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Sim by rConfig Sim by rConfig rcfg-sim

rcfg-sim Quickstart

This walks you from a clean checkout to a running simulator you can SSH into — 100 devices on loopback, no root required. For a production 50k install see Installation.

Prerequisites

Section titled “Prerequisites”
  • Go 1.24+ (go version)
  • git, make
  • An SSH client, plus sshpass and curl for the test steps

1. Build the binaries

Section titled “1. Build the binaries”
Terminal window
git clone https://github.com/rconfig/rconfig-sim.git
cd rconfig-sim
make build

This produces two static binaries in bin/:

  • rcfg-sim-gen — the config generator
  • rcfg-sim — the SSH server

2. Generate 100 device configs

Section titled “2. Generate 100 device configs”
Terminal window
./bin/rcfg-sim-gen \
  --count 100 \
  --output-dir /tmp/rcfg-test/configs \
  --manifest /tmp/rcfg-test/manifest.csv \
  --ip-base 127.0.0.1 \
  --ip-count 1 \
  --port-start 12000 \
  --devices-per-ip 100 \
  --seed 42

This renders 100 .cfg files and a manifest.csv that maps each ip:port to its config, credentials, and driver. See Generating configs.

3. Run the server on loopback

Section titled “3. Run the server on loopback”
Terminal window
./bin/rcfg-sim \
  --listen-ip 127.0.0.1 \
  --port-start 12000 \
  --port-count 100 \
  --manifest /tmp/rcfg-test/manifest.csv \
  --host-key /tmp/rcfg-test/hostkey \
  --metrics-addr 127.0.0.1:9100

The server binds ports 12000–12099, generates an SSH host key if one is missing, and starts serving. Leave it running in this terminal.

4. SSH into a simulated device

Section titled “4. SSH into a simulated device”

In a second terminal, drive a full Cisco IOS session. The default credentials are admin / admin, enable password enable123.

Terminal window
sshpass -p admin ssh -T \
  -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null \
  admin@127.0.0.1 -p 12000 <<'CMDS'
terminal length 0
enable
enable123
show version
show running-config
exit
exit
CMDS

You will see the IOS greeting, a show version block, and the full running-config streamed back. (Two exits: the first leaves enable mode, the second closes the session.)

5. Scrape the metrics

Section titled “5. Scrape the metrics”
Terminal window
curl -s http://127.0.0.1:9100/metrics | grep -E '^rcfgsim_'

You should see counters move — rcfgsim_sessions_total, rcfgsim_bytes_sent_total, rcfgsim_command_duration_seconds, and more. See Metrics.

Next steps

Section titled “Next steps”