packets

I tried a prerouting rule to redirect incoming packets to a internal virtual IP address. How can I log an incoming packet before it gets redirected? iptables -t nat -A PREROUTING -d 46.X.XX.XX -s 78.XX.XX.XX -p tcp --dport 80 --sport 1024: -j DNAT --to-destination 192.168.122.10:8080 The following rules didn't work. iptables -t nat -A PREROUTING -d 0/0 -s 0/0 -p tcp -j LOG --log-level 4 iptables -t nat -I PREROUTING -d 0/0 -s 0/0 -p tcp -j LOG --log-level 4 You need the logging rule to be at the very beginning of your rules. # iptables -I INPUT 1 -m limit --limit 5/m -j LOG --log-prefix=

I need to inject some L2 packets(customized) to an specific interface as incoming packets in Linux to test some applications running on it. Is there any libraries(python preferred)/examples that can help? I was skimming through the Scrapy library, but then it looks like it can only inject packets to the network as outgoing packets? If you have the native linux bridge module available then you can use it in this way. Create a bridge brctl addbr <brname> Now create a virtual eth pair (default names veth0 , veth1 ). veths are connected L2 devices ip link add type veth ifconfig veth0 up ifconfig

Is it a well known fact that UDP (User Datagram Protocol) is not secure, because the order of the packets sent with it may not be delivered in order, even at all. However if an UDP packet is delivered. Are the information in that packet in practical sense (99.99% and above), guaranteed to be correct? Is a UDP packet quaranteed to be complete (not corrupted) if delivered, in practical sense (99.99% and above)? Thanks in advance! No for two reasons: UDP checksums are not mandatory (with IPv4). So corrupted packets can be delivered to applications. Internet checksums can clash much more

I want to use a RAW Socket in Visual C++. I saw a function on Linux which is int out = socket(AF_INET, SOCK_RAW, htons(ETH_P_ALL)); Using this code in linux we can do that, but how to use RAW SOCKET on Windows Platform because when I use this in Visual C++ I am getting Error. Thanks in Advance. EDIT int out1 = socket(AF_INET, SOCK_RAW, IPPROTO_SCTP); for (; ;) { int bytesIn = recvfrom(out1, buf, 2000, 0, (sockaddr*)&server, &serverLength); if (bytesIn == SOCKET_ERROR) { cout << "Error Receving from Server" << WSAGetLastError() << endl; } else { cout << "MESSAGE RECV from Server " << " : " <<

I've written a number of networking systems and have a good idea of how networking works. However I always end up having a packet receive function which is a giant switch statement. This is beginning to get to me. I'd far rather a nice elegant object-oriented way to handle receiving packets but every time I try to come up with a good solution I always end up coming up short. For example lets say you have a network server. It is simply waiting there for responses. A packet comes in and the server needs to validate the packet and then it needs to decide how to handle it. At the moment I have