Assume I,m in a LAN, that uses a Router. If someone redirects my all data packets to his computer then there is no privacy. This is happening in real. when I run "arp -a" command, I can see his IP address and I couldn't remove it using command "arp -d ". Does anyone know a way to avoid this arp access? or any other suggestions?
Thank you.
Once a packet leaves your computer, there is really nothing you can do to choose where it goes or who captures it. It's best to always assume that anyone can capture and observe all of your traffic on the network. If that is not acceptable, you should use a protocol (e.g., SSL) that encrypts the communication.
Actually it is "ARP protocol Vulnerability" which is in the OSI model. As far as I know , this is under research & currently UNRESOLVED. iN lINUX U CAN AVOID THIS BY USING IPTABLES.
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I'm still a beginner in SDN and all that comes with it (openflow, mininet, opendaylight...) and so if I say a mistake, please excuse my ignorance.
So my request is about marking ip packets by openflow switches: I want to intercept packets coming to switches (by iptables that will send packets in a nfqueue queue) so that the switch can then mark them with its own information (identifier, distance from destination...) on the id field of an ip packet.... this information is then collected by the destination to reconstruct the path taken by the packet.
How can I enable a switch to mark packets like this? what commands should I execute? what language to implement the process? Where should I access it?
knowing that I have already implemented in C the marking process that works well in the traditional network (I tested it in a quagga router). can this code be useful to me for something in the mininet switches?
then if I don't use mininet, can OVS switch do the job? how?
Sorry, if I hadn't been more specific, but in anyway I'm here to answer any questions. I hope you can help me clear the way to get started.
Thank you.
I will recommend you to use Ryu controller (a python based SDN controller). Regarding Queuing, packet marking and MPLS, you can check the chapter 12 QoS from the Ryu Book. There are detailed examples there. I hope it will work for you.
if you manage your switches with OpenDaylight, then you don't want to use iptables.
you can use the openflowplugin to write flows to the switch to do all you want. I
think you can have a match-all kind of flow that will have the action you require
to "mark ip packets".
This may not be in the right location, so tell me and I'll move it.
I am a recent EE grad and I was hired to build a system that exists on a SoC with a simple 32-bit processor. The system basically monitors several external devices and performs some DSP on it, and then is supposed to send the results using a WiFi device (in my case I have the ESP8266 using UDP) to an email server for logging/notification.
I have been trying to find a library that I can use, but my uC can only program in C and I have it set up for UDP, and everything is in C++ using some other protocol, or something else completely.
I am great at DSP, decent at SoC's and uC's, but when it come to this email server communication thing I am at a loss.
I have successfully configured everything for the sensors, the datapath, the DSP, and connected the system to my WiFi via UDP, but I have yet to figure out how to send data to any servers.
Could someone help me understand how I should go about this?
I have looked into some simple SMTP commands such as HELO, MAIL, RCPT, DATA, etc. but I cannot understand how I actually should implement them in my code.
When I send out the WiFi data via UDP what type of data do I send and how do I format it? Do I need to send any other kind of flags? How should I expect the response? I also know the data has to be transformed into base 64 which is confusing me further.
I am also not super familiar with UDP to begin with, I have been using libraries that are part of the SoC's default library to connect to my WiFi.
I know these may either seem like obvious or stupid questions but it is were I no longer have any knowledge, and everything I find online doesn't make sense, or doesn't attempt to explain it, just gives a pre-made solution
I have found the RFC2821 but it doesn't get any clearer.
I know that's a lot but any help at all would be a lifesaver!
Since you are asking this question, I'm assuming that you are not booting and running an OS suitable for micro-controllers such as an embedded variant of Linux or such. If you were, you would simply be able to take advantage of possibly built in applications or other existing code.
But you don't mention having written an Ethernet stack, so are you using some other library or operating environment which might have some of the functionality needed for an implementation of SMTP?
If you don't and really do need to write your own SMTP client to run directly on the processor you are using, then you should be able to find plenty of examples of source code for this. A quick google search of How To Write an SMTP client showed a few articles with some example code. One article seems to be an exact hit, but you need to look at it further.
However, I would highly suggest just sitting down with a telnet client and connect to an SMTP server you are allowed to use and try the commands you need to just send a message. If you only need to send text, you don't need to get involved in MIME encoding or anything like that.
TL;DR available at the bottom
I've been trying to figure out a way to get two laptops (both running Ubuntu) to be able to pass basic messages back and forth without the need for them to be connected via a wireless network,either by an AP or ad-hoc. I want to reiterate here that ad-hoc networking is not what I'm looking for, I've seen many similar questions here with that as the answer.
I guess what I'm asking is: how do I achieve this? All I really need is for one computer to be able to send a packet, and then for another to pick it up via a packet sniffer of some kind.
Currently: I have both laptops in monitor mode (via a mon0 interface created from aircrack-ng's airmon-ng)so that they can sniff nearby traffic (with Wireshark, tcpdump,tcpcump.org's sample libpcap code, and opening a raw socket and just printing out all the packets. I tried each just because I thought one could be doing something differently/leaving something out). I also have a very basic program that consists of opening a raw socket to send crafted ethernet frames out to the air, but I can't get my two machines to see the other's packets. The sniffer running on each machine can only see the packets going out of that machine (in addition to nearby beacons/control traffic from wifi in the area).
Some things to note that might be important are:
-the packets I'm sending out appear in Wireshark (only on the sending machine) as malformed 802.11 packets (probably because I'm just filling them with junk data for now). I was under the impression that my other laptop would also see them as malformed packets, but it gets nothing
-the sockets I'm using are from a call to socket(PF_PACKET,SOCK_RAW,ETH_P_ALL). Raw sockets are something I just recently was aware of, so I could be misunderstanding how they work, but my impression is that I can craft a layer 2 packet by hand and ship out straight out to the wire/air.
If you're curious as to why I want to do something like this, it's part curiosity, part research for a project I'm working on. I want to streamline / automate the process of setting up an ad-hoc network, and what I'm trying to do here is for the laptops to do a small exchange to figure out the specifics of the adhoc network they are about to create and then make/join that network automatically, instead of either one person explicitly setting up the network OR having both people pre-decide the name, etc of the network and have both computers constantly trying to connect to that specific one.
I'm more interested if I'm going about this process in the right way rather than if my code works or not, if someone thinks me posting my (very basic, taken from another post on Stack Overflow) raw socket code will help, I can.
Edit: I am more than happy to post a complete set of code with instructions if I can get this working. I couldn't find much helpful info on this topic on the internet, and I'd love to put it up for future people trying to do the same thing.
TL;DR I want to send out a packet from one laptop and pick it up on another via a packent sniffer of some sort. No wifi network or ad-hoc network involved. Something akin to spoofing an AP's beacon frame (or similar) for the purpose of sending small amounts of data.
Edit 2:After some thought, perhaps what I'm looking for is some kind of raw 802.11 use? Having direct control of the wifi radio? Is such a thing possible?
I found out I was able to send packets out through my monitor mode interface as long as I had correct 802.11 with radiotap headers. I think the problem I was originally experiencing (not being able to sniff the packets) was because they were malformed and thus not actually getting sent out.
I was able to accomplish this by adapting the example code found here, courtesy of someone named Evan Jones, except I did not need to use an Atheros based card or Madwifi drivers, everything worked fine with the mon0 interface created with aircrack-ng.
I am certain that Apple Mac do this. Apple call it 'bonjour'. There may well be a proper IETF spec for it. This is an Article on Bonjour this is Wikipedia on an open component of bonjour which might help get you moving.
I am writing a udp chat application in c. I need to test if messages are received in an incorrect order. CAn anyone please tell me of a tool I can use to delay certain messages? also please tell me how to use it? thank you very much in advance! also I am using ubuntu x86_64 and OSX 10.6.4. A tool in either OS will work
When I created a syslog server I needed to see if it was catching the messages.
I used Wireshark from http://www.wireshark.org/ . This is a free tool that shows you all traffic passing your network cable. Even packages not intended for your computer.
Have fun...
If you need to verify this, you probably also don't want messages to disappear (or at least know if they do). UDP doesn't sound like what you want. Have a look at implementing this using TCP instead, you get this behaviour with the protocol.
is it possible to capture some packets in promiscuous mode (e.g. using winpcap) and than force OS (applications) to receive them as they were sent for our MAC?
My observation is following. We can:
capture all network traffic using
promiscuous mode (winpcap)
filter/modify the packets using
firewall-hook/filter-hook
send packets to the network with altered MAC
I am not sure if firewall-hook can access all the packets which are available thanks to promiscious mode. Isn't it on the lower layer? If it can't, the only solution would be to capture desired packets and then resend them to the network with altered MAC?
I am networking novice so please be easy on me :)
Any help is appreciated.
Thanks in advance.
You have your toes at the line of white hat/black hat hackers. I know that my company actively watches for promiscuous NICs, hunts down the owners and kills (fires) them. Maybe if you ask us what you're trying to do, we can offer some suggestions.
If you're trying to analyze your network, there is software and/or hardware solutions that will probably do a better job. If you're just trying to watch interesting text flow across your network, well ... maybe you're still in college.
First, yes if your interface operates in promiscuous mode then you will receive everything 'on the wire'. Which is already one difficulty, nowadays many (if not all) networks are switched, which means a piece of hardware exterior to your system will already do some filtering before packets arrive at your system, so you'll first need to trick a switch into transmitting those packets to your end (can be done by sending out dummy arps, by configuring the switch, or by bad intent ;-) ).
Then if these packets receive at your system, what do you plan to do with them ? There ethernet frames will carry ip packets, typically with a destination ip address, which is already something which will not be on your host (and if it is, this implies that you will have duplicate ip addresses on your network, causing problems as well.
So the main question is, what do you really really really want to do ?
Once you have recieved a packet, it has already been clean through the protocol stack. I don't think Windows gives you the access into the middle of Winsock that would be required to somehow stick it back in.
More importantly, this is a really dodgy think to be looking to do. Whatever it is you are looking to do, I can guarantee you there is some better way to do it.