Oh networking is easy first you go to linkedin Then… You run
The problem with networking is debugging it. The worst is debugging iptables and nftables. Figuring out which chain they are going to is a massive hassle. How come we don’t have any graphical tools whatsoever for this work?
There’s nothing to debug, it’s fucking DNS again, you know it is.
Packet Tracer?
That’s a very generic name. Do you have a link?
Sure thing, here you go:
As for iptables, doesn’t
-jtell you where the packets are going? Or do you mean what their destination addresses and ports are? For that, on Linux, I usessorlsof. I have never used it myself, but doesn’tufwhave some GUI?Reading the iptables dump is not for beginners. Far from it. A packet can go through all tables and chains or none. And allowing a packet in one chain then begs the questions which is the next table or chain. There are maybe 100 flags and nobody can memorise them all.
Ufw just allows adding rules,
ssdoesn’t trace packages as they go through the firewall, it can show you open ports and established connections, but it can show you which tables and chains a packet went through.lsofis even more rudimentary thanssand literally means “list open files”. Since everything is a file in linux, that’s a lot of files. Again, no tracing.Somebody will say “just
tcpdump”. Again, no that doesn’t trace which tables and chains a packet goes through. The entire firewall is a blackbox totcpdump. At least to my knowledge. All it sees is which packets arrived and which were sent on the selected interfaces, and whether they was successful or not.Nothing I know of traces a packet through the firewall and presents in a TUI nor GUI. I know that it’s possible to make copies of packets and send then to custom chains that can log the chain and packet it came from. There might even be a way of generating a trace by adding a rule to a chain, which means adding it to every chain, but I’m not sure I’ve seen something do that.
I digress. The documentation on iptables alone is an arduous read at best and requires dedication to get through and to understand. With that said, while you “cannot” (loosely said) follow any one singular packet from an iptables listing, using tcpdump will at least let you know wherefrom
itconnections originate and where they are terminating. Again, it is a hard read, not very beginner friendly, but I think it is also enough for the majority of threat models.Question: does the person that feels that reading and understand iptables listings and tcpdumps really need to know - through an easy to read/understand UI - what chains and tables any one specific packet has traversed? What scenario/threat model/situation would that be? I’m all for discussing and widening my point of view, so don’t hold back! 😊
Regarding your question, I’ve had trouble multiple times with docker (and other software) that required trying to find out just where a packet was getting stuck. The worst thing is when you open a port in the container to
0.0.0.0, send a request to it (HTTP, telnet, or otherwise) from the host via the container’s IP and the packet doesn’t arrive. Then you have to run through the gamut of:- are the interfaces up?
- is it the IP address that’s wrong?
- is the the port wrong?
- is the network mask correct?
- is the gateway IP correct?
- is the firewall somehow interfering?
There might be other things I’m missing, but once I get to the firewall stage, most of the time I just give up, put the service into a VM and try accessing it from there - if I really really care. Otherwise, I drop it and move on.
I did just find this Network address translation part 1 – packet tracing which allows tracing a packet through the firewall via
xtables-monitor. It’s in my notes now, so if I run into the problem again, I might have a place to start next time.But still, that’s just on my machine. Once things happen on the network and there are routers and other things involved, it’s very difficult for me to debug.
And my boss shattering all with mean comments. Not letting me explain my code but still tearing it all down, removing all security features like checking for directory existing, connection is open aso. and then saying im not qualified for the job! Good thing i got already laid off. Bad that i’ll still have to spend 3 months at this company
I’m so sorry about your job. :(
Do you mean that you were trying to write network conscious/safe code and your boss disagreed and laid you off for that reason?
No. This whole laying off story is bigger and longer Shortly said. Last year i did a project, alone, for a customer. I didn’t know that the version i gave him for review, was supposed to be the finished polished version. For me it was the rough work that he could have a look at, if the UI and functions roughly are as he expected them and whether he wants other changes. That brought the stone rolling.
Then the best friend of the only senior dev in this small company got into the position of team lead. There he constantly changed things up but i thought yeah what ever i write the texts differently. That was in december 2025. But the big issues then came in january and stronger in february. He bickered at how i named my variables, saying they werent accurate, leaving classes empty (just like the structure he build up was and i wanted to emulate it because i thought ‘well it got to have a reason why he did it that way’). For example the variable for a list for a table of employee time entries i called “employeesheet”. He marked it as completely wrong and that this isnt appropriate, giving as example that one of the translation of the word into german is “time note” and i should rather call it just “employeecollection”. I argued, that it does fit because sheet also can be used for a listing and this not being a collection could lead to confusion with wrongful expectations and this is only being a list to be displayed and printed. And asked for better clarification why he thinks that would be a better name. I never got that. Note that all other classes and lists were called “sheet” and not “collection” He also was constantly passiv aggressiv and i cant even recall all of it because its some time ago and lot has happened since then. During a “meeting” to clarify things. He got loud, mad and angry that the bosses didnt read the emails he send them complaining about me. This person had a history and i wasnt the first to be feeling his power tripp. Another collegue felt it at the same time and one even before it. We went to the bosses. This was all due to unclear communication. I even offered to write them a manial on how to phrase things so i understand it better. Got told it was not neccessary. I did it anyways after senior developer asked in an email exchange between me and the ass-leader
Then i was tasked to do a version 2.0 for that customer project. Alone. As the project began i was on the verge of ending up on the street and had to juggle housing search, my grandma (and mother figure) being diagnosed with end stage Thyroid cancer and my dad suddenly landing in hospital due to a huge cepsis. Due to all that stress i oversaw something major for the project. That i then ofc admitted to be my fault and worked hard to fix it all. Then i noticed (after having done this fix just in time) that without telling me this project got given to the senior developer instead.
What a motivation booster. At the time i also got told (end of june) that i’ll be laid off due to the financial situation. But in the case for the states approval (im 50% disabled meaning they have to get the states approval first) they stated “lack of skills for the position” as reason. In my statement i wrote how it all went down and that it was not due to lack of skill but due to stress in private that i oversaw that thing for the project.
Then the last few weeks i got tasked to programm something for a technologie which hasnt been in use since the 90s! And therefor ofc barely any documentation. I programmed it all regardless to the best of my abilities, having never interacted with Paradox (.px) database files or Oracle OR Borland Software before. Did it all dynamic, as i was taught in traite school, how i was always told to do things, even here). This still somehow was wrong lol. The safety things were: check that the repository exists before calling it. If not exists create it. Before trying to send a SQL Query to the Database, check that the connection is established and open.
Both i got told (along with gas lighting that apperently the call i had with my boss last friday according to him didnt happen) were unnecessary because “the folder will always be there”. I told him “nobody can gurantie that!”. He told me to shut up. I did for the rest of the call. He used the word “clone files” not “copy files” which in my book are 2 different things. And then got upset that i didnt copy the files but created new once from the templates. He treated me litterly like i never programmed. Didnt give me a few minutes to find the connections and how i arranged the methods, in the code i didnt touch in a week. It’s all so frustrating.
And yes they were aware from before they hired me that i have adhd and autism
No. This whole laying off story is bigger and longer Shortly said. Last year i did a project, alone, for a customer. I didn’t know that the version i gave him for review, was supposed to be the finished polished version. For me it was the rough work that he could have a look at, if the UI and functions roughly are as he expected them and whether he wants other changes. That brought the stone rolling.
Then the best friend of the only senior dev in this small company got into the position of team lead. There he constantly changed things up but i thought yeah what ever i write the texts differently. That was in december 2025. But the big issues then came in january and stronger in february. He bickered at how i named my variables, saying they werent accurate, leaving classes empty (just like the structure he build up was and i wanted to emulate it because i thought ‘well it got to have a reason why he did it that way’). For example the variable for a list for a table of employee time entries i called “employeesheet”. He marked it as completely wrong and that this isnt appropriate, giving as example that one of the translation of the word into german is “time note” and i should rather call it just “employeecollection”. I argued, that it does fit because sheet also can be used for a listing and this not being a collection could lead to confusion with wrongful expectations and this is only being a list to be displayed and printed. And asked for better clarification why he thinks that would be a better name. I never got that. Note that all other classes and lists were called “sheet” and not “collection” He also was constantly passiv aggressiv and i cant even recall all of it because its some time ago and lot has happened since then. During a “meeting” to clarify things. He got loud, mad and angry that the bosses didnt read the emails he send them complaining about me. This person had a history and i wasnt the first to be feeling his power tripp. Another collegue felt it at the same time and one even before it. We went to the bosses. This was all due to unclear communication. I even offered to write them a manial on how to phrase things so i understand it better. Got told it was not neccessary. I did it anyways after senior developer asked in an email exchange between me and the ass-leader
Then i was tasked to do a version 2.0 for that customer project. Alone. As the project began i was on the verge of ending up on the street and had to juggle housing search, my grandma (and mother figure) being diagnosed with end stage Thyroid cancer and my dad suddenly landing in hospital due to a huge cepsis. Due to all that stress i oversaw something major for the project. That i then ofc admitted to be my fault and worked hard to fix it all. Then i noticed (after having done this fix just in time) that without telling me this project got given to the senior developer instead.
What a motivation booster. At the time i also got told (end of june) that i’ll be laid off due to the financial situation. But in the case for the states approval (im 50% disabled meaning they have to get the states approval first) they stated “lack of skills for the position” as reason. In my statement i wrote how it all went down and that it was not due to lack of skill but due to stress in private that i oversaw that thing for the project.
Then the last few weeks i got tasked to programm something for a technologie which hasnt been in use since the 90s! And therefor ofc barely any documentation. I programmed it all regardless to the best of my abilities, having never interacted with Paradox (.px) database files or Oracle OR Borland Software before. Did it all dynamic, as i was taught in traite school, how i was always told to do things, even here). This still somehow was wrong lol. The safety things were: check that the repository exists before calling it. If not exists create it. Before trying to send a SQL Query to the Database, check that the connection is established and open.
Both i got told (along with gas lighting that apperently the call i had with my boss last friday according to him didnt happen) were unnecessary because “the folder will always be there”. I told him “nobody can gurantie that!”. He told me to shut up. I did for the rest of the call. He used the word “clone files” not “copy files” which in my book are 2 different things. And then got upset that i didnt copy the files but created new once from the templates. He treated me litterly like i never programmed. Didnt give me a few minutes to find the connections and how i arranged the methods, in the code i didnt touch in a week. It’s all so frustrating.
And yes they were aware from before they hired me that i have adhd and autism
That’s awful. I hope you’ll find somewhere better for you. Good luck!
In one college class we had to reimplement TCP in our own code on top of real UDP sockets. That was a fun class.
Why use UDP sockets when you can use raw Linux sockets with no encapsulation at all?
Fun, sarcasm?
I had a class where we did a similar thing, except it was re-inmplementing basic forms of internet and transport protocols on top of the link layer
And it was a really really fun class imo, no sarcasm
Same!
If it helps, I’m from the other side of networking and infra. You could swap the labels and make the meme accurate for me.
In the mid 1980s I learn the BASIC programming command GOTO and fell in love for a lifetime. If you look any anything I used to write in Ruby script or today in Python you’ll see my love affair with “if” “elfi” and “else” continues. My universe is nested “if” statements all the way down.
As a network engineer myself… python if/elif, and nested for loops are all you need
/s
Please avoid nested if statements. Instead use early returns when possible.
This seems geared more towards programming languages like C++, whereas in scripting such as BASH it seems to me like it absolutely would get to be a mess to have so many functions, particularly those called only once (either total for the execution of the entire program or within the context of being inside another function, so once per function).
I am curious now what would Linus Torvalds say about that?
Early returns seems good, but personally I find code more confusing when things get arbitrarily separated out into functions, because to read it you have to keep scrolling back and forth between different parts of the page and either remembering where the other part is or typing a lot with ctrl-f, there’s more variables to hold results, and if the section of code to be separated into a function is picked just because of nesting depth reasons then it’s likely the function name isn’t going to describe what it does very clearly, leading to more scrolling and more having to keep track of things in your head.
I’ve had this too. It was cured by being forced to work with Java and enhance a PHP-framework. Dear god, the php-framework.
But it literally increased my mental “stack size”. My shell and python scripts also got better.Ah, and also keep the “do one thing and do it good” tenet also to functions.
Getting good at reading bad code does seem like a worthwhile skill
A good IDE makes it unnecessary to scroll back and forth like that, though.
How? I’m using vscodium. There are right click menus that bring you to function definitions and uses, but that isn’t necessarily faster than scrolling around and is still way more friction and more stuff you can’t see to hold in your short term memory.
IDEs also have collapse/expand features which make nested or longer functions easier to navigate.
In a decent IDE you can CTRL+click (or similar) on a function name to go to its definition. This is absolutely faster than scrolling, especially if you’ve got more than a couple dozen lines in the current file.
When splitting functionality into smaller functions you would ideally not have to keep implementation details of other functions in short term memory.
You only need to understand/remember the contents of the current function. Does it do what the name suggests? Cool, you’re done checking it.Of course, the “2 hard problems in computer science” meme exists for a reason - it’s not always straight forward to come up with good names. But in my experience, even when coming up with a fitting name is difficult, reducing nesting usually helps a lot with comprehension, mainly because it reduces scope and thereby the amount of information you need to hold in your head.
The larger a function gets, the harder it is to check that it does what it’s supposed to.There is of course a balance to strike - trying to force every single function to be at most 3 lines is likely to make the code more difficult to understand and is, in my eyes, almost pathological. But a function that covers more than a screen is the other extreme that should be avoided when practical.
CTRL+click
Oh hey it works, thanks.
If you like
ifstatements, you’ll love the pythoncasestatements for pattern matchingOhhh nice! I could see replacing dozens of nested
ifstatements with dozens of nestedcasestatements!
Also don’t nest case statements. Please.
I remember one of the hardest transitions for me from scripting in Ruby to Python was the whitespace indent was larger by default in Python. With Python, I ran out of monitor width and would have to be constantly scrolling right and left when visually parsing the code because the nested loops were so deep.
Yes, but also, it makes for twistsd code.
It was fashionable at a time to avoid ifs and other imperative structures, but I tend to like them. Functional is nice and all but I like my code to be smart in the way it works, not in the way it’s written. Nested ifs are readable, collapsible, and easy to make sense of at a glance, there’s often nothing wrong with using them.
Same here! I can put together a half-descent network in just a few hours, but even programming simple stuff on microcontrollers is a major endeavor. And the documentation is usually terrible or nonexistent. And the tutorials are usually barely able to cover basic questions. At least in the space of networking, there’s enough context clues in the UI that I can piece together the solution I need.
My universe is nested “if” statements all the way down
Also known as AI 🤣
I may actually be the other way around. I’m probably better at networking than programming? Not sure, I love them both but do neither professionally.
I was like this 5 years ago. Networking a lot is still effort for me, but it is just another learnable skill, and it has lots of benefits (depending on your aims, I guess)
Edit: hah, just realised this is about connecting computers, not about talking to people…
Same diff
Only computer thing I still needed to call dad about as an adult.
Only wizards can configure iptables for ipv4 and ipv6 port forwarding. Only wizards.
What about nftables?
Extraterrestrials
Opposite for me lol
tcpdump looks scary but is super neat and helpful, learn it if you haven’t ;)
ack
Still doesn’t help with things like understanding routing and subnet masks and frame sizes and jfc how does any of this work
Of course not, but I’ve found that seeing the protocols in action and looking at real headers can be very helpful in making them click. Understanding DHCP or ARP or mDNS or BGP or whatever is much easier by inspecting a pcap than it is by reading RFCs
As someone who understands the concept of network but has never professionally entered the field, i assume this just dumps a TCP packet to be inspected, correct?
The tcpdumps I’ve worked with can also dump UDP, ICMP, and even ARP.
Tcpdump can also capture USB traffic!
Yes, but before I used it I assumed that its scope was pretty much limited to what you just mentioned. Instead it can operate on most protocols both above and below layer 4, and it is incredibly useful as a traffic capture tool to produce a
.pcapon a remote headless machine which you can then load into Wireshark. The “dump” part is the interesting one, not the “tcp” ;)Yes. Also learn about certs if you need to deal with encryption https etc.
Thank you for the affirmation, I got reverse proxies and certificates relatively down, however I am struggling to understand headers and their purposes, I know Mozilla has great documentation regarding headers but lately I’ve gotten lazy, haha.
HTTP headers or headers in general? For the former I suggest Burp Suite to inspect and manipulate headers to see how things change, for the latter tcpdump/wireshark, to supplement your theory reading :)
Thanks! I started with Wireshark, settled on tcpdump for a while and now I’m too busy learning electrical engineering to give any fucks at all. 🤣 Nah but seriously, tcpdump gave me lots of insight! :)
Electrical engineering is just layer 1 on the OSI model.
My confidence in disk management and partition tables is made of horse hair, single strand.
That’s why I decided to build my first online multi-player game as an offline single-player game, and just figure out how to add the networking stuff when everything else is done- an architectural choice I definitely won’t come to regret later…
I’ve enabled all the relevant permissions. I’ve disabled firewall protection. I’ve enabled file sharing on both sides. I’ve checked for connectivity to the other machine from the command line…
Why is my shared folder still not accessible!??!
I’ve been trying to remotely connect to a relational database of medical data. I’ve been smashing my head against a keyboard for days trying to get my fucking code to work. I can’t even connect to their db on their Jupyter Spark cluster
Ooh medical data, bet there is some security involved that “gets in the way”.
It absolutely is. I’m dealing with genetic data, so I’m on their high security tier. Right now, the signs point to some poorly documented environment variables that aren’t sourced on startup for some reason
