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snmp.py
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#!/usr/bin/env python3
#
# Copyright (C) 2018-2020 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import os
from binascii import hexlify
from time import sleep
from stat import S_IRWXU, S_IXGRP, S_IXOTH, S_IROTH, S_IRGRP
from sys import exit
from vyos.config import Config
from vyos.validate import is_ipv4, is_addr_assigned
from vyos.version import get_version_data
from vyos import ConfigError
from vyos.util import call
from vyos.template import render
config_file_client = r'/etc/snmp/snmp.conf'
config_file_daemon = r'/etc/snmp/snmpd.conf'
config_file_access = r'/usr/share/snmp/snmpd.conf'
config_file_user = r'/var/lib/snmp/snmpd.conf'
default_script_dir = r'/config/user-data/'
# SNMP OIDs used to mark auth/priv type
OIDs = {
'md5' : '.1.3.6.1.6.3.10.1.1.2',
'sha' : '.1.3.6.1.6.3.10.1.1.3',
'aes' : '.1.3.6.1.6.3.10.1.2.4',
'des' : '.1.3.6.1.6.3.10.1.2.2',
'none': '.1.3.6.1.6.3.10.1.2.1'
}
default_config_data = {
'listen_on': [],
'listen_address': [],
'ipv6_enabled': 'True',
'communities': [],
'smux_peers': [],
'location' : '',
'description' : '',
'contact' : '',
'trap_source': '',
'trap_targets': [],
'vyos_user': '',
'vyos_user_pass': '',
'version': '999',
'v3_enabled': 'False',
'v3_engineid': '',
'v3_groups': [],
'v3_traps': [],
'v3_users': [],
'v3_views': [],
'script_ext': []
}
def rmfile(file):
if os.path.isfile(file):
os.unlink(file)
def get_config():
snmp = default_config_data
conf = Config()
if not conf.exists('service snmp'):
return None
else:
if conf.exists('system ipv6 disable'):
snmp['ipv6_enabled'] = False
conf.set_level('service snmp')
version_data = get_version_data()
snmp['version'] = version_data['version']
# create an internal snmpv3 user of the form 'vyosxxxxxxxxxxxxxxxx'
# os.urandom(8) returns 8 bytes of random data
snmp['vyos_user'] = 'vyos' + hexlify(os.urandom(8)).decode('utf-8')
snmp['vyos_user_pass'] = hexlify(os.urandom(16)).decode('utf-8')
if conf.exists('community'):
for name in conf.list_nodes('community'):
community = {
'name': name,
'authorization': 'ro',
'network_v4': [],
'network_v6': [],
'has_source' : False
}
if conf.exists('community {0} authorization'.format(name)):
community['authorization'] = conf.return_value('community {0} authorization'.format(name))
# Subnet of SNMP client(s) allowed to contact system
if conf.exists('community {0} network'.format(name)):
for addr in conf.return_values('community {0} network'.format(name)):
if is_ipv4(addr):
community['network_v4'].append(addr)
else:
community['network_v6'].append(addr)
# IP address of SNMP client allowed to contact system
if conf.exists('community {0} client'.format(name)):
for addr in conf.return_values('community {0} client'.format(name)):
if is_ipv4(addr):
community['network_v4'].append(addr)
else:
community['network_v6'].append(addr)
if (len(community['network_v4']) > 0) or (len(community['network_v6']) > 0):
community['has_source'] = True
snmp['communities'].append(community)
if conf.exists('contact'):
snmp['contact'] = conf.return_value('contact')
if conf.exists('description'):
snmp['description'] = conf.return_value('description')
if conf.exists('listen-address'):
for addr in conf.list_nodes('listen-address'):
port = '161'
if conf.exists('listen-address {0} port'.format(addr)):
port = conf.return_value('listen-address {0} port'.format(addr))
snmp['listen_address'].append((addr, port))
# Always listen on localhost if an explicit address has been configured
# This is a safety measure to not end up with invalid listen addresses
# that are not configured on this system. See https://phabricator.vyos.net/T850
if not '127.0.0.1' in conf.list_nodes('listen-address'):
snmp['listen_address'].append(('127.0.0.1', '161'))
if not '::1' in conf.list_nodes('listen-address'):
snmp['listen_address'].append(('::1', '161'))
if conf.exists('location'):
snmp['location'] = conf.return_value('location')
if conf.exists('smux-peer'):
snmp['smux_peers'] = conf.return_values('smux-peer')
if conf.exists('trap-source'):
snmp['trap_source'] = conf.return_value('trap-source')
if conf.exists('trap-target'):
for target in conf.list_nodes('trap-target'):
trap_tgt = {
'target': target,
'community': '',
'port': ''
}
if conf.exists('trap-target {0} community'.format(target)):
trap_tgt['community'] = conf.return_value('trap-target {0} community'.format(target))
if conf.exists('trap-target {0} port'.format(target)):
trap_tgt['port'] = conf.return_value('trap-target {0} port'.format(target))
snmp['trap_targets'].append(trap_tgt)
#
# 'set service snmp script-extensions'
#
if conf.exists('script-extensions'):
for extname in conf.list_nodes('script-extensions extension-name'):
conf_script = conf.return_value('script-extensions extension-name {} script'.format(extname))
# if script has not absolute path, use pre configured path
if "/" not in conf_script:
conf_script = default_script_dir + conf_script
extension = {
'name': extname,
'script' : conf_script
}
snmp['script_ext'].append(extension)
#########################################################################
# ____ _ _ __ __ ____ _____ #
# / ___|| \ | | \/ | _ \ __ _|___ / #
# \___ \| \| | |\/| | |_) | \ \ / / |_ \ #
# ___) | |\ | | | | __/ \ V / ___) | #
# |____/|_| \_|_| |_|_| \_/ |____/ #
# #
# now take care about the fancy SNMP v3 stuff, or bail out eraly #
#########################################################################
if not conf.exists('v3'):
return snmp
else:
snmp['v3_enabled'] = True
# 'set service snmp v3 engineid'
if conf.exists('v3 engineid'):
snmp['v3_engineid'] = conf.return_value('v3 engineid')
# 'set service snmp v3 group'
if conf.exists('v3 group'):
for group in conf.list_nodes('v3 group'):
v3_group = {
'name': group,
'mode': 'ro',
'seclevel': 'auth',
'view': ''
}
if conf.exists('v3 group {0} mode'.format(group)):
v3_group['mode'] = conf.return_value('v3 group {0} mode'.format(group))
if conf.exists('v3 group {0} seclevel'.format(group)):
v3_group['seclevel'] = conf.return_value('v3 group {0} seclevel'.format(group))
if conf.exists('v3 group {0} view'.format(group)):
v3_group['view'] = conf.return_value('v3 group {0} view'.format(group))
snmp['v3_groups'].append(v3_group)
# 'set service snmp v3 trap-target'
if conf.exists('v3 trap-target'):
for trap in conf.list_nodes('v3 trap-target'):
trap_cfg = {
'ipAddr': trap,
'secName': '',
'authProtocol': 'md5',
'authPassword': '',
'authMasterKey': '',
'privProtocol': 'des',
'privPassword': '',
'privMasterKey': '',
'ipProto': 'udp',
'ipPort': '162',
'type': '',
'secLevel': 'noAuthNoPriv'
}
if conf.exists('v3 trap-target {0} user'.format(trap)):
# Set the securityName used for authenticated SNMPv3 messages.
trap_cfg['secName'] = conf.return_value('v3 trap-target {0} user'.format(trap))
if conf.exists('v3 trap-target {0} auth type'.format(trap)):
# Set the authentication protocol (MD5 or SHA) used for authenticated SNMPv3 messages
# cmdline option '-a'
trap_cfg['authProtocol'] = conf.return_value('v3 trap-target {0} auth type'.format(trap))
if conf.exists('v3 trap-target {0} auth plaintext-key'.format(trap)):
# Set the authentication pass phrase used for authenticated SNMPv3 messages.
# cmdline option '-A'
trap_cfg['authPassword'] = conf.return_value('v3 trap-target {0} auth plaintext-key'.format(trap))
if conf.exists('v3 trap-target {0} auth encrypted-key'.format(trap)):
# Sets the keys to be used for SNMPv3 transactions. These options allow you to set the master authentication keys.
# cmdline option '-3m'
trap_cfg['authMasterKey'] = conf.return_value('v3 trap-target {0} auth encrypted-key'.format(trap))
if conf.exists('v3 trap-target {0} privacy type'.format(trap)):
# Set the privacy protocol (DES or AES) used for encrypted SNMPv3 messages.
# cmdline option '-x'
trap_cfg['privProtocol'] = conf.return_value('v3 trap-target {0} privacy type'.format(trap))
if conf.exists('v3 trap-target {0} privacy plaintext-key'.format(trap)):
# Set the privacy pass phrase used for encrypted SNMPv3 messages.
# cmdline option '-X'
trap_cfg['privPassword'] = conf.return_value('v3 trap-target {0} privacy plaintext-key'.format(trap))
if conf.exists('v3 trap-target {0} privacy encrypted-key'.format(trap)):
# Sets the keys to be used for SNMPv3 transactions. These options allow you to set the master encryption keys.
# cmdline option '-3M'
trap_cfg['privMasterKey'] = conf.return_value('v3 trap-target {0} privacy encrypted-key'.format(trap))
if conf.exists('v3 trap-target {0} protocol'.format(trap)):
trap_cfg['ipProto'] = conf.return_value('v3 trap-target {0} protocol'.format(trap))
if conf.exists('v3 trap-target {0} port'.format(trap)):
trap_cfg['ipPort'] = conf.return_value('v3 trap-target {0} port'.format(trap))
if conf.exists('v3 trap-target {0} type'.format(trap)):
trap_cfg['type'] = conf.return_value('v3 trap-target {0} type'.format(trap))
# Determine securityLevel used for SNMPv3 messages (noAuthNoPriv|authNoPriv|authPriv).
# Appropriate pass phrase(s) must provided when using any level higher than noAuthNoPriv.
if trap_cfg['authPassword'] or trap_cfg['authMasterKey']:
if trap_cfg['privProtocol'] or trap_cfg['privPassword']:
trap_cfg['secLevel'] = 'authPriv'
else:
trap_cfg['secLevel'] = 'authNoPriv'
snmp['v3_traps'].append(trap_cfg)
# 'set service snmp v3 user'
if conf.exists('v3 user'):
for user in conf.list_nodes('v3 user'):
user_cfg = {
'name': user,
'authMasterKey': '',
'authPassword': '',
'authProtocol': 'md5',
'authOID': 'none',
'group': '',
'mode': 'ro',
'privMasterKey': '',
'privPassword': '',
'privOID': '',
'privProtocol': 'des'
}
# v3 user {0} auth
if conf.exists('v3 user {0} auth encrypted-key'.format(user)):
user_cfg['authMasterKey'] = conf.return_value('v3 user {0} auth encrypted-key'.format(user))
if conf.exists('v3 user {0} auth plaintext-key'.format(user)):
user_cfg['authPassword'] = conf.return_value('v3 user {0} auth plaintext-key'.format(user))
# load default value
type = user_cfg['authProtocol']
if conf.exists('v3 user {0} auth type'.format(user)):
type = conf.return_value('v3 user {0} auth type'.format(user))
# (re-)update with either default value or value from CLI
user_cfg['authProtocol'] = type
user_cfg['authOID'] = OIDs[type]
# v3 user {0} group
if conf.exists('v3 user {0} group'.format(user)):
user_cfg['group'] = conf.return_value('v3 user {0} group'.format(user))
# v3 user {0} mode
if conf.exists('v3 user {0} mode'.format(user)):
user_cfg['mode'] = conf.return_value('v3 user {0} mode'.format(user))
# v3 user {0} privacy
if conf.exists('v3 user {0} privacy encrypted-key'.format(user)):
user_cfg['privMasterKey'] = conf.return_value('v3 user {0} privacy encrypted-key'.format(user))
if conf.exists('v3 user {0} privacy plaintext-key'.format(user)):
user_cfg['privPassword'] = conf.return_value('v3 user {0} privacy plaintext-key'.format(user))
# load default value
type = user_cfg['privProtocol']
if conf.exists('v3 user {0} privacy type'.format(user)):
type = conf.return_value('v3 user {0} privacy type'.format(user))
# (re-)update with either default value or value from CLI
user_cfg['privProtocol'] = type
user_cfg['privOID'] = OIDs[type]
snmp['v3_users'].append(user_cfg)
# 'set service snmp v3 view'
if conf.exists('v3 view'):
for view in conf.list_nodes('v3 view'):
view_cfg = {
'name': view,
'oids': []
}
if conf.exists('v3 view {0} oid'.format(view)):
for oid in conf.list_nodes('v3 view {0} oid'.format(view)):
oid_cfg = {
'oid': oid
}
view_cfg['oids'].append(oid_cfg)
snmp['v3_views'].append(view_cfg)
return snmp
def verify(snmp):
if snmp is None:
# we can not delete SNMP when LLDP is configured with SNMP
conf = Config()
if conf.exists('service lldp snmp enable'):
raise ConfigError('Can not delete SNMP service, as LLDP still uses SNMP!')
return None
### check if the configured script actually exist
if snmp['script_ext']:
for ext in snmp['script_ext']:
if not os.path.isfile(ext['script']):
print ("WARNING: script: {} doesn't exist".format(ext['script']))
else:
os.chmod(ext['script'], S_IRWXU | S_IXGRP | S_IXOTH | S_IROTH | S_IRGRP)
for listen in snmp['listen_address']:
addr = listen[0]
port = listen[1]
if is_ipv4(addr):
# example: udp:127.0.0.1:161
listen = 'udp:' + addr + ':' + port
elif snmp['ipv6_enabled']:
# example: udp6:[::1]:161
listen = 'udp6:' + '[' + addr + ']' + ':' + port
# We only wan't to configure addresses that exist on the system.
# Hint the user if they don't exist
if is_addr_assigned(addr):
snmp['listen_on'].append(listen)
else:
print('WARNING: SNMP listen address {0} not configured!'.format(addr))
# bail out early if SNMP v3 is not configured
if not snmp['v3_enabled']:
return None
if 'v3_groups' in snmp.keys():
for group in snmp['v3_groups']:
#
# A view must exist prior to mapping it into a group
#
if 'view' in group.keys():
error = True
if 'v3_views' in snmp.keys():
for view in snmp['v3_views']:
if view['name'] == group['view']:
error = False
if error:
raise ConfigError('You must create view "{0}" first'.format(group['view']))
else:
raise ConfigError('"view" must be specified')
if not 'mode' in group.keys():
raise ConfigError('"mode" must be specified')
if not 'seclevel' in group.keys():
raise ConfigError('"seclevel" must be specified')
if 'v3_traps' in snmp.keys():
for trap in snmp['v3_traps']:
if trap['authPassword'] and trap['authMasterKey']:
raise ConfigError('Must specify only one of encrypted-key/plaintext-key for trap auth')
if trap['authPassword'] == '' and trap['authMasterKey'] == '':
raise ConfigError('Must specify encrypted-key or plaintext-key for trap auth')
if trap['privPassword'] and trap['privMasterKey']:
raise ConfigError('Must specify only one of encrypted-key/plaintext-key for trap privacy')
if trap['privPassword'] == '' and trap['privMasterKey'] == '':
raise ConfigError('Must specify encrypted-key or plaintext-key for trap privacy')
if not 'type' in trap.keys():
raise ConfigError('v3 trap: "type" must be specified')
if not 'authPassword' and 'authMasterKey' in trap.keys():
raise ConfigError('v3 trap: "auth" must be specified')
if not 'authProtocol' in trap.keys():
raise ConfigError('v3 trap: "protocol" must be specified')
if not 'privPassword' and 'privMasterKey' in trap.keys():
raise ConfigError('v3 trap: "user" must be specified')
if 'v3_users' in snmp.keys():
for user in snmp['v3_users']:
#
# Group must exist prior to mapping it into a group
# seclevel will be extracted from group
#
if user['group']:
error = True
if 'v3_groups' in snmp.keys():
for group in snmp['v3_groups']:
if group['name'] == user['group']:
seclevel = group['seclevel']
error = False
if error:
raise ConfigError('You must create group "{0}" first'.format(user['group']))
# Depending on the configured security level
# the user has to provide additional info
if user['authPassword'] and user['authMasterKey']:
raise ConfigError('Can not mix "encrypted-key" and "plaintext-key" for user auth')
if (not user['authPassword'] and not user['authMasterKey']):
raise ConfigError('Must specify encrypted-key or plaintext-key for user auth')
if user['privPassword'] and user['privMasterKey']:
raise ConfigError('Can not mix "encrypted-key" and "plaintext-key" for user privacy')
if user['privPassword'] == '' and user['privMasterKey'] == '':
raise ConfigError('Must specify encrypted-key or plaintext-key for user privacy')
if user['mode'] == '':
raise ConfigError('Must specify user mode ro/rw')
if 'v3_views' in snmp.keys():
for view in snmp['v3_views']:
if not view['oids']:
raise ConfigError('Must configure an oid')
return None
def generate(snmp):
#
# As we are manipulating the snmpd user database we have to stop it first!
# This is even save if service is going to be removed
call('systemctl stop snmpd.service')
config_files = [config_file_client, config_file_daemon, config_file_access,
config_file_user]
for file in config_files:
rmfile(file)
if snmp is None:
return None
# Write client config file
render(config_file_client, 'snmp/etc.snmp.conf.tmpl', snmp)
# Write server config file
render(config_file_daemon, 'snmp/etc.snmpd.conf.tmpl', snmp)
# Write access rights config file
render(config_file_access, 'snmp/usr.snmpd.conf.tmpl', snmp)
# Write access rights config file
render(config_file_user, 'snmp/var.snmpd.conf.tmpl', snmp)
return None
def apply(snmp):
if snmp is None:
return None
# start SNMP daemon
call("systemctl restart snmpd.service")
# Passwords are not available immediately in the configuration file,
# after daemon startup - we wait until they have been processed by
# snmpd, which we see when a magic line appears in this file.
while True:
while not os.path.exists(config_file_user):
sleep(0.5)
try:
with open(config_file_user, 'r') as f:
for line in f:
# Search for our magic string inside the file
if 'usmUser' in line:
break
except IOError:
continue
else:
break
# net-snmp is now regenerating the configuration file in the background
# thus we need to re-open and re-read the file as the content changed.
# After that we can no read the encrypted password from the config and
# replace the CLI plaintext password with its encrypted version.
os.environ["vyos_libexec_dir"] = "/usr/libexec/vyos"
with open(config_file_user, 'r') as f:
engineID = ''
for line in f:
if line.startswith('usmUser'):
string = line.split(' ')
cfg = {
'user': string[4].replace(r'"', ''),
'auth_pw': string[8],
'priv_pw': string[10]
}
# No need to take care about the VyOS internal user
if cfg['user'] == snmp['vyos_user']:
continue
# Now update the running configuration
#
# Currently when executing call() the environment does not
# have the vyos_libexec_dir variable set, see Phabricator T685.
call('/opt/vyatta/sbin/my_set service snmp v3 user "{0}" auth encrypted-key "{1}" > /dev/null'.format(cfg['user'], cfg['auth_pw']))
call('/opt/vyatta/sbin/my_set service snmp v3 user "{0}" privacy encrypted-key "{1}" > /dev/null'.format(cfg['user'], cfg['priv_pw']))
call('/opt/vyatta/sbin/my_delete service snmp v3 user "{0}" auth plaintext-key > /dev/null'.format(cfg['user']))
call('/opt/vyatta/sbin/my_delete service snmp v3 user "{0}" privacy plaintext-key > /dev/null'.format(cfg['user']))
# Enable AgentX in FRR
call('vtysh -c "configure terminal" -c "agentx" >/dev/null')
return None
if __name__ == '__main__':
try:
c = get_config()
verify(c)
generate(c)
apply(c)
except ConfigError as e:
print(e)
exit(1)

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