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Search - "network time protocol"
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Soms week ago a client came to me with the request to restructure the nameservers for his hosting company. Due to the requirements, I soon realised none of the existing DNS servers would be a perfect fit. Me, being a PHP programmer with some decent general linux/server skills decided to do what I do best: write a small nameservers which could execute the zone transfers... in PHP. I proposed the plan to the client and explained to him how this was going to solve all of his problems. He agreed and started worked.
After a few week of reading a dozen RFC documents on the DNS protocol I wrote a DNS library capable of reading/writing the master file format and reading/writing the binary wire format (we needed this anyway, we had some more projects where PHP did not provide is with enough control over the DNS queries). In short, I wrote a decent DNS resolver.
Another two weeks I was working on the actual DNS server which would handle the NOTIFY queries and execute the zone transfers (AXFR queries). I used the pthreads extension to make the server behave like an actual server which can handle multiple request at once. It took some time (in my opinion the pthreads extension is not extremely well documented and a lot of its behavior has to be detected through trail and error, or, reading the C source code. However, it still is a pretty decent extension.)
Yesterday, while debugging some last issues, the DNS server written in PHP received its first NOTIFY about a changed DNS zone. It executed the zone transfer and updated the real database of the actual primary DNS server. I was extremely euphoric and I began to realise what I wrote in the weeks before. I shared the good news the client and with some other people (a network engineer, a server administrator, a junior programmer, etc.). None of which really seemed to understand what I did. The most positive response was: "So, you can execute a zone transfer?", in a kind of condescending way.
This was one of those moments I realised again, most of the people, even those who are fairly technical, will never understand what we programmers do. My euphoric moment soon became a moment of loneliness...21 -
At college (UK) and taking a general IT course (databases, programming, networking) a friend suggested "We should make our own network protocol." (The only language we had covered at the time was Visual Basic)4
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Another incident which made a Security Researcher cry
[ NOTE : Check profile to read older incidents ]
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So this all started when I was at my home (bunked the office that day xD) and I got a call from a..... Let's call him Fella as I always do . So here we go . And yeah , our Fella is a SysAdmin .
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Fella - Hey man sup!
Me - Good going mate , bunked the office , weather's nice , gonna spend time with my girl today . So what's goinon?
Fella - Bruh my network sharing folders ain't working no more .
Me - Did you changed or modified anything?
Fella - Nope
Me - Okay , gimme your login creds lemme check .
Fella - Check your inbox *texts me the credentials*
*I logged in and what I'm seeing is that server runs on Windows2008R2 , checked the event logs , everything's fine and all of a sudden what I found is fucking embarrassing , this wise man closed SMB service*
Me - Did you closed SMB service?
Fella - Yeah
Me - You know what it does?
Fella - Yeah it's a protocol , I turned it off to protect the server from Wannacry .
Me - Fuckerrrr!!!!! Asshole dumbass you fuckin piece of Dodo's shit!! SMB is the service responsible for files and network sharing!!!
Fella - But....I just wanted protection
Me - 😭😭😭
*A long conversation continues with a lot of specially made words to decrease the rate of frustration which I used already*
Fella - Okay I'm turning it on .
Me - Go on....... Asshole
Fella - It worked! Thanks a lot bro
Me - Just leave me and my soul away from evil and hang up .
*Now the question is , who the hell gives them the post of SysAdmin? While thinking this question , I almost thought of committing suicide but then my girl came with coffee and my rubber duck*1 -
Last Monday I bought an iPhone as a little music player, and just to see how iOS works or doesn't work.. which arguments against Apple are valid, which aren't etc. And at a price point of €60 for a secondhand SE I figured, why not. And needless to say I've jailbroken it shortly after.
Initially setting up the iPhone when coming from fairly unrestricted Android ended up being quite a chore. I just wanted to use this thing as a music player, so how would you do it..?
Well you first have to set up the phone, iCloud account and whatnot, yada yada... Asks for an email address and flat out rejects your email address if it's got "apple" in it, catch-all email servers be damned I guess. So I chose ishit at my domain instead, much better. Address information for billing.. just bullshit that, give it some nulls. Phone number.. well I guess I could just give it a secondary SIM card's number.
So now the phone has been set up, more or less. To get music on it was quite a maze solving experience in its own right. There's some stuff about it on the Debian and Arch Wikis but it's fairly outdated. From the iPhone itself you can install VLC and use its app directory, which I'll get back to later. Then from e.g. Safari, download any music file.. which it downloads to iCloud.. Think Different I guess. Go to your iCloud and pull it into the iPhone for real this time. Now you can share the file to your VLC app, at which point it initializes a database for that particular app.
The databases / app storage can be considered equivalent to the /data directories for applications in Android, minus /sdcard. There is little to no shared storage between apps, most stuff works through sharing from one app to another.
Now you can connect the iPhone to your computer and see a mount point for your pictures, and one for your documents. In that documents mount point, there are directories for each app, which you can just drag files into. For some reason the AFC protocol just hangs up when you try to delete files from your computer however... Think Different?
Anyway, the music has been put on it. Such features, what a nugget! It's less bad than I thought, but still pretty fucked up.
At that point I was fairly dejected and that didn't get better with an update from iOS 14.1 to iOS 14.3. Turns out that Apple in its nannying galore now turns down the volume to 50% every half an hour or so, "for hearing safety" and "EU regulations" that don't exist. Saying that I was fuming and wanting to smack this piece of shit into the wall would be an understatement. And even among the iSheep, I found very few people that thought this is fine. Though despite all that, there were still some. I have no idea what it would take to make those people finally reconsider.. maybe Tim Cook himself shoving an iPhone up their ass, or maybe they'd be honored that Tim Cook noticed them even then... But I digress.
And then, then it really started to take off because I finally ended up jailbreaking the thing. Many people think that it's only third-party apps, but that is far from true. It is equivalent to rooting, and you do get access to a Unix root account by doing it. The way you do it is usually a bootkit, which in a desktop's ring model would be a negative ring. The access level is extremely high.
So you can root it, great. What use is that in a locked down system where there's nothing available..? Aha, that's where the next thing comes in, 2 actually. Cydia has an OpenSSH server in it, and it just binds to port 22 and supports all of OpenSSH's known goodness. All of it, I'm using ed25519 keys and a CA to log into my phone! Fuck yea boi, what a nugget! This is better than Android even! And it doesn't end there.. there's a second thing it has up its sleeve. This thing has an apt package manager in it, which is easily equivalent to what Termux offers, at the system level! You can install not just common CLI applications, but even graphical apps from Cydia over the network!
Without a jailbreak, I would say that iOS is pretty fucking terrible and if you care about modding, you shouldn't use it. But jailbroken, fufu.. this thing trades many blows with Android in the modding scene. I've said it before, but what a nugget!8 -
## building my own router
I hoped things would go more smoothly :)
Anyway, my new miniPC easily accepted CentOS 8 - no fuss here. And I've got to say - I love CentOS8 so far! Shell has amazing nifty tricks, UI (gnome3) is also snappy, video/audio/ethernet,.. everything works.
What I did NOT expect is hardware being off. Well okay, the price was low - it was obvious smth is not right. But still.. I decided to build my own router so that I could swap wifi card whenever I want. So that I could run my own network services in there. Turns out - the card swapping is not as easy as one might think.
I got the AX200 WiFi6 card for that very purpose. But once plugged in the OS can only see it's bluetooth module. Weird... What's even weirder is that even though the card is PCIe, the OS uses btusb module to talk to that device. What? USB?? emm.. What??
And there it is. After opening it up again I noticed that the mPCIe area is marked with a label: "USB WIFI / WWAN". USB? Does that mean this PCIe slot is wired into the USB bus? Not impossible I guess.
Googling for a "pcie wifi over usb" or smth like that brought me to one reddit (I think?) where someone wanted to build a DIY wifi mPCIe -> USB adapter and someone else adviced hime that (for some reason) at best he could only get bluetooth working (hey! just like me!). It's got to do smth with pcie channels and USB being too weak to handle all that load, or smth.. IDK, I'm not a HW guy.
Well that sucks then! I have a mPCIe slot that does not work as a PCIe. Shit! So I guess the best I could do is to plug back in the same wifi card that came with the device. It smells like 2003 - supports only g protocol. Fine, let's try that. Maybe I'll find a way to work around this mPCIe limitation later on (USB adapter or smth... except there are no USB WIFI6 dongles yet :( ). So I plug it back in and start turning it into a router. Disable NetworkManager, configure static NCs' settings, install dhcpd, hostapd, bind and others. Looks like all is done! Now it's time to start it all. systemctl start hostapd --> FAILED. wtf? journalctl says it could not initialize a driver. umm okay? Why? Forums say I should airodump-ng check and kill whatever's using that device. Fine. airodumo reveals avahi and wpa_suppl are still using it. kill, kill, GOTTA KILL 'EM ALL!! Starting hostapd again -- same shit... wtf?
iw list
My gawd... That shitty network card does not even support AP mode :( I mean.. My USB wifi dongle for 2€ supports 2x more modes, is faster, has better range and is easier to work with than this old tart!
Yeah. That was an interesting day. When enfironment engineers break my testing environments at work I'm glad I have where to spend my time now.
BTW any ideas how to bypass this mPCIe nonsense? Come on, there are USB GPUs out there.. Why can't they make a USB (or dual-USB if they really need to) mPCIe adapter?8 -
Working full time as a "Protocol Engineer" for a big company, taking care of pretty much everything related to AS/NAS on the network layer (2G, 3G, 4G).
I hate it, but it pays really well.
On my free time, revising ML/DL stuff from Udacity's nano (finished it last year) while studying for the VR nano and keeping my coding skills fresh (basic to advanced structures, coding strategies, best practices and stuff).
Love it, but usually I pay a heavy price to keep my mind in place.
Sometimes I just wish to give everythin up and travel the world with my 2 bucks and just try to get some rest. :v
To all of you who go through this kind of stuff, how are you holding up?1 -
I want to learn about the most important network protocols (HTTP 1/1.1/2, SSH, IMAP, SMTP, IMAP...) but reading the RFCs is extremely time consuming and probably not necessary for someone which doesn't need to implement these protocol.
Do you know more concise resources where I can learn more about the topic?9 -
I have been working on a long time, low progress project of mine that keeps on giving and giving.
Let's begin like two years ago where I dipped my toes into "more then gigabit" networking thanks to a Linus Techtips video about infiniband.
I had the dream of booting my Workstation from my NAS, a so called diskless setup.
Well, since I run FreeNAS on my Nas , a very nice Freebsd based Nas OS, everything's gonna be good.
In the beginning, there was no infiniband support.
Turns out, you don't need it, since the mellanox CX2 nics can do ETH too.
Yay.
Just took me a few weeks of anger.
So, to be able to boot something over the network, you need firmware that finds the bookable stuff and loads it.
That protocol and firmware is called PXE.
PXE needs a DHCP telling it what to do, and what is where and etc.
Freenas here I come! Installing dnsmasq on the actual freenas install turned out to be not that great of an idea because freenas thinks of itself as being an "appliance" that you don't fiddle with. So things work, until you update/ upgrade when everything will basically be wiped, except what you have done through the ui.
Ok. So I gona use a jail, a container like thing for that.
Everything is great, jail has internet, everything Installs fine, what could go wrong?
Dnsmasq can launch and work, but not as dhcp server. Some thing about permissions.
Turns out, jails have permission like things.
A few days of head scratching later, it has ALL the permissions.
Dnsmasq still can't work as DHCP server though, why you ask?
Because it needs a specific kernelmodule that isn't contained in the jail. Since jails are kind of like a docker container, they run on the same OS kernel, who does not have this module, I'd need to patch the freenas, which is an appliance, so fuck that.
Like a year later, freenas has finally added good VM support, so why not make a VM for the dhcpserver?
Well, about a year ago, I didn't know that the virtual Intel nic is a fucken unstable piece of garbage, crashing nearly any OS at some point.
So that was it for a while again.
Now to the last few weeks.
Finally dnsmasq is running in a freebsd VM with a good and working configuration which is rather simple, if those tutorial fuckers out there would explain shit instead of just telling you to copy, paste and replace X.
Now back to the PXE side.
I'm using iPXE because I have no clue how to boot anything over tftp so iSCSi it is, since that is what I can relate too.
The idea behind iscsi is to fake a SCSI disk over the network. Attached devices appear as if they are actually directly connected to the machine instead of over the network.
iPXE gets a lease from the server, can connect to it, everything is fucken great. Finally.
Except that if it "sanBoots" the iscsi drive, it can't find anything to boot.
Well fuck.
If I attach a Linux live USB over iscsi, it boots, finds grub, and crashes because the live iso isn't configured for network-boot.
But it boots.
So what's so different?
Well iPXE is booted in legacy mode, where as the content of the target is windows 10 in efi mode.
Ffff.
Ok. Can I get iPXE to boot in EFI mode?
Well yes, after like 3 days fiddling with it.
But it only finds the onboard Intel nic instead of the new Mellanox CX3 cards, and can't even connect to the target....
Sooo, I guess my options are as follows.
Either, get PXE efi to work on the network cards directly, its called flexboot and might be able to since I just found some firmware options for that.
Or give up on efi and install windows in legacy mode.
Which isn't that easy when it has to end up on a drive on my nas.