Configuration¶
Paramiko does not itself leverage OpenSSH-style config file directives, but it does implement a parser for the format, which users can honor themselves (and is used by higher-level libraries, such as Fabric).
The API for this is SSHConfig
, which loads SSH config files from disk,
file-like object, or string and exposes a “look up a hostname, get a dict of
applicable keywords/values back” functionality.
As with OpenSSH’s own support, this dict will contain values from across the
parsed file, depending on the order in which keywords were encountered and how
specific or generic the Host
or Match
directives were.
Keywords currently supported¶
The following is an alphabetical list of which ssh_config directives Paramiko interprets during the parse/lookup process (as above, actual SSH connections do not reference parsed configs). Departures from OpenSSH’s implementation (e.g. to support backwards compat with older Paramiko releases) are included. A keyword by itself means no known departures.
AddressFamily
: used when looking up the local hostname for purposes of expanding the%l
/%L
tokens (this is actually a minor value-add on top of OpenSSH, which doesn’t actually honor this setting when expanding%l
).CanonicalDomains
New in version 2.7.
CanonicalizeFallbackLocal
: whenno
, triggers raising ofCouldNotCanonicalize
for target hostnames which do not successfully canonicalize.New in version 2.7.
CanonicalizeHostname
: along with the otherCanonicaliz*
settings (sansCanonicalizePermittedCNAMEs
, which is not yet implemented), enables hostname canonicalization, insofar as callingSSHConfig.lookup
with a given hostname will return a canonicalized copy of the config data, including an updatedHostName
value.New in version 2.7.
CanonicalizeMaxDots
New in version 2.7.
Host
HostName
: used in%h
token expansionMatch
: supports the keywordsall
,canonical
,exec
,final
,host
,localuser
,originalhost
, anduser
, with the following caveats:You must have the optional dependency Invoke installed; see the installation docs (in brief: install
paramiko[invoke]
orparamiko[all]
).As usual, connection-time information is not present during config lookup, and thus cannot be used to determine matching. This primarily impacts
Match user
, which can match against loadedUser
values but has no knowledge about connection-time usernames.
New in version 2.7.
Changed in version 3.3: Added support for the
final
keyword.Port
: supplies potential values for%p
token expansion.ProxyCommand
: see ourProxyCommand
class for an easy way to honor this keyword from a config you’ve parsed.Honors token expansion.
When a lookup would result in an effective
ProxyCommand none
, Paramiko (as of 1.x-2.x) strips it from the resulting dict entirely. A later major version may retain the"none"
marker for clarity’s sake.
User
: supplies potential values for%u
token expansion.
Expansion tokens¶
We support most SSH config expansion tokens where possible, so when they are
present in a config file source, the result of a SSHConfig.lookup
will
contain the expansions/substitutions (based on the rest of the config or
properties of the local system).
Specifically, we are known to support the below, where applicable (e.g. as in
OpenSSH, %L
works in ControlPath
but not elsewhere):
%C
%d
%h
%l
%L
%n
%p
%r
%u
: substitutes the configuredUser
value, or the local user (as seen bygetpass.getuser
) if not specified.
In addition, we extend OpenSSH’s tokens as follows:
~
is treated like%d
(expands to the local user’s home directory path) when expandingProxyCommand
values, sinceProxyCommand
does not natively support%d
for some reason.
config
module API documentation¶
Mostly of interest to contributors; see previous section for behavioral details.
Configuration file (aka ssh_config
) support.
- class paramiko.config.SSHConfig¶
Representation of config information as stored in the format used by OpenSSH. Queries can be made via
lookup
. The format is described in OpenSSH’sssh_config
man page. This class is provided primarily as a convenience to posix users (since the OpenSSH format is a de-facto standard on posix) but should work fine on Windows too.New in version 1.6.
- __init__()¶
Create a new OpenSSH config object.
Note: the newer alternate constructors
from_path
,from_file
andfrom_text
are simpler to use, as they parse on instantiation. For example, instead of:config = SSHConfig() config.parse(open("some-path.config")
you could:
config = SSHConfig.from_file(open("some-path.config")) # Or more directly: config = SSHConfig.from_path("some-path.config") # Or if you have arbitrary ssh_config text from some other source: config = SSHConfig.from_text("Host foo\n\tUser bar")
- classmethod from_path(path)¶
Create a new, parsed
SSHConfig
from the file found atpath
.New in version 2.7.
- classmethod from_file(flo)¶
Create a new, parsed
SSHConfig
from file-like objectflo
.New in version 2.7.
- parse(file_obj)¶
Read an OpenSSH config from the given file object.
- Parameters
file_obj – a file-like object to read the config file from
- lookup(hostname)¶
Return a dict (
SSHConfigDict
) of config options for a given hostname.The host-matching rules of OpenSSH’s
ssh_config
man page are used: For each parameter, the first obtained value will be used. The configuration files contain sections separated byHost
and/orMatch
specifications, and that section is only applied for hosts which match the given patterns or keywordsSince the first obtained value for each parameter is used, more host- specific declarations should be given near the beginning of the file, and general defaults at the end.
The keys in the returned dict are all normalized to lowercase (look for
"port"
, not"Port"
. The values are processed according to the rules for substitution variable expansion inssh_config
.Finally, please see the docs for
SSHConfigDict
for deeper info on features such as optional type conversion methods, e.g.:conf = my_config.lookup('myhost') assert conf['passwordauthentication'] == 'yes' assert conf.as_bool('passwordauthentication') is True
Note
If there is no explicitly configured
HostName
value, it will be set to the being-looked-up hostname, which is as close as we can get to OpenSSH’s behavior around that particular option.- Parameters
hostname (str) – the hostname to lookup
Changed in version 2.5: Returns
SSHConfigDict
objects instead of dict literals.Changed in version 2.7: Added canonicalization support.
Changed in version 2.7: Added
Match
support.Changed in version 3.3: Added
Match final
support.
- canonicalize(hostname, options, domains)¶
Return canonicalized version of
hostname
.- Parameters
hostname (str) – Target hostname.
options – An
SSHConfigDict
from a previous lookup pass.domains – List of domains (e.g.
["paramiko.org"]
).
- Returns
A canonicalized hostname if one was found, else
None
.
New in version 2.7.
- get_hostnames()¶
Return the set of literal hostnames defined in the SSH config (both explicit hostnames and wildcard entries).
- __weakref__¶
list of weak references to the object (if defined)
- class paramiko.config.LazyFqdn(config, host=None)¶
Returns the host’s fqdn on request as string.
- __init__(config, host=None)¶
- __str__()¶
Return str(self).
- __weakref__¶
list of weak references to the object (if defined)
- class paramiko.config.SSHConfigDict¶
A dictionary wrapper/subclass for per-host configuration structures.
This class introduces some usage niceties for consumers of
SSHConfig
, specifically around the issue of variable type conversions: normal value access yields strings, but there are now methods such asas_bool
andas_int
that yield casted values instead.For example, given the following
ssh_config
file snippet:Host foo.example.com PasswordAuthentication no Compression yes ServerAliveInterval 60
the following code highlights how you can access the raw strings as well as usefully Python type-casted versions (recalling that keys are all normalized to lowercase first):
my_config = SSHConfig() my_config.parse(open('~/.ssh/config')) conf = my_config.lookup('foo.example.com') assert conf['passwordauthentication'] == 'no' assert conf.as_bool('passwordauthentication') is False assert conf['compression'] == 'yes' assert conf.as_bool('compression') is True assert conf['serveraliveinterval'] == '60' assert conf.as_int('serveraliveinterval') == 60
New in version 2.5.
- as_bool(key)¶
Express given key’s value as a boolean type.
Typically, this is used for
ssh_config
’s pseudo-boolean values which are either"yes"
or"no"
. In such cases,"yes"
yieldsTrue
and any other value becomesFalse
.Note
If (for whatever reason) the stored value is already boolean in nature, it’s simply returned.
New in version 2.5.
- __weakref__¶
list of weak references to the object (if defined)