if you need to connect an entire building over a directional radio link). That said, there are ways to implement layer-2 bridging with Wi-Fi (e.g. On Linux the same ip link … commands should work. Atheros usually supports this, while some Realtek cards might not).
#Python packet sender drivers#
Unlike Ethernet, though, the ability to do so depends on the specific wireless hardware and drivers (e.g.
#Python packet sender mac#
However, you can still set a different MAC address on the wireless interface, and use that new address for everything, starting with association/authentication to the AP. APs can do whatever they want – it's part of their job, after all, to send packets on behalf of wired devices.) (This is from the perspective of a station. Wi-Fi is a bit more restrictive – you cannot send individual packets with spoofed source, as APs keep track of all stations that are associated to it, and will (AFAIK) discard packets coming from any MAC address that's not in the "associated stations" list. Linux even has a "macvlan" feature to create virtual interfaces with different MACs on the same physical Ethernet card: # ip link add fred0 link eth0 type macvlan mode private # ip link set eth0 addr ab:cd:ef:ab:cd:ef On Linux, ip link would change the MAC address until next reboot: # ip link set eth0 down For the latter, use existing tools like libpcap, Scapy, or Nemesis. You can either change the MAC address of the network interface (telling the OS to use the new address for everything it transmits), or use "raw sockets" from an individual program to craft and send whatever you like, bypassing the TCP/IP stack.
#Python packet sender windows#
Linux, FreeBSD, Windows even have an option to create 'bridges' linking multiple physical Ethernet interfaces together, working exactly like a real Ethernet switch would (even with VLANs and RSTP). In fact, virtual machine systems (like VMware or Hyper-V) already use this to connect VMs to your real LAN – you might have multiple VMs attached to a single Ethernet card, and each VM will have its own MAC address independent from the host. A lower value raises average throughput by utilizing MTU capacity more efficiently.Over Ethernet – yes, the entire frame including its Ethernet header is sent by your operating system, and the OS decides what source MAC address to use.
If the number of packets overwhelms any receiver, try a lower value.To reduce average latency, try raising the value.Select an initial value based on capacity of the receiving CPUs to handle NIC interrupts. To begin, try a value within the range 50,000 to 150,000 packets per second.The general goal is to determine the highest value that does not overwhelm any receiving hardware.Use these guidelines as you empirically tune this parameter: When an application rapidly sends one small message per send call, then adjust the packet send limit to increase throughput efficiency.
However, if slow receivers report dataloss, then consider tuning the packet send limit (see the next item). For best results in most situations, set the packet send limit to zero.
When an inbound packet arrives, the cost of the NIC interrupt is independent of the size of the data in the packet. Hardware limits on the number of NIC I/O interrupts translate into limits on the receiver’s inbound message rate. However, even if the data send rate is low, a high packet send rate can still overwhelm a receiver. Limiting the packet send rate also limits the data send rate (bytes per second), because the data send rate varies with the packet rate and the data sizes of the packets. To prevent these scenarios, you can limit the rate at which sending programs transmit UDP packets to the network.Īdministrators can empirically tune the flow of data packets from sending programs by adjusting the packet send limit, which is a required property of UDP-based transports. With UDP-based transports such as multicast, fast sending programs can overwhelm slower receiving programs, which could result in retransmission-related latency, extra resource consumption of CPU cycles and network bandwidth, retransmission storms, or data loss.
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