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| -rw-r--r-- | man/trafgen.8 | 164 |
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diff --git a/man/trafgen.8 b/man/trafgen.8 index 80c1359..a919ed8 100644 --- a/man/trafgen.8 +++ b/man/trafgen.8 @@ -162,10 +162,166 @@ Show versioning information. Show user help. .SH SYNTAX -TODO - -.SH SOURCE EXAMPLES -TODO +trafgen's packet configuration syntax is fairly simple. The very basic things +one need to know is that a configuration file is a simple plain text file +where packets are defined. It can contain one or more packets. Packet are +enclosed by opening '{' and closing '}' braces, for example: + + { /* packet 1 content goes here ... */ } + { /* packet 2 content goes here ... */ } + +When trafgen is started using multiple CPUs (default), then each of those packets +will be scheduled for transmission on all CPUs on default. However, it is possible +to tell trafgen to schedule a packet only on a particular CPU: + + cpu(1): { /* packet 1 content goes here ... */ } + cpu(2-3): { /* packet 2 content goes here ... */ } + +Thus, in case we have a 4 core machine with CPU0-CPU3, packet 1 will be scheduled +only on CPU1, packet 2 on CPU2 and CPU3. When using trafgen with --num option, +then these constraints will still be valid and the packet is fairly distributed +among those CPUs. + +Packet content is delimited either by a comma or whitespace, or both: + + { 0xca, 0xfe, 0xba 0xbe } + +Packet content can be of the following: + + hex bytes: 0xca + decimal: 42 + binary: 0b11110000 + octal: 011 + character: 'a' + string: "hello world" + shellcode: "\\x31\\xdb\\x8d\\x43\\x17\\x99\\xcd\\x80\\x31\\xc9" + +Thus, a quite useless packet packet configuration might look like this (one can +verify this when running this with trafgen in combination with -V): + + { 0xca, 42, 0b11110000, 011, 'a', "hello world", + "\\x31\\xdb\\x8d\\x43\\x17\\x99\\xcd\\x80\\x31\\xc9" } + +There are a couple of helper functions in trafgen's language to make life easier +to write configurations: + +i) Fill with garbage functions: + + byte fill function: fill(<content>, <times>): fill(0xca, 128) + compile-time random: rnd(<times>): rnd(128), rnd() + runtime random numbers: drnd(<times>): drnd(128), drnd() + counter: TODO + +ii) Checksum helper functions (packet offsets start with 0): + + IP/ICMP checksum: csumip/csumicmp(<off-from>, <off-to>) + UDP checksum: csumudp(<off-iphdr>, <off-udpdr>) + TCP checksum: csumtcp(<off-iphdr>, <off-tcphdr>) + +iii) Multibyte functions, compile-time expression evaluation: + + const8(<content>), c8(<content>), const16(<content>), c16(<content>), + const32(<content>), c32(<content>), const64(<content>), c64(<content>) + + These functions write their result in network byte order into the packet +configuration, e.g. const16(0xaa) will result in ``00 aa''. Within c*() +functions, it is possible to do some arithmetics: -,+,*,/,%,&,|,<<,>>,^ +E.g. const16((((1<<8)+0x32)|0b110)*2) will be evaluated to ``02 6c''. + +Furthermore, there are two types of comments in trafgen configuration files: + + 1. Multi-line C-style comments: /* put comment here */ + 2. Single-line Shell-style comments: # put comment here + +Next to all of this, a configuration can be passed through the C preprocessor +before the trafgen compiler gets to see it with option --cpp. To give you a +taste of a more advanced example, run ``trafgen -e'', fields are commented: + + /* Note: dynamic elements make trafgen slower! */ + #include <stddef.h> + + { + /* MAC Destination */ + fill(0xff, ETH_ALEN), + /* MAC Source */ + 0x00, 0x02, 0xb3, drnd(3), + /* IPv4 Protocol */ + c16(ETH_P_IP), + /* IPv4 Version, IHL, TOS */ + 0b01000101, 0, + /* IPv4 Total Len */ + c16(58), + /* IPv4 Ident */ + drnd(2), + /* IPv4 Flags, Frag Off */ + 0b01000000, 0, + /* IPv4 TTL */ + 64, + /* Proto TCP */ + 0x06, + /* IPv4 Checksum (IP header from, to) */ + csumip(14, 33), + /* Source IP */ + drnd(4), + /* Dest IP */ + drnd(4), + /* TCP Source Port */ + drnd(2), + /* TCP Dest Port */ + c16(80), + /* TCP Sequence Number */ + drnd(4), + /* TCP Ackn. Number */ + c32(0), + /* TCP Header length + TCP SYN/ECN Flag */ + c16((8 << 12) | TCP_FLAG_SYN | TCP_FLAG_ECE) + /* Window Size */ + c16(16), + /* TCP Checksum (offset IP, offset TCP) */ + csumtcp(14, 34), + /* TCP Options */ + 0x00, 0x00, 0x01, 0x01, 0x08, 0x0a, 0x06, + 0x91, 0x68, 0x7d, 0x06, 0x91, 0x68, 0x6f, + /* Data blob */ + "gotcha!", + } + +Another real-world example by Jesper Dangaard Brouer [1]: + + { + # --- ethernet header --- + 0x00, 0x1b, 0x21, 0x3c, 0x9d, 0xf8, # mac destination + 0x90, 0xe2, 0xba, 0x0a, 0x56, 0xb4, # mac source + const16(0x0800), # protocol + # --- ip header --- + # ipv4 version (4-bit) + ihl (4-bit), tos + 0b01000101, 0, + # ipv4 total len + const16(40), + # id (note: runtime dynamic random) + drnd(2), + # ipv4 3-bit flags + 13-bit fragment offset + # 001 = more fragments + 0b00100000, 0, + 64, # ttl + 17, # proto udp + # dynamic ip checksum (note: offsets are zero indexed) + csumip(14, 33), + 192, 168, 51, 1, # source ip + 192, 168, 51, 2, # dest ip + # --- udp header --- + # as this is a fragment the below stuff does not matter too much + const16(48054), # src port + const16(43514), # dst port + const16(20), # udp length + # udp checksum can be dyn calc via csumudp(offset ip, offset tcp) + # which is csumudp(14, 34), but for udp its allowed to be zero + const16(0), + # payload + 'A', fill(0x41, 11), + } + + [1] http://thread.gmane.org/gmane.linux.network/257155 .SH USAGE EXAMPLE TODO |