shotgun prototype

README.md

@@ -2,6 +2,14 @@
 
 Realistic DNS traffic simulator with many independent clients
 
+## Current status
+
+- under development: active branches unstable, docker containers should work
+- prototype for processing inut PCAPs is functional, but slow and requires
+  python-dpkt from master
+- prototype for sending traffic is able to simulate UDP clients
+- dnsjit extensions are not merged upstream
+
 ## Overview
 
 The idea is to simulate many simultaneous clients with real behaviour, e.g.
@@ -14,8 +22,14 @@ of view.
 
 ### Dependencies
 
+#### pellet.py
+
 - python-dpkt (latest from git, commit 2c6aada35 or newer)
 
+#### shotgun.lua
+
+- dnsjit (with dnssim installed from https://github.com/tomaskrizek/dnsjit/tree/simulator )
+
 ### Input data
 
 To have a realistic simulation of clients, no synthetic queries are created.
@@ -44,13 +58,37 @@ time period.
 Simulating tens thousands of individual clients is challenging, especially with
 TCP. Plans are to support UDP, TCP and TLS.
 
+For ease of use, docker container with shotgun is available. Note that running
+``--privileged`` can improve its performance by a few percent, if you don't mind
+the security risk.
+
+```
+docker run registry.labs.nic.cz/knot/shotgun:20191002 --help
+```
+
+#### Shotgun
+
+The machine that will act as the sender of the traffic should have enough IPs
+and ports to avoid their exhaustion. This is especially important for TCP/TLS.
+
+Only IPv6 is supported right now. You can use the fd00::/8 range to create
+unique local addresses and assign multiple of them to a single interface.
+
+It's also a good idea to extend the port range. In my testing with linux
+kernel 5.3.1, it seemed once a half of this range is depleted, creating a new
+socket starts to take a significantly longer time, slowing the tool down. I'd
+recommend planing the expected port usage to utilize no more than half of the
+port range per IP.
+
+```
+sysctl -w net.ipv4.ip_local_port_range="1025 60999"
+```
+
 #### UDP
 
 - On the server, make sure the socket's receive buffer is sufficient.
   Otherwise, many packets can be lost, resulting in low response rate.
 
   ```
-  net.core.rmem_default=4096000
+  net.core.rmem_default=8192000
   ```
-
-TODO