I'm studying tcp/ip networks and therefore also studying the history of the internet, and a question arose about the ARPANET and how it works, which I couldn't find an answer to. can you help me?
The doubt is that before the implantation of tcp/ip and after the implantation of imp, how did these ARPANET machines know where one was the other and how this connection happened?
I hope you understood :)
Thanks!
I tried to relate the protocols of the time with the current ones but it didn't work.
Related
Is there any good book about networks and network protocols? One question I currently have is: How does the operating system determine the IP address of the router in a LAN?
I want to understand those basics. I know that I can look up most of the common protocols by searching for their respective RFC, but I don't even know which protocols are used for which purpose.
The operating system knows the ip address of the first router (default gateway), because someone told it - either manually when configuring the TCP/IP settings or dynamically via DHCP, BOOTP or similar.
There are plenty of good book suggestions in the closed question "What are good books on computer networks"
http://www.pearsonhighered.com/kurose-ross/
http://books.google.co.in/books/about/Computer_Networks.html?id=Pd-z64SJRBAC
Both are good books. Enjoy !!
First, I need to know this in kernel space, so please take this into consideration.
No, I cannot use the IP address of the other device and ARP it(too long to explain why here) but I simply cannot use ARP, ARP won't work for the project I am working on.
Is there a function/utility I can use to know the MAC address of the other end in a connection attached to a given net_device I already have regardless of the IPs?
Thanks in advance, and if my question is not clear or makes no sense, leave a comment and I'll make sure to edit the question to explain/fill in the gaps
The standard protocol for "I need to speak to my neighbor" kind of problems is LLDP. At the moment, this is usually implemented via OpenLLDP (user-space) on Linux systems. However, there appears to be some kernel-space patches on the way that might help you:
Supposing you have the possibility to enable LLDP on the other end, you should be able to use it to discover that device.
I have an old school foxpro web app that I am trying to help limp along while I rewrite the system. Every day, multiple times, I get this following error message: The specified network name is no longer available.
Does anyone have any suggestions how to troubleshoot this? Perhaps, prove to my IT guys that there really is a network issue. I have theories, but I have no idea how to prove anything, it always comes back to foxpro sucks rewrite it now.
I'll take any help, tools, and will answer any questions that may clarify this for you.
thanks
We have a very large multi-user VFP application on hundreds of sites. Occasionally you get this sort of problem. It is almost always down to environmental issues.
Had one just recently where a client had two machines continually crashing out of the VFP application. Network IT guys swearing up and down that it's not their problem. But what's this in the System Log of both machines? Why, it's the Broadcom NIC reporting a network link loss detected at the same times the application crashed.
Check if the client and server NICs in your situation can report this.
You could consider writing a small program that pings the network resource periodically. You might just look for a file and if the network is failing and the program cannot find the file email the folks in charge of the network and yourself. This would be an independent app, and best if not written in FoxPro so you can independently prove it is not the application or the language/tool it was written in.
I have seen this when networks have bad wiring, a bad port on the switch/hub, a failing NIC in the mix, and sometimes when the network is just flooded with requests from workstations.
You also did not mention if this was a wireless connection. I am hoping not, but I have seen wireless (especially slower wireless) hubs fail with respect to the network overload and slow and unreliable performance. Especially compared to a wired network.
Rick Schummer
In addition to the comments about IP address, is the setting on the network controller to be energy efficient? and thus turn itself off when not actively in use.
So I want to learn all about networks. Well below the socket, down to raw sockets and stuff. And I want to understand hubs, routers, access points, etc. For example, I'd like to be able to write my own software to do this kind of stuff.* Is there a great source for this kind of information?
I know that I'm asking a LOT here, and that to fully explain it all requires from high level down to low level. I guess I'm looking for a source similar in scope and depth to Applied Cryptography, but about networks.
Thanks to anyone who can help to point me (and others like me?) in the right direction.
* Yes, I realize using any of my hand-crafted network stack code would be a huge security issue, and am only looking to do it to learn :)
Similar Question: here. However I'm looking for more than just 'what's below TCP/UDP sockets?'.
Edited for Clarification: The depth I'm talking about is above the driver level. So assuming that the bits can make it to and from the other end of the wire, what next?
I learned IP networking from TCP/IP Illustrated. Highly recommended.
This may not help you learn it, but a packet sniffer like Wireshark will give you some insight into what the data looks like at a pretty low-level protocol (TCP/IP).
As you have obviously recognised, the universe does not start and end with the IP Protocol. Take a look at the OSI 7 Layer Model where IP is a Layer 3 (Network) protocol. Common IP Routers will operate at this level, but there is more complexity you probably should understand in the Data Link and Physical layers before you start coding your own network stacks.
Start with the fundamentals of data communications in all its myriad forms and work your way up the stack until you get to where you need to stop. Data Communications, Computer Networking and Open Systems is a good foundation text, and then look for more detail on each area you need to focus on. Previous answers include good links for IP and TCP/IP, and as mentioned Wireshark will let you look down through some of the layers
CISCO CCNA materials contain a great network fundamentals, but does not affect programming aspect. I'm not sure that there is an official free link, but you can try to find them.
You should equip yourself with a c compiler and the necessary libs and headers for your OS and play around. You may want to read for example:
http://snap.nlc.dcccd.edu/learn/fuller3/chap13/chap13.html
I had some more links in my delicious account, but they all went down the digital drain ;-)
Have you any embedded programming experience ? If so I recommend you buy one of these development boards. They are cheap and allow you work on every part of the networking stack plus all the software tools required are free.
Note that getting going on it isn't easy and I ended up reading the CS8900 IC datasheet to learn how to make it communicate with the ARM7 based processor. But if you enjoy that sort of thing (as I do) then they are great fun.
Hmmm ... have you looked into Computer Networks by Tanenbaum ?
The TCP/IP Guide
I have found the networking chapter in "understanding the linux kernel" and "understanding linux network internals" from oreilly to be very helpful.
The TCP/IP stack is a very good start but there is a lot more and a good understanding of how ethernet works and how ethernet != IP != the-interweb will go a long way.
books on network security often do a decent if not goos job explaining how networks work in a concise context.
what really did the trick for me was taking a job implementing NAT :)
This course worked for me: COS 461 at Princeton. Note that it assumes system-level programming experience with C.
Pretty much all the readings and lectures are available online under "Syllabus". And you can try the assignments too (unfortunately, you won't have access to the Virtual Network System).
Check this.. it is a good collection of information:
http://www.tcpipguide.com/free/t_toc.htm
This is more a thought experiment than anything.
I'm wondering what it would take to detect everything I legally can about the laptops in a hotspot. My first thought was to grab every MAC address I can and extract the maker from the first 24bit.
The question is would this be illegal and what else could I legally scavenge, preferably passively?
P.S. This constitutes a pattern-recognition problem so it IS programming... I think.
nmap can do a reasonable job of guessing the operating system by the way the target system responds to various probes
For the brain dead answer: Quit typing and look around for a few minutes :-D
I guess the obvious one would be to sniff the user-agent out of their HTTP requests.
IIRC there are ways to detect what TCP/IP stack is being used by sniffing choices in port usage and sequence numbers.
Why does it matter, 90% of them will be apples ;-)
The people wearing black turtle necks will be using Macs, the rest will be using PC's and Windows (except for that one guy with long pony tail who is using Linux).
Packet sniffing is illegal without the network owners consent. At least that's the generally followed precedent. There has been very few tests of this in court. But your idea of how to do it, using the mac addresses, would work well. Wireshark is a good packet sniffer if you're looking.
GFI Languard gives a lot of info like this. Check it out.