snmp-elixir

An SNMP client library for Elixir.

This is my effort to replace the terrible but useful net-snmp-elixir with a facile Elixir wrapper for OTP's harrowing SNMP API.

Many thanks to Dave Martin for his post, without which I may never have bothered returning to this problem.

Usage in CLI

iex> SNMP.start
iex>
iex> v2_cred =
...>   SNMP.credential(
...>     %{version: :v2, community: "public"}
...>   )
%SNMP.CommunityCredential{
  community: 'public',
  sec_model: :v2c,
  version: :v2
}
iex>
iex> {:ok, base_oid} =
...>   SNMP.resolve_object_name_to_oid(:sysName)
{:ok, [1, 3, 6, 1, 2, 1, 1, 5]}
iex>
iex> %{uri: URI.parse("snmp://an-snmp-host.local"),
...>   credential: v2_cred,
...>   varbinds: [%{oid: base_oid ++ [0]}],
...> } |> SNMP.request
{ :ok,
  [ %{oid: [1, 3, 6, 1, 2, 1, 1, 5, 0],
      type: :"OCTET STRING",
      value: "an-snmp-host"
    }
  ]
}
iex>
iex> v3_cred =
...>   SNMP.credential(
...>     %{version: :v3,
...>       sec_name: "user",
...>       auth: :sha,
...>       auth_pass: "authpass",
...>       priv: :aes,
...>       priv_pass: "privpass",
...>     }
...>  )
%SNMP.USMCredential{
  auth: :sha,
  auth_pass: 'authpass',
  priv: :aes,
  priv_pass: 'privpass',
  sec_level: :authPriv,
  sec_model: :usm,
  sec_name: 'nms',
  version: :v3
}
iex> %{uri: URI.parse("snmp://an-snmp-host.local"),
...>   credential: v3_cred,
...>   varbinds: [%{oid: "ipAddrTable"}],
...> } |> SNMP.walk
...> |> Enum.take(1)
[ %{oid: [1, 3, 6, 1, 2, 1, 4, 20, 1, 1, 192, 0, 2, 1],
    type: :IpAddress,
    value: [192, 0, 2, 1],
  }
]

Installation

Add :snmp_ex to mix.exs:

defp deps do
  [ { :snmp_ex, "~> 0.4.0" } ]
end

Any of the following defaults may be overridden in your config.exs.

config :snmp_ex,
  timeout: 5000,
  max_repetitions: 10,
  engine_discovery_timeout: 1000,
  mib_cache:      "priv/snmp/mibs",
  snmp_conf_dir:  "priv/snmp/conf",
  snmpm_conf_dir: "priv/snmp",
  snmpc_verbosity: "silence",
  mib_sources: ["/usr/share/snmp/mibs"]

snmpc_verbosity can be set to different values, see the erlang docs on which values you can use.

Finally, ensure the :snmp OTP application is available in your development environment. Some Linux distributions, such as CentOS, provide separate packages for individual OTP services and tools. Check for erlang-snmp if this is a concern. As for production, the release process will ensure :snmp is automatically included in the resulting tarball.

Why another wrapper?

net-snmp-elixir was my experimental hack to get something that worked. I didn't expect it to become one of the top Google results for "elixir snmp" but it is, which scares me. Elixir may be the best language for network interaction in existence, but we still need worthy SNMP support.

Contributing

This project will accept (merge/rebase/squash) all contributions. Contributions that break the build will be reverted.

For details, please see Why Optimistic Merging Works Better.

TODO

• SNMPv3 USM (AES support requires OTP >=23; see corresponding pull request for details.)
• USM engine discovery
• SNMP tables
• MIB name resolution
• Basic SNMP operations (GET, GET-NEXT, WALK, SET)
• Bulk SNMP operations
• Process management (supervision, :snmpm agents)
• Make it decent