• 0 Posts
  • 114 Comments
Joined 1 year ago
cake
Cake day: July 2nd, 2023

help-circle
  • Almost. By virtue of being a smaller antenna, the 30 cm panel does not focus its energy as tightly as a larger (eg 60 cm) antenna. Likewise, a smaller antenna does not pick up (ie receive) as much energy as a larger antenna does. Thus, by using a 30 cm panel, less of the high energy from the opposite radio will reach the receiver, and that keeps the receiver from being damaged.

    In RF engineering, there is a careful balance between output power, antenna size/shape, environmental conditions, and desired link quality. Whoever built the radio link originally did not apparently perform the necessary calculation. I’m not an RF engineer, but for spanning a mere 50 meters, this 20 cm antenna with built-in radio should be more than sufficient for a basic link.


  • Normally, increased RF power is helpful to overcome interference or noise. Just like how normally, an automobile or airplane will be easier to operate if it has a bigger engine with more power.

    At some point, though, the extra RF or engine power is no longer beneficial but also isn’t harmful. And if you go significantly beyond that, then you end up in a region where the extra power is downright harmful and is actively working against you.

    Consider an automobile driving in a rainstorm. Having more power is bad, because the tires can lose grip more easily, leading to a crash. In an airplane that has gotten into a stall, applying power is the wrong solution and just aggravates the stall, which is not good.

    Here, adding more RF power is just cooking the other receiver like it’s a Thanksgiving turkey. The extra power is no longer helpful for making communications, and may be physically damaging the receiver.




  • Thank you for that detailed description. I see two things which are of concern: the first is the IPv6 network unreachable. The second is the lost IPv4 connection, as opposed to a rejection.

    So staring in order, the machine on the external network that you’re running curl on, does it have a working IPv6 stack? As in, if you opened a web browser to https://test-ipv6.com/ , does it pass all or most tests? An immediate “network is unreachable” suggests that external machine doesn’t have IPv6 connectivity, which doesn’t help debug what’s going on with the services.

    Also, you said that all services that aren’t on port 80 or 443 are working when viewed externally, but do you know if that was with IPv4 or IPv6? I use a browser extension called IPvFoo to display which protocol the page has loaded with, available for Chrome and Firefox. I would check that your services are working over IPv6 equally well as IPv4.

    Now for the second issue. Since you said all services except those on port 80, 443 are reachable externally, that would mean the IP address – v4 or v6, whichever one worked – is reachable but specifically ports 80 and 443 did not.

    On a local network, the norm (for properly administered networks) is for OS firewalls to REJECT unwanted traffic – I’m using all-caps simply because that’s what I learned from Linux IP tables. A REJECT means that the packet was discarded by the firewall, and then an ICMP notification is sent back to the original sender, indicating that the firewall didn’t want it and the sender can stop waiting for a reply.

    For WANs, though, the norm is for an external-facing firewall to DROP unwanted traffic. The distinction is that DROPping is silent, whereas REJECT sends the notification. For port forwarding to work, both the firewall on your router and the firewall on your server must permit ports 80 and 443 through. It is a very rare network that blocks outbound ICMP messages from a LAN device to the Internet.

    With all that said, I’m led to believe that your router’s firewall is not honoring your port-forward setting. Because if it did and your server’s firewall discarded the packet, it probably would have been a REJECT, not a silent drop. But curl showed your connection timed out, which usually means no notifications was received.

    This is merely circumstantial, since there are some OS’s that will DROP even on the LAN, based on misguided and improper threat modeling. But you will want to focus on the router’s firewall, as one thing routers often do is intercept ports 80 and 443 for the router’s own web UI. Thus, you have to make sure there aren’t such hidden rules that preempt the port-forwarding table.


  • I’m still trying to understand exactly what you do have working. You have other services exposed by port numbers, and they’re accessible in the form <user>.ducksns.org:<port> with no problems there. And then you have Jellyfin, which you’re able to access at home using https://jellyfin.<user>.duckdns.org without problems.

    But the moment you try accessing that same URL from an external network, it doesn’t work. Even if you use HTTP with no S, it still doesn’t connect. Do I understand that correctly?


  • I know this is c/programmerhumor but I’ll take a stab at the question. If I may broaden the question to include collectively the set of software engineers, programmers, and (from a mainframe era) operators – but will still use “programmers” for brevity – then we can find examples of all sorts of other roles being taken over by computers or subsumed as part of a different worker’s job description. So it shouldn’t really be surprising that the job of programmer would also be partially offloaded.

    The classic example of computer-induced obsolescence is the job of typist, where a large organization would employ staff to operate typewriters to convert hand-written memos into typed documents. Helped by the availability of word processors – no, not the software but a standalone appliance – and then the personal computer, the expectation moved to where knowledge workers have to type their own documents.

    If we look to some of the earliest analog computers, built to compute differential equations such as for weather and flow analysis, a small team of people would be needed to operate and interpret the results for the research staff. But nowadays, researchers are expected to crunch their own numbers, possibly aided by a statistics or data analyst expert, but they’re still working in R or Python, as opposed to a dedicated person or team that sets up the analysis program.

    In that sense, the job of setting up tasks to run on a computer – that is, the old definition of “programming” the machine – has moved to the users. But alleviating the burden on programmers isn’t always going to be viewed as obsolescence. Otherwise, we’d say that tab-complete is making human-typing obsolete lol



  • Another wonderful post to read, but once again, I’m in shock as to what the Australian frequency regulator seemingly doesn’t do. Perhaps it’s a tad unfair to compare ACMA to the American FCC – the latter well-recognized throughout the world for their (often counterfeited) certification mark – but it seems like ACMA is dropping the ball.

    Ubiquiti is probably the top producer outside of China for point-to-point WiFi-based equipment, so I have to imagine that other similar Western national frequency regulators to the FCC have the same demands upon Ubiquiti, such as to submit certification test reports from an RF lab. So either ACMA doesn’t request this before approving equipment to be sold in the country, or they don’t review test result and rely on other national regulator’s approvals, and that they don’t conduct spot testing on their own.

    All of those prospects are unfortunate. But I suppose if the national carrier is adjacent to the 900 MHz ISM band – I’m assuming Australia has this ISM band for unlicensed use? – that’s going to be rough no matter what.


  • It’s also worth noting that switching from ANSI to ISO 216 paper would not be a substantial physical undertaking, as the short-side of even-numbered ISO 216 paper (eg A2, A4, A6, etc) is narrower than for ANSI equivalents. And for the odd-numbered sizes, I’ve seen Tabloid-size printers in America which generously accommodate A3.

    For comparison, the standard “Letter” paper size (aka ANSI A) is 8.5 inches by 11 inches. (note: I’m sticking with American units because I hope Americans read this). Whereas the similar A4 paper size is 8.3 inches by 11.7 inches. Unless you have the rare, oddball printer which takes paper long-edge first, this means all domestic and small-business printers could start printing A4 today.

    In fact, for businesses with an excess stock of company-labeled #10 envelopes – a common size of envelope, measuring 4.125 inches by 9.5 inches – a sheet of A4 folded into thirds will still (just barely) fit. Although this would require precision folding, that’s no problem for automated letter mailing systems. Note that the common #9 envelope (3.875 inches by 8.875 inches) used for return envelopes will not fit an A4 sheet folded in thirds. It would be advisable to switch entirely to A series paper and C series envelopes at the same time.

    Confusingly, North America has an A-series of envelopes, which bear no relation to the ISO 216 paper series. Fortunately, the overlap is only for the less-common A2, A6, and A7.

    TL;DR: bring reams of A4 to the USA and we can use it. And Tabloid-size printers often accept A3.


  • My last post didn’t substantially address smaller ISPs, and from your description, it does sound like your ISP might be a smaller operator. But essentially, on the backend, a smaller ISP won’t have the customer base to balance their traffic in both directions. But they still need to provision for peak traffic demand, and as you observed, that could mean leaving capacity on the table, err fibre. This is correct from a technical perspective.

    But now we touch up on the business side of things again. The hypothetical small ISP – which I’ll call the Retail ISP, since they are the face that works with end-user residential customers – will usually contract with one of more regional ISPs in the area for IP transit. That is, upstream connectivity to the broader Internet.

    It would indeed be wasteful and expensive to obtain an upstream connection that guarantees 40 Gbps symmetric at all times. So they don’t. Instead, the Retail ISP would pursue a bustable billing contract, where they commit to specific, continual, averaged traffic rates in each direction, but have some flexibility to use more or less than that commited value.

    So even if the Retail ISP is guaranteeing each end-user at least 40 Gbps download, the Retail ISP must write up a deal with the Upstream ISP based on averages. And with, say, 1000 customers, the law of averages will hold true. So let’s say the average rates are actually 20 Gbps down/1 Gbps up.

    To be statistically rigorous though, I should mention that traffic estimation is a science, with applicability to everything from data network and road traffic planning, queuing for the bar at a music venue, and managing electric grid stability. Looking at historical data to determine a weighed average would be somewhat straightforward, but compensating for variables so that it can become future-predictive is the stuff of statisticians with post-nominative degrees.

    What I can say though, from what I remember in calculus at uni, is that if each end-user’s traffic rates are independent from other end-users (a proposition that is usually true but not necessarily at all times of day), then the Central Limit Theorem states that the distribution of the aggregate set of end-users will approximate a normal distribution (aka Gaussian, or bell curve), getting closer for more users. This was a staggering result when I first learned it, because it really doesn’t matter what each user is doing, it all becomes a bell curve in the end.

    The Retail ISP’s contract with the Upstream ISP probably has two parts: a circuit, and transit. The circuit is the physical line, and for the given traffic, probably a 50 Gbps fibre connection might be provisioned for lots of burstable bandwidth. But if the Retail ISP is somewhat remote, perhaps a microwave RF link could be set up, or leased from a third-party. But we’ll stick with fibre, as that’s going to be symmetrical.

    As a brief aside, even though a 40 Gbps circuit would also be sufficient, sometimes the Upstream ISP’s nearby equipment doesn’t support certain speeds. If the circuit is Ethernet based, then a 40 Gbps QSFP+ circuit is internally four 10 Gbps links bundles together on the same fibre line. But supposing the Upstream ISP normally sells 200 Gbps circuits, then 50 Gbps to the Retail ISP makes more sense, as a 200 Gbps QSFP56 circuit is internally made from four 50 Gbps, which oftentimes can be broken out. The Upstream and Retail ISPs need to agree on the technical specs for the circuit, but it certainly must provide overhead beyond the averages agreed upon.

    And those averages are captured in the transit contract, where brief exceedances/underages are not penalized but prolonged conditions would be subject to fees or even result in new contract negotiations. The “waste” of circuit capacity (especially upload) is something both the Retail ISP (who saves money, since guaranteed 50 Gbps would cost much more) and the Upstream ISP willingly accept.

    Why? Because the Upstream ISP is also trying to balance the traffic to their upstream, to avoid fees for imbalance. So even though the Retail ISP can’t guarantee symmetric traffic to the Upstream ISP, what the Retail ISP can offer is predictability.

    If the Upstream ISP can group the Retail ISP’s traffic with a nearby data center, then that could roughly balance out, and allow them to pursue better terms with the subsequent higher tier of upstream provider.

    Now we can finally circle back on why the Retail ISP would decline to offer end-users some faster upload speeds. Simply put, the Retail ISP may be aware that even if they offer higher upload, most residential customers won’t really take advantage of it, even if it was a free upgrade. This is the reality of residential Internet traffic. Indeed, the unique ISPs in the USA offering residential 10 Gbps connections have to be thoroughly aware that even the most dedicated of, err, Linux ISO afficionados cannot saturate that connection for more than a few hours per month.

    But if most won’t take advantage of it, then that shouldn’t impact the Retail ISP’s burstable contract with the Upstream ISP, and so it’s a free choice, right? Well, yes, but it’s not the only consideration. The thing about offering more upload is that while most customers won’t use it, a small handful will. And maybe those customers are the type that will complain loudly if the faster upload isn’t honored. And that might hurt Retail ISP’s reputation. So rather than take that gamble through guaranteeing faster upload for residential connections, they’d prefer to just make it “best effort”, whatever that means.

    EDIT: The description above sounds a bit defeatist for people who just want faster upload, since it seems that ISPs just want to do the bare minimum and not cater to users who are self-hosting, whom ISPs believe to be a minority. So I wanted to briefly – and I’m aware that I’m long winded – describe what it would take to change that assumption.

    Essentially, existing “average joe” users would have to start uploading a lot more than they are now. With so-called cloud services, it might seem that upload should go up, if everyone’s photos are stored on remote servers. But cloud services also power major sites like Netflix, which are larger download sources. So net-net, I would guess that the residential customer’s download-to-upload ratio is growing wider, and isn’t shrinking.

    It would take a monumental change in networking or computer or consumer demand to reverse this tide. Example: a world where data sovereignty – bonafide ownership of your own data – is so paramount that everyone and their mother has a social-media server at home that mutually relays and amplifies viral content. That is to say, self-hosting and upload amplification.


  • Historically, last-mile technologies like dial-up, DSL, satellite, and DOCSIS/cable had limitations on their uplink power. That is, the amount of energy they can use to send upload through the medium.

    Dial-up and DSL had to comply with rules on telephone equipment, which I believe limited end-user equipment to less power than what the phone company can put onto the wires, premised on the phone company being better positioned to identify and manage interference between different phone lines. Generally, using reduced power reduces signal-to-noise ratio, which means less theoretical and practical bandwidth available for the upstream direction.

    Cable has a similar restriction, because cable plants could not permit end-user “back feeding” of the cable system. To make cable modems work, some amount of power must be allowed to travel upstream, but too much would potentially cause interference to other customers. Hence, regulatory restrictions on upstream power. This also matched actual customer usage patterns at the time.

    Satellite is more straightforward: satellite dishes on earth are kinda tiny compared to the bus-sized satellite’s antennae. So sending RF up to space is just harder than receiving it.

    Whereas fibre has a huge amount of bandwidth, to the point that when new PON standards are written, they don’t even bother reusing the old standard’s allocated wavelength, but define new wavelengths. That way, both old and new services can operate on the fibre during the switchover period. So fibre by-default allocates symmetrical bandwidth, although some PON systems might still be closer to cable’s asymmetry.

    But there’s also the backend side of things: if a major ISP only served residential customers, who predominantly have asymmetric traffic patterns, then they will likely have to pay money to peer with other ISPs, because of the disparity. Major ISPs solve this by offering services to data centers, which generally are asymmetric but tilted towards upload. By balancing residential with server customers, the ISP can obtain cheaper or even free peering with other ISPs, because symmetrical traffic would benefit both and improve the network.



  • I will admit that my familiarity with private law outside the USA is almost non-existent, except for what I skimmed from the Wikipedia article for the Inquisitorial system. So I had assumed that private law in European jurisdictions would follow the same judge-intensive approach. Rereading the article more closely, I do see that it really only talks about criminal proceedings.

    But I did some more web searching, and found this – honestly, extremely convenient – article comparing civil litigation procedure in Germany and California (the jurisdiction I’m most familiar with; IANAL). The three most substantial differences I could identify were the judge’s involvement in: serving papers, discovery, and depositions.

    Serving legal notice is the least consequential difference between California and Germany, but it seems that the former allows any qualified adult to chase down the respondent (ie person being sued) and deliver the notice of a lawsuit – hence the trope of yelling “you have been served” and then throwing a stack of papers at someone’s porch – on behalf of the complainant (person who filed the lawsuit). Whereas German courts take up the role themselves for notifying the complainant. Small difference, but notable.

    In Germany, the court, and not the plaintiff, is required to serve the complaint on the defendant without undue delay, which is usually immediately after it has been filed with the court.

    Next, discovery and pleadings in Germany appear to be different from the California custom. It seems that German courts require parties to thoroughly plead their positions first, and only afterwards will discovery begin, with the court deciding what topics can be investigated. Whereas California allows parties to make broad assertions that can later be proven or disproven during discovery. This is akin to throwing spaghetti at the wall and seeing what sticks, and a big reason this is done is because any argument that isn’t raised during trial cannot be reargued during a later appeal.

    I believe that discovery in California and other US States can get rather invasive, as each party’s lawyers are on a fact-finding mission where the truth will out. The general limitation on the pleadings in California is that they still must be germane to the complaint and at least be colorable. This obviously leads to a lot of pre-trial motions, as the targeted party will naturally want to resist a fishing expedition during discovery.

    Lastly, depositions in Germany involve the judge(s) a lot more than they would in California. Here, depositions are off-site from the court and conducted by the deposing party, usually video-taped and with all attorneys present, plus a privately hired stenographer, with the deposing attorney asking questions. Basically, after a deposition order is granted by the judge, the judge isn’t involved unless during the deposition, the process is interrupted in a way that would violate the judge’s order. But the solution to that is to simply phone the judge and ask for clarification or a new order to force the deposition to continue.

    Whereas that article describes the German deposition process as always occuring in court, during trial, and with questions asked by the judge(s). The parties may suggest certain questions by way of constructing arguments which require the judge(s) to probe in a particular direction. But it’s not clear that the lawyers get to dictate the exact questions asked.

    In contrast, depositions in Germany are conducted by the judge or the panel of judges and only during trial.

    I grant you that this is just an examination of the German court proceedings for private law. And perhaps Germany may be an outlier, with other European counterparts adopting civil law but with a more adversarial flavor for private law. But I would say that for Germany, these differences indicate that their private law is more inquisitorial overall, in stark contrast to the California or USA adversarial procedure for private litigation.



  • I am usually not wont to defend the dysfunction presently found in the USA federal (and state-level) judiciary, but I think this comparison to the German courts requires a bit more context. Generally speaking, the USA federal courts and US States adopt the adversarial system, originally following the English practice in both common law and equity. This means the judge takes on a referee role, and a plaintiff and a defendant will make their best, most convincing arguments.

    I should clarify that “common law” in this context refers to the criminal matters (akin to public law), and “equity” refers to person-versus-person disputes (akin to private law), such as contracts.

    For the adversarial system to work, the plaintiff and defendant need to be sufficiently motivated (and nowadays, well-monied) to put on good arguments, or else they’re just wasting the court’s time. Hence, there is a requirement (known as “standing”) where – grossly oversimplifying – the plaintiff must be the person with the most to gain, and the defendant must be the person with the most to lose. They are interested parties who will argue vigorously.

    Of course, that’s legal fiction, because oftentimes, a defendant might be unable to able to afford excellent legal counsel. Or plaintiffs will half-ass or drag out a lawsuit, so that it’s more an annoyance to the opposite party.

    In an adversarial system, it is each party’s responsibility to obtain subject-matter experts and their opinions to present to the court. The judge is just there to listen and evaluate the evidence – exception: criminal trials leave the evaluation of evidence to the jury.

    Why is the USA like this? For the USA federal courts, it’s because it’s part of our constitution, in the Case or Controversy Clause. One of the key driving forces for drafters of the USA Constitution was to restrict the powers of government officials and bureaucrats, after seeing the abuses committed during the Colonial Era. The Clause above is meant to constrain the unelected judiciary – which otherwise has awe-inducing powers such as jailing people, undoing legislation, and assigning wardship or custody of children – from doing anything unless some controversy actually needed addressing.

    With all that history in mind, if the judiciary kept their own in-house subject-matter experts, then that could be viewed as more unelected officials trying to tip the scale in matters of science, medicine, computer science, or any other field. Suddenly, landing a position as the judiciary’s go-to expert could have broad reaching impacts, despite no one in the federal judiciary being elected.

    In a sense, because of the fear of officials potentially running amok, the USA essentially “privatizes” subject matter experts, to be paid by the plaintiff or defendant, rather than employed by the judiciary. The adversarial system is thus an intentional value judgement, rather than “whoopsie” type of thing that we walked into.

    Small note: the federal executive (the US President and all the agencies) do keep subject matter experts, for the limited purpose of implementing regulations (aka secondary legislation). But at least they all report indirectly to the US President, who is term-limited and only stays 4 years at a time.

    This system isn’t perfect, but it’s also not totally insane.


  • I’m in awe why your frequency spectrum regulator doesn’t have the capability to do radio directions finding to identify the interference source, rather than process-of-elimination of licensed and unlicensed users colocated on a tower. That just seems inefficient.

    Here in the USA, although the FCC doesn’t often roll their trucks for every single complaint, an ongoing issue like broad interference to a licensed user would tend to result in an agent being dispatched to investigate. And the FCC Enforcement Division is known for fines starting at $10,000 and going upward.

    Another entity that also has RDF capabilities tends to be the electric utilities here, as they get a lot of complaints – rightly or wrongly – for HF and VHF interference from their equipment.



  • Looking at the diagram, I don’t see any issue with the network topology. And the power arrangement also shouldn’t be a problem, unless you require the camera/DVR setup to persist during a power cut.

    In that scenario, you would have to provide UPS power to all of: the PoE switch, the L3 switch, and the NVR. But if you don’t have such a requirement, then I don’t see a problem here.

    Also, I hope you’re doing well now.