Blackhole Experiment
The Blackhole experiment drops inbound and outbound network traffic. You can specify the type of traffic to impact by hostname, port, IP address, and additional arguments.
Blackhole drops IP packets at the transport layer (Layer 4) of the OSI model. This includes TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) traffic. Like most network experiments, Blackhole does not impact traffic to and from api.gremlin.com by default. This allows the agent to communicate with the Gremlin Control Plane during an experiment. It does not impact DNS traffic for this same reason. If you want to drop DNS traffic, use the DNS experiment.
Options
| Parameter |
Flag |
Default |
Version |
Description |
| IP Addresses |
-i IP address |
|
0.0.1 |
Only impact traffic to these IP addresses. Also accepts CIDR values (i.e.
10.0.0.0/24
).
|
| Device |
-d interfaces |
Device discovery |
0.0.1 |
Impact traffic over these network interfaces. Comma separated lists and multiple arguments supported.
You can define multiple interfaces starting with agent version 2.30.0. |
| Hostnames |
-h hostnames |
^api.gremlin.com
|
0.0.1 |
Only impact traffic to these hostnames. |
| Remote Ports |
-p port numbers |
^53
|
0.0.1 |
Impact outgoing and incoming traffic to and from these remote ports. Also accepts port ranges (e.g.
8080-8085
).
|
| Local Ports |
-n port numbers |
|
0.0.1 |
Impact outgoing and incoming traffic to and from these local ports. Also accepts port ranges (e.g.
8080-8085
).
|
| Protocol |
-P {TCP, UDP, ICMP} |
all |
1.5.3 |
Only impact a specific protocol. |
| Providers |
WebUI and API Only |
|
0.0.1 |
External service providers to affect. |
| Tags |
WebUI and API Only |
|
0.0.1 |
Only impact traffic to hosts running Gremlin clients associated with these tags. |
| Don't Derive Exclusion Rules |
-E |
2.51.1 |
Alternatively: --no-derived-exclusion-rules.
When this flag is not supplied, Gremlin will exclude its connection to api.gremlin.com, including
intermediate proxies. This option disables that behavior.
|
| Length |
-l int |
60
|
0.0.1 |
The length of the experiment (). |
Platform-specific notes
Linux
On Linux, Gremlin uses traffic policing features built into the Linux kernel to drop matching IP packets. This experiment requires the NET_ADMIN capability, which is enabled by default at installation time. See capabilities(7).
Windows
On Windows, Gremlin uses the Windows Filtering Platform to drop targeted IP packets.
Privileges required
| Privilege |
Description |
| FAULT_BLACKHOLE | Allows performing blackhole experiments |
