Automatically change ssh config file when you connect to different networks
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#!/usr/bin/env python3
#
import configparser
import json
import logging
import os
import re
import subprocess
import sys
import syslog
#
class SSHConfiger:
#
_action_interface = None
_action_command = None
#
_config_file_path = None
_targets = None
_config = None
#
def __init__(self, action_interface, action_command, config_file_path):
# Grab args
self._action_interface = action_interface
self._action_command = action_command
self._config_file_path = config_file_path
#
def log(self, s):
#
print ("[SSHConfiger]", s)
syslog.syslog("[SSHConfiger] " + s)
#
def complain(self, s):
#
syslog.syslog(syslog.LOG_ERR, "[SSHConfiger] " + s)
print("[SSHConfiger]", s, file=sys.stderr)
#
def die(self, s):
#
self.complain(s)
raise Exception(s)
def quit(self, s):
#
self.log("Quitting because: " + s)
sys.exit(0)
#
def run(self):
#
self.log("Running for interface \""+ self._action_interface +"\": " + self._action_command)
# Only run if an interface is coming up
if ( self._action_command != "up" ):
self.quit("We don't need to run for action command: " + str(self._action_command))
# Parse the config
self.parse_config()
# Grab the specified ssh directory
if ( "ssh_dir" not in self._config.keys() ):
self.die("Config file needs key \"ssh_dir\" inside \"config\" section")
ssh_dir = self._config["ssh_dir"]
self.log("SSH Dir: " + str(ssh_dir))
# Determine which ssh config file we should use
ssh_config_name = self.determine_ssh_config_name()
self.log("Determined ssh config name: " + str(ssh_config_name))
if not ssh_config_name:
self.die("Unable to determine appropriate ssh config name; Quitting")
# Make paths
ssh_config_path_link = os.path.join(ssh_dir, "config")
ssh_config_path_target = os.path.join(ssh_dir, ssh_config_name)
self.log("Selecting source config file \"" + ssh_config_path_target + "\" for link \"" + ssh_config_path_link + "\"")
# Don't run unless current ssh config is a symlink or not a file (for safety)
self.require_symlink_or_none(ssh_config_path_link)
# Set the symlink
try:
os.unlink(ssh_config_path_link)
except:
pass
os.symlink(ssh_config_path_target, ssh_config_path_link)
#
self.log("Finished")
#
def require_symlink_or_none(self, file_path):
#
if ( not os.path.isfile(file_path) or os.path.islink(file_path) ):
return True
#
self.die("For safety, we cannot continue if the target link exists and is a file (" + file_path + ")")
#
def determine_ssh_config_name(self):
#
self.log("Attempting to determine SSH config name")
# Check each section
found_ssh_config_name = None
for section_name in self._targets:
#
section = self._targets[section_name]
self.log("Examining section: " + str(section_name))
# Don't examine default if anything is picked already
if section_name == "default" and found_ssh_config_name:
self.log("Skipping default section because we've already found at least one match: " + str(found_ssh_config_name))
continue
# Check the interface
interface_matched = False
if (
# Matches, if current interface found in adapters
self._action_interface in section["adapters"]
# Can also match if we're in section "default"
or section_name == "default"
):
interface_matched = True
if not interface_matched:
self.log("Section \"" + str(section_name) + "\" didn't match any interfaces; Skipping")
continue
# Grab the SSID this adapter is currently connected to
interface_ssid = self.get_interface_ssid(self._action_interface)
if not interface_ssid:
self.log("Interface \"" + str(interface_ssid) + "\" isn't connected to anything ... ")
self.log("Interface \"" + str(self._action_interface) + "\" is currently connected to: \"" + str(interface_ssid) + "\"")
# Must also match at least one SSID,
# OR we're in the default section
if interface_ssid not in section["ssids"] and section_name != "default":
self.log("Did not find SSID \"" + interface_ssid + "\" in section ssids: " + str(section["ssids"]))
continue
# Found a match!
found_ssh_config_name = section["ssh_config_name"]
self.log("Found matching ssh config name: " + str(found_ssh_config_name))
# Didn't find anything? Go default ...
if (not found_ssh_config_name):
if ( "default" in self._targets.keys() ):
if ( "ssh_config_name" in self._targets["default"].keys() ):
found_ssh_config_name = self._targets["default"]["ssh_config_name"]
self.log("No matches found; Defaulting to:" + found_ssh_config_name)
#
return found_ssh_config_name
#
def get_interface_ssid(self, interface):
#
p = subprocess.Popen(["nmcli", "dev", "show", interface], stdout=subprocess.PIPE)
(stdout, stderr) = p.communicate()
stdout = stdout.decode()
#
r = re.compile("""^GENERAL.CONNECTION:\s+(?P<ssid>[^\s].+)$""", re.MULTILINE)
match = r.search(stdout)
return match.group("ssid")
#
def parse_config(self):
#
self.log("Parsing config: " + self._config_file_path)
parser = configparser.ConfigParser()
parser.read( self._config_file_path )
# Attempt to grab global config
if ( "config" not in parser.sections() ):
self.die("config section not found")
config = parser["config"]
# Targets
targets = {}
for section in parser.sections():
# Skip the config section
if ( section == "config" ):
continue
#
self.log("Parsing config target: \"" + section + "\"")
target = {
"adapters" : [],
"ssids" : []
}
# Adapters
if ( parser.has_option(section, "adapters") ):
target["adapters"] = json.loads( parser[section]["adapters"] )
if ( parser.has_option(section, "adapter") ):
target["adapters"].append( parser[section]["adapter"] )
# SSIDs
if ( parser.has_option(section, "ssids") ):
target["ssids"] = json.loads( parser[section]["ssids"] )
if ( parser.has_option(section, "ssid") ):
target["ssids"].append( parser[section]["ssid"] )
# ssh_config_name
if ( parser.has_option(section, "ssh_config_name") ):
target["ssh_config_name"] = parser[section]["ssh_config_name"]
else:
raise Exception("ssh_config_name key missing from section: " + section)
#
targets[section] = target
self.log("Parsed config for config target \"" + section + "\": " + str(target))
#
self._config = config
self._targets = targets
return True
# Main Entry
if (__name__ == "__main__"):
# Script name
script_name = sys.argv[0]
# Network Manager action info
action_interface = sys.argv[1]
action_command = sys.argv[2]
# Config file
config_file_path = sys.argv[3]
#
configger = SSHConfiger(action_interface, action_command, config_file_path)
configger.run()