.

OK, assuming that’s all more or less fine, notice that the contradiction comes for the fact that we were able to extract a subsequence of $$v_n$$ that converges strongly in $$L^p$$, and this followed from Rellich.

My question is, what about the case of $$p=6$$? The embedding $$H^1subset L^6$$ is continuous, but not compact, so we’d only be able to extract a subsequence $$v_n$$ that converges weakly in $$L^6$$. Then, in the last line of the proof above, we’d only be able to conclude $$|v|_{L^6}le 1$$, so no contradiction. I’m inclined to believe that the statement still holds for $$p=6$$, but how does one prove it?

Edit: it occurred to me soon after writing this that we could simply say that from the Sobolev inequality we have
$$|u|_{L^6}le C(|nabla u|_{L^2}+|u|_{L^2})$$
at which point we can bound
$$|u|_{L^2}le C(|nabla u|_{L^2}+|B|_{L^infty})$$
in the way that I explained above. And this gives me what I need. I guess this is fine, but a small part of me still wonders if there’s a “direct” proof…

## users – Removing all trace of member profiles

I am working on a site that deals with extremely sensitive and personal topics of personal health. As such, it is necessary that having a user account on the site is completely confidential with zero traces left on the public-facing site.

Aside from a few admin tools, all plugins used will be written by me (so no leakage via plugins should happen); likewise, I will be creating a custom theme (all other themes removed). I can therefore be relatively sure that content does not show user links aside from comments on the blog (one of the areas where I’m struggling).

What personal information is required (and some is needed) I plan to store encrypted.

I’ve blocked enumerable profile links – stuff like example.com/?author=42 just gets yeeted away via .htaccess. I’m assuming I can do the same for the fancy permalink version (I’ve not looked into that yet).

I’ve looked at adding a theme function to detect /author/* pages and doing some sort of if statement that looks at if the member is logged in and/or if the page type is a member profile. However, that does not stop the member/author profile pages from existing (something I’d like to just outright remove). Also, as I said, this would not stop member comments on the blog from leaking information via the comments link – I’m struggling with that part.

I’m okay with the idea of building a firewall of .htaccess and code level redirects away from public profiles as well as redacting it in all theme parts. What worries me is that even if example.com/author/yourname cannot easily be reached and displays “404 – no such page” it still “exists” and the URL itself leaks information.

I figure there must be a way to hook the permalink generation and create a garbage URL even if I do not know how to do so yet.

Which hooks and filters do I need to examine to remove any final traces of the members from the public site (while still having user accounts)?

Is there anything else I should know, try, or look at that I have not covered here? Anything else that can point me in the right direction would be greatly appreciated.

## Best way to trace possible root cause of card fraud?

I recently had a fraudulent transaction on my debit card (in the UK, where I am based). Having blocked the card, my main concern is to determine how much information has been stolen and how?

As this was an online transaction, the fraudster may have needed only superficial information regarding my card to complete the transaction e.g., expiry date, long card number and security code. These details could, theoretically, have been stolen while I used my card in person (at an ATM or while paying for goods) or they could have been stolen via hacking or phishing of myself or someone who has my details, which I would view as a lot more nefarious.

When I reported the transaction to my bank, I didn’t ask whether other auxiliary details were used in the transaction e.g. my DoB, telephone number, security questions which may have been indicative of a wider problem.

I have no reason to believe that I am personally the victim of a hack or phishing. I use anti-virus and am careful with online transactions.

My questions are:

(1) Is it normal for banks to be able to give more information about a specific fraudulent transaction to their customers to help them understand how much information has been compromised?

(2) What is the best way to approach finding how much information may have been stolen and how?

## fa.functional analysis – Derivative of trace

Consider two positive-semi definite trace class operators $$T_1, T_2$$ of unit trace.

Let $$T(lambda):=T_1 + lambda(T_2-T_1)$$ be the convex combination of the two.

We then study $$f(lambda) := operatorname{tr}(T(lambda)log(T(lambda)).$$

I conjecture that $$f'(lambda) = operatorname{tr}(P_{operatorname{ker}(T_1)} T_2)log(lambda)+mathcal O(1),$$ where $$P_V$$ is the projection on the space $$V$$.

I actually did not want to use the spectral theorem (intentionally) to show this but rather go via Jacobi’s formula

$$e^{ operatorname{tr}(T(lambda)log(T(lambda))} = operatorname{det}(e^{T(lambda)}T(lambda))$$
since this way everything looks much more smooth.

Are there any elementary proofs of this? Or is my conjecture even wrong?

## How can i trace a transaction where my bitcoin has been withdrawn from my paper wallet?

My bitcoin has been stolen from my paper wallet, can I track where its gone and is it possible to do so with my paper wallet?

## linear algebra – Loss function for matrix with fixed trace

I have a matrix $$P in mathbb{R}^{n times m}$$ where $$n gg m$$ and each row of $$P$$ has norm $$1$$.

It is not hard to see that the $$P^T P$$ has a fixed trace $$n$$.

I am try to find a loss function to push $$P^T P$$ to be a scaled identity matrix $$frac{n}{m} I$$

Currently, I found out that minimize either $$- log det (P^T P)$$ or $$mathrm{Trace}(P^T P P^T P)$$ will get to the optimal point, but I am wondering is there a better loss function I could use and how the gradient will be like?

## postfix – How to Trace Who was Using my Mail Relay on Spamming?

I have a Postfix mail relay server running as Exchange smarthost as well as hosting another mail locally.

Last week I observed an attack on this server, someone is using it to send massive emails to different destinations.

I can’t find out where it is connected from and the “from” address is also masked.

Below is the mail logs:

Apr 16 06:29:10 mail.xxx.com postfix/qmgr(25497): EC5A91D727: from=<>, size=3096, nrcpt=1 (queue active)
Apr 16 06:29:10 mail.xxx.com postfix/bounce(12183): B37D31D6FA: sender non-delivery notification: EC5A91D727
Apr 16 06:29:10 mail.xxx.com postfix/qmgr(25497): B37D31D6FA: removed
Apr 16 06:29:11 mail.xxx.com postfix/smtp(12164): 1A9B71D801: to=<xxx@inver**.com>, relay=inver**.com(164.138.x.x):25, delay=50, delays=39/0/6.7/5, dsn=2.0.0, status=sent (250 OK id=1lX6jh-000875-TC)
Apr 16 06:29:11 mail.xxx.com postfix/qmgr(25497): 1A9B71D801: removed
Apr 16 06:29:11 mail.xxx.com postfix/smtp(11990): 3BEAB1D9C3: to=<xxx@tms**.pl>, relay=tms**.pl(194.181.x.x):25, delay=49, delays=37/0/6.7/5.4, dsn=2.0.0, status=sent (250 OK id=1lX6ji-000469-QT)
Apr 16 06:29:11 mail.xxx.com postfix/qmgr(25497): 3BEAB1D9C3: removed
Apr 16 06:29:12 mail.xxx.com postfix/smtp(12954): 418621D80D: to=<xxx@medi**.com.cn>, relay=mxw**.com(198.x.x.x):25, delay=51, delays=38/0/8.5/4.5, dsn=5.0.0, status=bounced (host mxw.mxhichina.com(198.11.189.243) said: 551 virus infected mail rejected (in reply to end of DATA command))
Apr 16 06:29:12 mail.xxx.com postfix/cleanup(7936): 6711A1D7B7: message-id=<20210415182912.6711A1D7B7@mail.xxx.com>
Apr 16 06:29:12 mail.xxx.com postfix/bounce(12184): 418621D80D: sender non-delivery notification: 6711A1D7B7
Apr 16 06:29:12 mail.xxx.com postfix/qmgr(25497): 418621D80D: removed
Apr 16 06:29:12 mail.xxx.com postfix/qmgr(25497): 6711A1D7B7: from=<>, size=2554, nrcpt=1 (queue active)
Apr 16 06:29:12 mail.xxx.com postfix/smtp(11499): 65E4C1D95F: to=<xxx@an**.com>, relay=aspmx.l.google.com(172.217.x.x):25, delay=51, delays=38/0/6.3/6.7, dsn=5.7.0, status=bounced (host aspmx.l.google.com(172.217.194.27) said: 552-5.7.0 This message was blocked because its content presents a potential 552-5.7.0 security issue. Please visit 552-5.7.0  https://support.google.com/mail/?p=BlockedMessage to review our 552 5.7.0 message content and attachment content guidelines. z63si3810735ybh.300 - gsmtp (in reply to end of DATA command))
Apr 16 06:29:12 mail.xxx.com postfix/cleanup(10468): 705F91D801: message-id=<20210415182912.705F91D801@mail.xxx.com>
Apr 16 06:29:12 mail.xxx.com postfix/smtp(11996): F05911DBCA: to=<xxx@maq**.ae>, relay=maq**.protection.outlook.com(104.47.x.x):25, delay=36, delays=27/0/3.1/6, dsn=2.6.0, status=sent (250 2.6.0 <20210415112836.BE31E4C0C57EAA1B@alshirak.com> (InternalId=93338229282509, Hostname=DB8PR10MB2745.EURPRD10.PROD.OUTLOOK.COM) 933811 bytes in 3.322, 274.451 KB/sec Queued mail for delivery)
Apr 16 06:29:12 mail.xxx.com postfix/qmgr(25497): F05911DBCA: removed
Apr 16 06:29:12 mail.xxx.com postfix/bounce(12183): 65E4C1D95F: sender non-delivery notification: 705F91D801
Apr 16 06:29:12 mail.xxx.com postfix/qmgr(25497): 65E4C1D95F: removed

How to check where is the attack source? Is there a way to limit only a specific range of domains that can be used for mail relay?

I’m not a Postfix professional, so any suggestions/advises would be appreciated.

## Lost my bitcoin four years ago, trying to trace the wallet

four years ago I purchased 0.43 Bitcoin from localbitcoin.com.
I received the Bitcoin and sent it through a bitmixer to one of my wallets.
I checked all wallets and nothing was ever received.
I have the address I sent it too and the txid number.
Can anyone help locate my money? I will pay if this is possible.