126 lines
6.4 KiB
Markdown
126 lines
6.4 KiB
Markdown
# endlessh-go
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A golang implementation of [endlessh](https://nullprogram.com/blog/2019/03/22/) exporting Prometheus metrics, visualized by a Grafana dashboard.
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## Introduction
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[Endlessh](https://nullprogram.com/blog/2019/03/22/) is a great idea that not only blocks the brute force SSH attacks, but also wastes attackers time as a kind of counter-attack. Besides trapping the attackers, I also want to visualize the Geolocations and other statistics of the sources of attacks. Unfortunately the wonderful original [C implementation of endlessh](https://github.com/skeeto/endlessh) only provides text based log, but I do not like the solution that writes extra scripts to parse the log outputs, then exports the results to a dashboard, because it would introduce extra layers in my current setup and it would depend on the format of the text log file rather than some structured data. Thus I create this golang implementation of endlessh to export [Prometheus](https://prometheus.io/) metrics and a [Grafana](https://grafana.com/) dashboard to visualize them.
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If you want a dashboard of sources of attacks and do not mind the endlessh server, besides trapping the attackers, does extra things including: translating IP to Geohash, exporting Prometheus metrics, and using more memory (about 10MB), this is the solution for you.
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## Getting Started
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Clone the repo then build from source:
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```
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go build .
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./endlessh-go &
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```
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Alternatively, you can use the [docker image](https://hub.docker.com/r/shizunge/endlessh-go):
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```
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docker run -d -p 2222:2222 shizunge/endlessh-go -logtostderr -v=1
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```
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It listens to port `2222` by default.
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Then you can try to connect to the endlessh server. Your SSH client should hang there.
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```
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ssh -p 2222 localhost
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```
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If you want log like the [C implementation](https://github.com/skeeto/endlessh), you need to set both CLI arguments `-logtostderr` and `-v=1`, then the log will go to stderr. You can set different log destinations via CLI arguments.
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Also check out [examples](./examples/README.md) for the setup of the full stack.
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## Usage
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`./endlessh-go --help`
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```
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Usage of ./endlessh-go
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-alsologtostderr
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log to standard error as well as files
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-conn_type string
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Connection type. Possible values are tcp, tcp4, tcp6 (default "tcp")
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-enable_prometheus
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Enable prometheus
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-geoip_supplier string
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Supplier to obtain Geohash of IPs. Possible values are "off", "ip-api", "max-mind-db" (default "off")
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-host string
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SSH listening address (default "0.0.0.0")
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-interval_ms int
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Message millisecond delay (default 1000)
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-line_length int
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Maximum banner line length (default 32)
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-log_backtrace_at value
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when logging hits line file:N, emit a stack trace
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-log_dir string
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If non-empty, write log files in this directory
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-log_link string
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If non-empty, add symbolic links in this directory to the log files
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-logbuflevel int
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Buffer log messages logged at this level or lower (-1 means don't buffer; 0 means buffer INFO only; ...). Has limited applicability on non-prod platforms.
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-logtostderr
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log to standard error instead of files
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-max_clients int
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Maximum number of clients (default 4096)
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-max_mind_db string
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Path to the MaxMind DB file.
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-port value
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SSH listening port. You may provide multiple -port flags to listen to multiple ports. (default "2222")
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-prometheus_clean_unseen_seconds int
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Remove series if the IP is not seen for the given time. Set to 0 to disable. (default 0)
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-prometheus_entry string
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Entry point for prometheus (default "metrics")
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-prometheus_host string
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The address for prometheus (default "0.0.0.0")
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-prometheus_port string
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The port for prometheus (default "2112")
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-stderrthreshold value
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logs at or above this threshold go to stderr (default 2)
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-v value
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log level for V logs
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-vmodule value
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comma-separated list of pattern=N settings for file-filtered logging
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```
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## Metrics
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Endlessh-go exports the following Prometheus metrics.
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| Metric | Type | Description |
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| endlessh_client_open_count_total | count | Total number of clients that tried to connect to this host. |
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| endlessh_client_closed_count_total | count | Total number of clients that stopped connecting to this host. |
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| endlessh_sent_bytes_total | count | Total bytes sent to clients that tried to connect to this host. |
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| endlessh_trapped_time_seconds_total | count | Total seconds clients spent on endlessh. |
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| endlessh_client_open_count | count | Number of connections of clients. <br> Labels: <br> <ul><li> `ip`: Remote IP of the client </li> <li> `local_port`: Local port the program listens to </li> <li> `country`: Country of the IP </li> <li> `location`: Country, Region, and City </li> <li> `geohash`: Geohash of the location </li></ul> |
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| endlessh_client_trapped_time_seconds | count | Seconds a client spends on endlessh. <br> Labels: <br> <ul><li> `ip`: Remote IP of the client </li> <li> `local_port`: Local port the program listens to </li></ul> |
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The metrics is off by default, you can turn it via the CLI argument `-enable_prometheus`.
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It listens to port `2112` and entry point is `/metrics` by default. The port and entry point can be changed via CLI arguments.
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The endlessh-go server stores the geohash of attackers as a label on `endlessh_client_open_count`, which is also off by default. You can turn it on via the CLI argument `-geoip_supplier`. The endlessh-go uses service from [ip-api](https://ip-api.com/), which may enforce a query rate and limit commercial use. Visit their website for their terms and policies.
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You could also use an offline GeoIP database from [MaxMind](https://www.maxmind.com) by setting `-geoip_supplier` to _max-mind-db_ and `-max_mind_db` to the path of the database file.
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## Dashboard
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The dashboard requires Grafana 8.2.
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You can import the dashboard from Grafana.com using ID [15156](https://grafana.com/grafana/dashboards/15156)
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The dashboard visualizes data for the selected time range.
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The IP addresses are clickable and link you to the [ARIN](https://www.arin.net/) database.
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## Contacts
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If you have any problems or questions, please contact me through a [GitHub issue](https://github.com/shizunge/endlessh-go/issues)
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