Tag: network

network flow – Integral solutions to circulation problem

Circulation problems are not just a generalization of max-flow, there is a reduction backwards as well. Suppose we have some directed graph $G = (V, E)$ with edge costs and capacities.

Any edge $u to v$ in $G$ with we can replace with two nodes $s, t$ and two edges $s to v$ and $u to t$ where one of the edges has the original cost/capacities and the other is free and unlimited. Call this graph $G'(e)$, where $e = uto v$ is the edge that was replaced.

Then if a flow with a certain cost exists in $G'(cdot)$, it must also exist as a circulation in $G$ with the same cost. Vice versa, if a circulation exists in $G$ and it uses edge $u to v$, then that flow also exists in $G'(uto v)$ with the same cost.

Therefore to solve the circulation problem we can pick an arbitrary edge $e$, calculate $G'(e)$ and use a traditional network flow algorithm to find the optimal flow. By the traditional arguments, this optimal flow is integral. We then pick another edge (avoiding edges that were part of a previous optimal flow) and repeat, keeping the best solution, until no more unknown edges are left.

Since in the worst case this adds a factor of $|E|$ to the complexity of the polynomial complexity, this is still polynomial. And of course the optimum from all integral flows found is itself integral.

Capture HTTP Referer in network traffic for whatsapp using Developer tools in Firefox

I’m using the Network traffic capture feature in developer tools in Firefox to see the network traffic generated when clicking on a link in a chat message on web version of whatsapp.

However, when I click on the link, it opens in a new tab on the browser but I can’t see the HTTP referer field in this case. How can I leverage developer’s tools network monitoring feature in Firefox to check this?

Thanks.

network – Is a vulnerable router less of an issue when placed “behind” a secure one?

Assume router A, which is secure with up to date firmware, and router B, which is less secure, with no longer updated firmware.

I have one router connected to the net socket (internet source), and the other router connected to the first one via WAN. Each router has a different router IP address, and two separate wifi access points.

From the perspective of security, is there any difference which router “comes first”, that is, which is the router that connects to the internet source and then “forwards” it?

Note: For the purposes of the question, assume no other difference in use. Both routers are accessed by devices I control and for similar purposes.

networking – Ubuntu 16.04: WiFi connection unavailable after shutdown (Network Unclaimed)

After restarting the machine, WiFi became unavailable.

I ran lshw -c network, and here is the output:

*-network UNCLAIMED
description: Ethernet controller
product: Ethernet Connection (7) I219-V
vendor: Intel Corporation
physical id: 1f.6
bus info: pci@0000:00:1f.6
version: 10
width: 32 bits
clock: 33MHz
capabilities: pm msi bus_master cap_list
configuration: latency=0
resources: memory:a1100000-a111ffff

I also ran lspci:

  • 00:00.0 Host bridge: Intel Corporation 8th Gen Core Processor Host
    Bridge/DRAM Registers (rev 07)
  • 00:02.0 VGA compatible controller: Intel Corporation Device 3e92
  • 00:12.0 Signal processing controller: Intel Corporation Cannon Lake
    PCH Thermal Controller (rev 10)
  • 00:14.0 USB controller: Intel Corporation Cannon Lake PCH USB 3.1
    xHCI Host Controller (rev 10)
  • 00:14.2 RAM memory: Intel Corporation Cannon Lake PCH Shared SRAM
    (rev 10)
  • 00:16.0 Communication controller: Intel Corporation Cannon Lake PCH
    HECI Controller (rev 10)
  • 00:17.0 SATA controller: Intel Corporation Cannon Lake PCH SATA AHCI
    Controller (rev 10)
  • 00:1f.0 ISA bridge: Intel Corporation Device a308 (rev 10)
  • 00:1f.3 Audio device: Intel Corporation Cannon Lake PCH cAVS (rev 10)
  • 00:1f.4 SMBus: Intel Corporation Cannon Lake PCH SMBus Controller
    (rev 10)
  • 00:1f.5 Serial bus controller (0c80): Intel Corporation Cannon Lake
    PCH SPI Controller (rev 10)
  • 00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection
    (7) I219-V (rev 10)

My machine is running on Ubuntu 16.04:

  • LSB
    Version: core-9.20160110ubuntu0.2-amd64:core-9.20160110ubuntu0.2-noarch:security-9.20160110ubuntu0.2-amd64:security-9.20160110ubuntu0.2-noarch
  • Distributor ID: Ubuntu
  • Description: Ubuntu 16.04.6 LTS
  • Release: 16.04
  • Codename: xenial

Any help would be much appreciated.

Thank you very much

network – My 2017 iMac is unable to print! But my old Mac Mini prints just fine! Any insights?

Today, something weird is happening: when I try to print (from TextEdit) from my iMac (2017, Retina 4k, running Mojave, printing to a network-connected HP 3055), it ACTS like the document printed, but nothing comes out. I tried cycling power on the printer; no joy. I tried rebooting; no joy. I tried removing and reinstalling the printer; No joy. I tried printing from other applications (Preview, OpenOffice); no joy. From the “HP LaserJet 3055…” application, I CAN’T print a test page, but I CAN reach the printer’s web interface, and print a PCL font list from it.

When I copy the document that started this whole mess over to my old Mini (running Mountain Lion, I think), it prints FINE from there. But still no joy printing from my Mini.

Any insights?

How to send a file from a network stream to dropbox?

I finally convinced someone willing to share his full archival node 5868GiB database for free (which now requires to be built in ram and thus requires 100000$ worth of ram in order to be built but can be run on an ssd once done).

However he want to send it only through sending a single tar file over raw tcp using a rather slow (400Mps) connection for this task.
I m needing to get it on dropbox and as a result, he don’t want to use the https://www.dropbox.com/request/(my upload key here) allowing to upload files through a web browser without a dropbox account (it really annoyed him that I talked about using an other method or compressing the database to the point he is on the verge of changing his mind about sharing it).
Because on my side, dropbox allows using 10Tib of storage for free during 30 days and I didn’t receive the required ssd yet (so once received I will be able to download it using a faster speed).

So the idea right now is to receive it through the method he want and pipe it using command line to the command for uploading it.

There are many tools for sending a file to dropbox. But all those I found requires downloading the whole file first or bufferring it in ram (even for fuse filesystems). I don t have the ram not even the disk space for that.

Is there even a curl command for uploading the file to my account or using the original https://www.dropbox.com/request/(my upload key here) link?

How to Start Smart Contract MLM like Forsage? – MLM & Network Marketing

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networking – How do you prevent a Windows Server 2019 network connection profile with no default gateway from reverting to “Public”

I am bringing up a new site and installing dual homed Windows 2019 RAS/Web servers. The interfaces on the DMZ must have a default gateway defined or they simply don’t work. The “internal” interfaces do not have a default gateway defined and this is fine once systems are attached to a domain controller

But while these systems are stand-alone, rebooting reverts the internal NICs profile to “public”. I, of course, change it back with Set-NetConnectionProfile. But next reboot and we are back where we started.

It is pretty darn annoying since I can no longer RDP to them! I am wondering if anyone has found a simple solution to this behavior.

Not interested in anything convoluted; no registry hacks or the like. As I say, once my domain controllers are up, this will take care of itself. But I deal with this incredibly moronic behavior (hope you are listening, Microsoft) every time I bring up a Windows site.

network – How does bitcoin find the block locator hashes in the leveldb database?

I am trying to understand how bitcoin core builds the list of block locator hashes needed for sendheaders and getheaders messages. I have looked on the wiki and I have seen that after the 10 most recent block hashes, it goes back exponentially until the genesis block.

So it seems that I have to get a block hash knowing its index in the blockchain. But how can bitcoin core find a block hash by its index? From my understanding leveldb lets you query data only by a key, and in this case the key is what I want.

Targeleon Affiliate Network (CPA,CPC,Push,Native,In-page,Pop,Calendar)

View attachment 259099

Targeleon is an Ad network with its own platform which was founded in 2014. We are working on CPA and CPC model. Our bank of offers counts more than 300 offers in various verticals. Advertisers can run their campaigns on our Self-Serve platform with the following Ad formats: Push, Native, In-Page, Pop, Calendar. We are looking for DSP / SSP partners to integrate via JSON / OpenRTB / XML