endlessh-go

A golang implementation of endlessh exporting Prometheus metrics, visualized by a Grafana dashboard.

Introduction

Endlessh 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 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 metrics and a Grafana dashboard to visualize them.

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.

Getting Started

Clone the repo then build from source:

go build .
./endlessh-go &

Alternatively, you can use the docker image:

docker run -d -p 2222:2222 shizunge/endlessh-go -logtostderr -v=1

It listens to port 2222 by default.

Then you can try to connect to the endlessh server. Your SSH client should hang there.

ssh -p 2222 localhost

If you want log like the C implementation, 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.

Also check out examples for the setup of the full stack.

Usage

./endlessh-go --help

Usage of ./endlessh-go
  -alsologtostderr
        log to standard error as well as files
  -conn_type string
        Connection type. Possible values are tcp, tcp4, tcp6 (default "tcp")
  -enable_prometheus
        Enable prometheus
  -geoip_supplier string
        Supplier to obtain Geohash of IPs. Possible values are "off", "ip-api", "max-mind-db" (default "off")
  -host string
        SSH listening address (default "0.0.0.0")
  -interval_ms int
        Message millisecond delay (default 1000)
  -line_length int
        Maximum banner line length (default 32)
  -log_backtrace_at value
        when logging hits line file:N, emit a stack trace
  -log_dir string
        If non-empty, write log files in this directory
  -log_link string
        If non-empty, add symbolic links in this directory to the log files
  -logbuflevel int
        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.
  -logtostderr
        log to standard error instead of files
  -max_clients int
        Maximum number of clients (default 4096)
  -max_mind_db string
        Path to the MaxMind DB file.
  -port value
        SSH listening port. You may provide multiple -port flags to listen to multiple ports. (default "2222")
  -prometheus_clean_unseen_seconds int
        Remove series if the IP is not seen for the given time. Set to 0 to disable. (default 0)
  -prometheus_entry string
        Entry point for prometheus (default "metrics")
  -prometheus_host string
        The address for prometheus (default "0.0.0.0")
  -prometheus_port string
        The port for prometheus (default "2112")
  -stderrthreshold value
        logs at or above this threshold go to stderr (default 2)
  -v value
        log level for V logs
  -vmodule value
        comma-separated list of pattern=N settings for file-filtered logging

Metrics

Endlessh-go exports the following Prometheus metrics.

Metric	Type	Description
endlessh_client_open_count_total	count	Total number of clients that tried to connect to this host.
endlessh_client_closed_count_total	count	Total number of clients that stopped connecting to this host.
endlessh_sent_bytes_total	count	Total bytes sent to clients that tried to connect to this host.
endlessh_trapped_time_seconds_total	count	Total seconds clients spent on endlessh.
endlessh_client_open_count	count	Number of connections of clients. Labels: ip: Remote IP of the client local_port: Local port the program listens to country: Country of the IP location: Country, Region, and City geohash: Geohash of the location
endlessh_client_trapped_time_seconds	count	Seconds a client spends on endlessh. Labels: ip: Remote IP of the client local_port: Local port the program listens to

The metrics is off by default, you can turn it via the CLI argument -enable_prometheus.

It listens to port 2112 and entry point is /metrics by default. The port and entry point can be changed via CLI arguments.

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, which may enforce a query rate and limit commercial use. Visit their website for their terms and policies.

You could also use an offline GeoIP database from MaxMind by setting -geoip_supplier to max-mind-db and -max_mind_db to the path of the database file.

Dashboard

The dashboard requires Grafana 8.2.

You can import the dashboard from Grafana.com using ID 15156

The dashboard visualizes data for the selected time range.

The IP addresses are clickable and link you to the ARIN database.

Contacts

If you have any problems or questions, please contact me through a GitHub issue