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dnstress

General description

dnstress is a tool that provides performance stress tests for defined DNS servers.

Features

Commandline parameters

Parameter	Description
`-c, --config=CONFIG`	File with a dnstress configuration (described in the section below)
`-l, --ld-lvl=LD-LVL`	Load level of stressing. The value has to be from 1 to 10. You can not use it with `--rps` option
`-r, --rps=RPS`	Number of requests per second. You can not use it with `--ld-lvl` option
`-m, --mode=MODE`	Traffic generation mode (udp-valid by default). Possible values are: <ul><li>udp-valid: UDP valid packets</li><li>tcp-valid: TCP valid packets</li><li>udp-nonvalid: UDP non-valid (to be blocked) packets</li><li>tcp-nonvalid: TCP non-valid (to be blocked) packets</li><li>shuffle: random packets generating</li></ul>
`-o, --output=OUTFILE`	Output to OUTFILE instead of to standard output. This option isn't availbale for now
`-v, --verbose`	Produce verbose output. This option isn't availbale for now
`-V, --version`	Print program version

Configuration file

First of all, dnstress uses a configuration file to setup some of internal structures. The default path is ./dnstress.json (it will be changed in the future). The example of a configuration file is shown below:

{
    "addrs": [ "127.0.0.2", "127.0.0.3", "[2a0d:b600:166:ff00:e2d5:5eff:fe3a:a880]:1337" ],
    "workers": 2,
    "ttl": 20,
    "queries": [
        { "dname": "google.com", "blocked": 0, "type": "AAAA" },
        { "dname": "vk.com",     "blocked": 1, "type": "A" }
    ]
}

UDP and TCP

dnstress is able to work with both UDP and TCP protocols. Which one to use (or both) is defined in the command line arguments. See Stress test modes for more information.

Custom queries

In the config file you can specify which queries will be used for stressing. You can specify them as follows:

    "queries": [
        { "dname": "google.com", "blocked": 0, "type": "AAAA" },
        { "dname": "vk.com",     "blocked": 1, "type": "A" }
    ]

Some (happy) little explanation of object fields:

Field	Description
dname	domain name string used for request
blocked	1 if domain should be blocked by DNS server (only for statistics), 0 otherwise
type	type of request (A, AAAA, etc) for this specific domain name

Stress test modes

There are several executing modes that can be specified in the command line arguments before running dnstress. It's important to notice that every request is taken from the config file based on a stress test mode. All available modes are listed below:

Mode	Description
udp-valid	UDP requests with `blocked` flag equals `0`
tcp-valid	TCP requests with `blocked` flag equals `0`
udp-nonvalid	UDP requests with `blocked` flag equals `1`
tcp-nonvalid	TCP requests with `blocked` flag equals `1`
shuffle	random choice of a query from the config file

Several DNS servers

dnstress supports specifying a list of DNS servers. It is useful when your DNS server has several addresses and you want to check if all of them work correctly.

In the configuration file you can specify DNS server addresses as follows:

"addrs": [ "127.0.0.2", "127.0.0.3", "[2a0d:b600:166:ff00:e2d5:5eff:fe3a:a880]:1337" ]

Notice that you can specify ports as well!

Workers

In the configuration file you can also specify number of workers. Worker here is a process that was forked from the parent process of dnstress. The more workers you specify, the more requests you will be producing.

Speify number of workers in the json config like that:

"workers": 2

There is some limitation on the number of workers: from 1 to 10

TTL

ttl option allows you to specify the duration of a stressing (in seconds). If you specify ttl equals 0, then is means endless loop of sending requests. In this case you should stop dnstress by yourself.

"ttl": 20

Of course, you still can stop dnstress in any time as well.

How to build

Before building dnstress, take a look at the requirements section. When all libraries are installed, type the next in the terminal to build or rebuild dnstress:

$ make clean && make

How to run and use

To list all supported command line arguments, type --help:

$ ./dnstress --help

Usage: dnstress [OPTION...] 
A program that provides performance stress tests for defined DNS servers.

  -c, --config=CONFIG        file with dnstress configuration
  -l, --ld-lvl=LD-LVL        load level. from 1 to 10
  -m, --mode=MODE            mode for traffic generating (low-valid by
                             default)
                               • udp-valid:    UDP valid packets
                               • tcp-valid:    TCP valid packets
                               • udp-nonvalid: UDP non-valid (to be blocked)
                             packets
                               • tcp-nonvalid: TCP non-valid (to be blocked)
                             packets
                               • shuffle: random packets generating

  -o, --output=OUTFILE       Output to OUTFILE instead of to standard output
  -r, --rps=RPS              number of requests per second
  -v, --verbose              produce verbose output
  -?, --help                 Give this help list
      --usage                Give a short usage message
  -V, --version              Print program version

As you can see, help is self-documented. You need to just specify desired options when you run dnstress. Defualt mode is udp-valid. Run it like this:

$ ./dnstress --m shuffle -r 1000


Enter Ctrl+C to stop dnstress

[+] process workers are starting...

proc-worker: 0 | starting dnstress...
proc-worker: 1 | starting dnstress...

After you stop dnstress, all collected statistics will be printed on the screen. For example, this can be:

   STRESS STATISTIC
    ├─ 127.0.0.2
    │    ├─── UDP
    │    │    ├── NETWORK
    │    │    │   ├─ queries:   1200
    │    │    │   ├─ responses: 770
    │    │    │   └─ loss:      35.83%
    │    │    │          
    │    │    └── RESPONSE CODES
    │    │        ├─ noerr:     770
    │    │        ├─ corrupted: 0
    │    │        ├─ formaerr:  0
    │    │        ├─ servfail:  0
    │    │        └─ errors:    0.00%
    │    │               
    │    └─── TCP
    │         ├── NETWORK
    │         │   ├─ queries:   1200
    │         │   ├─ responses: 1163
    │         │   └─ loss:      3.08%
    │         │          
    │         └── RESPONSE CODES
    │             ├─ noerr:     1163
    │             ├─ corrupted: 0
    │             ├─ formaerr:  0
    │             ├─ servfail:  0
    │             └─ errors:    0.00%
    │                   
    └─ [2a0d:b600:166:ff00:e2d5:5eff:fe3a:a880]:1337
         ├─── UDP
         │    ├── NETWORK
         │    │   ├─ queries:   1200
         │    │   ├─ responses: 770
         │    │   └─ loss:      35.83%
         │    │          
         │    └── RESPONSE CODES
         │        ├─ noerr:     770
         │        ├─ corrupted: 0
         │        ├─ formaerr:  0
         │        ├─ servfail:  0
         │        └─ errors:    0.00%
         │               
         └─── TCP
              ├── NETWORK
              │   ├─ queries:   1200
              │   ├─ responses: 653
              │   └─ loss:      45.58%
              │          
              └── RESPONSE CODES
                  ├─ noerr:     653
                  ├─ corrupted: 0
                  ├─ formaerr:  0
                  ├─ servfail:  0
                  └─ errors:    0.00%

Where are logs

All logs are stored in syslog. Thus, you can observe them in runtime using the next command:

tail -f /var/log/syslog | grep dnstress

Requirements

These libraries are necessary for building:

Report Problems or Request for New Features

If you find any problem or bug, submit an issue about this problem. Also, if you think that a feature will be a nice addition to dnstress, do the same -- submit an issue and we will try to add your requested feature as soon as possible.

TODO

Add an option to control intensity of stressing (for instance, number of requests per second)
Add an option for verbose or compressed output
Change default path to dnstress configuration file
Debian package