cloudstack/scripts/vm/network/security_group.py

#!/usr/bin/python
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.

import cloud_utils
from subprocess import check_output, CalledProcessError
from cloudutils.configFileOps import configFileOps
import logging
import sys
import os
import xml.dom.minidom
from optparse import OptionParser, OptionGroup, OptParseError, BadOptionError, OptionError, OptionConflictError, OptionValueError
import re
import libvirt
import fcntl
import time
from netaddr import IPAddress, IPNetwork
from netaddr.core import AddrFormatError


logpath = "/var/run/cloud/"        # FIXME: Logs should reside in /var/log/cloud
lock_file = "/var/lock/cloudstack_security_group.lock"
driver = "qemu:///system"
cfo = configFileOps("/etc/cloudstack/agent/agent.properties")
hyper = cfo.getEntry("hypervisor.type")
if hyper == "lxc":
    driver = "lxc:///"

lock_handle = None


def obtain_file_lock(path):
    global lock_handle

    try:
        lock_handle = open(path, 'w')
        fcntl.flock(lock_handle, fcntl.LOCK_EX | fcntl.LOCK_NB)
        return True
    except IOError:
        pass

    return False


def execute(cmd):
    logging.debug(cmd)
    try:
        return check_output(cmd, shell=True)
    except CalledProcessError as e:
        pass


def can_bridge_firewall(privnic):
    try:
        execute("which iptables")
    except:
        print("no iptables on your host machine")
        sys.exit(1)

    try:
        execute("which ebtables")
    except:
        print("no ebtables on your host machine")
        sys.exit(2)


    if not os.path.exists(logpath):
        os.makedirs(logpath)

    cleanup_rules_for_dead_vms()
    cleanup_rules()

    return True


def virshlist(states):
    libvirt_states={ 'running'  : libvirt.VIR_DOMAIN_RUNNING,
                     'shutoff'  : libvirt.VIR_DOMAIN_SHUTOFF,
                     'shutdown' : libvirt.VIR_DOMAIN_SHUTDOWN,
                     'paused'   : libvirt.VIR_DOMAIN_PAUSED,
                     'nostate'  : libvirt.VIR_DOMAIN_NOSTATE,
                     'blocked'  : libvirt.VIR_DOMAIN_BLOCKED,
                     'crashed'  : libvirt.VIR_DOMAIN_CRASHED,
    }

    searchstates = list(libvirt_states[state] for state in states)

    conn = libvirt.openReadOnly(driver)
    if not conn:
       print('Failed to open connection to the hypervisor')
       sys.exit(3)

    alldomains = map(conn.lookupByID, conn.listDomainsID())
    alldomains += map(conn.lookupByName, conn.listDefinedDomains())

    domains = []
    for domain in alldomains:
        if domain.info()[0] in searchstates:
            domains.append(domain.name())

    conn.close()

    return domains


def virshdomstate(domain):
    libvirt_states={ libvirt.VIR_DOMAIN_RUNNING  : 'running',
                     libvirt.VIR_DOMAIN_SHUTOFF  : 'shut off',
                     libvirt.VIR_DOMAIN_SHUTDOWN : 'shut down',
                     libvirt.VIR_DOMAIN_PAUSED   : 'paused',
                     libvirt.VIR_DOMAIN_NOSTATE  : 'no state',
                     libvirt.VIR_DOMAIN_BLOCKED  : 'blocked',
                     libvirt.VIR_DOMAIN_CRASHED  : 'crashed',
    }

    conn = libvirt.openReadOnly(driver)
    if not conn:
       print('Failed to open connection to the hypervisor')
       sys.exit(3)

    try:
        dom = (conn.lookupByName (domain))
    except libvirt.libvirtError:
        return None

    state = libvirt_states[dom.info()[0]]
    conn.close()

    return state


def virshdumpxml(domain):
    conn = libvirt.openReadOnly(driver)
    if not conn:
       print('Failed to open connection to the hypervisor')
       sys.exit(3)

    try:
        dom = (conn.lookupByName (domain))
    except libvirt.libvirtError:
        return None

    xml = dom.XMLDesc(0)
    conn.close()

    return xml


def ipv6_link_local_addr(mac=None):
    eui64 = re.sub(r'[.:-]', '', mac).lower()
    eui64 = eui64[0:6] + 'fffe' + eui64[6:]
    eui64 = hex(int(eui64[0:2], 16) ^ 2)[2:].zfill(2) + eui64[2:]
    return IPAddress('fe80::' + ':'.join(re.findall(r'.{4}', eui64)))


def destroy_network_rules_for_vm(vm_name, vif=None):
    vmchain = iptables_chain_name(vm_name)
    vmchain_egress = egress_chain_name(vm_name)
    vmchain_default = None
    vm_ipsetname=ipset_chain_name(vm_name)

    delete_rules_for_vm_in_bridge_firewall_chain(vm_name)
    if vm_name.startswith('i-'):
        vmchain_default = '-'.join(vm_name.split('-')[:-1]) + "-def"

    destroy_ebtables_rules(vm_name, vif)

    chains = [vmchain_default, vmchain, vmchain_egress]
    for chain in filter(None, chains):
        try:
            execute("iptables -F " + chain)
            execute('ip6tables -F ' + chain)
        except:
            logging.debug("Ignoring failure to flush chain: " + chain)

    for chain in filter(None, chains):
        try:
            execute("iptables -X " + chain)
            execute('ip6tables -X ' + chain)
        except:
            logging.debug("Ignoring failure to delete chain: " + chain)

    try:
        for ipset in [vm_ipsetname, vm_ipsetname + '-6']:
            execute('ipset -F ' + ipset)
            execute('ipset -X ' + ipset)
    except:
        logging.debug("Ignoring failure to delete ipset " + vmchain)

    if vif:
        try:
            dnats = execute("""iptables -t nat -S | awk '/%s/ { sub(/-A/, "-D", $1) ; print }'""" % vif ).split("\n")
            for dnat in filter(None, dnats):
                try:
                    execute("iptables -t nat " + dnat)
                except:
                    logging.debug("Ignoring failure to delete dnat: " + dnat)
        except:
            pass
    remove_rule_log_for_vm(vm_name)
    remove_secip_log_for_vm(vm_name)

    if 1 in [ vm_name.startswith(c) for c in ['r-', 's-', 'v-'] ]:
        return True

    return True


def destroy_ebtables_rules(vm_name, vif):
    eb_vm_chain=ebtables_chain_name(vm_name)
    delcmd = "ebtables -t nat -L PREROUTING | grep " + eb_vm_chain
    delcmds = []
    try:
        delcmds = filter(None, execute(delcmd).split('\n'))
        delcmds = ["-D PREROUTING " + x for x in delcmds ]
    except:
        pass
    postcmds = []
    try:
        postcmd = "ebtables -t nat -L POSTROUTING | grep " + eb_vm_chain
        postcmds = filter(None, execute(postcmd).split('\n'))
        postcmds = ["-D POSTROUTING " + x for x in postcmds]
    except:
        pass

    delcmds += postcmds

    for cmd in delcmds:
        try:
            execute("ebtables -t nat " + cmd)
        except:
            logging.debug("Ignoring failure to delete ebtables rules for vm " + vm_name)
    chains = [eb_vm_chain+"-in", eb_vm_chain+"-out", eb_vm_chain+"-in-ips", eb_vm_chain+"-out-ips"]
    for chain in chains:
        try:
            execute("ebtables -t nat -F " + chain)
            execute("ebtables -t nat -X " + chain)
        except:
            logging.debug("Ignoring failure to delete ebtables chain for vm " + vm_name)


def default_ebtables_rules(vm_name, vm_ip, vm_mac, vif):
    eb_vm_chain=ebtables_chain_name(vm_name)
    vmchain_in = eb_vm_chain + "-in"
    vmchain_out = eb_vm_chain + "-out"
    vmchain_in_ips = eb_vm_chain + "-in-ips"
    vmchain_out_ips = eb_vm_chain + "-out-ips"

    for chain in [vmchain_in, vmchain_out, vmchain_in_ips, vmchain_out_ips]:
        try:
            execute("ebtables -t nat -N " + chain)
        except:
            execute("ebtables -t nat -F " + chain)

    try:
        # -s ! 52:54:0:56:44:32 -j DROP
        execute("ebtables -t nat -A PREROUTING -i " + vif + " -j " + vmchain_in)
        execute("ebtables -t nat -A POSTROUTING -o " + vif + " -j " + vmchain_out)
        execute("ebtables -t nat -A " + vmchain_in_ips + " -j DROP")
        execute("ebtables -t nat -A " + vmchain_out_ips + " -j DROP")
    except:
        logging.debug("Failed to program default rules")
        return False

    try:
        execute("ebtables -t nat -A " + vmchain_in + " -s ! " + vm_mac + " -j DROP")
        execute("ebtables -t nat -A " + vmchain_in + " -p ARP -s ! " + vm_mac + " -j DROP")
        execute("ebtables -t nat -A " + vmchain_in + " -p ARP --arp-mac-src ! " + vm_mac + " -j DROP")
        if vm_ip:
            execute("ebtables -t nat -A " + vmchain_in + " -p ARP -j " + vmchain_in_ips)
            execute("ebtables -t nat -I " + vmchain_in_ips + " -p ARP --arp-ip-src " + vm_ip + " -j RETURN")
        execute("ebtables -t nat -A " + vmchain_in + " -p ARP --arp-op Request -j ACCEPT")
        execute("ebtables -t nat -A " + vmchain_in + " -p ARP --arp-op Reply -j ACCEPT")
        execute("ebtables -t nat -A " + vmchain_in + " -p ARP -j DROP")
    except:
        logging.exception("Failed to program default ebtables IN rules")
        return False

    try:
        execute("ebtables -t nat -A " + vmchain_out + " -p ARP --arp-op Reply --arp-mac-dst ! " + vm_mac + " -j DROP")
        if vm_ip:
            execute("ebtables -t nat -A " + vmchain_out + " -p ARP -j " + vmchain_out_ips )
            execute("ebtables -t nat -I " + vmchain_out_ips + " -p ARP --arp-ip-dst " + vm_ip + " -j RETURN")
        execute("ebtables -t nat -A " + vmchain_out + " -p ARP --arp-op Request -j ACCEPT")
        execute("ebtables -t nat -A " + vmchain_out + " -p ARP --arp-op Reply -j ACCEPT")
        execute("ebtables -t nat -A " + vmchain_out + " -p ARP -j DROP")
    except:
        logging.debug("Failed to program default ebtables OUT rules")
        return False


def default_network_rules_systemvm(vm_name, localbrname):
    bridges = getBridges(vm_name)
    domid = getvmId(vm_name)
    vmchain = iptables_chain_name(vm_name)

    delete_rules_for_vm_in_bridge_firewall_chain(vm_name)

    try:
        execute("iptables -N " + vmchain)
    except:
        execute("iptables -F " + vmchain)

    for bridge in bridges:
        if bridge != localbrname:
            if not addFWFramework(bridge):
                return False
            brfw = getBrfw(bridge)
            vifs = getVifsForBridge(vm_name, bridge)
            for vif in vifs:
                try:
                    execute("iptables -A " + brfw + "-OUT" + " -m physdev --physdev-is-bridged --physdev-out " + vif + " -j " + vmchain)
                    execute("iptables -A " + brfw + "-IN" + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -j " + vmchain)
                    execute("iptables -A " + vmchain + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -j RETURN")
                except:
                    logging.debug("Failed to program default rules")
                    return False

    execute("iptables -A " + vmchain + " -j ACCEPT")

    if not write_rule_log_for_vm(vm_name, '-1', '_ignore_', domid, '_initial_', '-1'):
        logging.debug("Failed to log default network rules for systemvm, ignoring")
    return True


def remove_secip_log_for_vm(vmName):
    vm_name = vmName
    logfilename = logpath + vm_name + ".ip"

    result = True
    try:
        os.remove(logfilename)
    except:
        logging.debug("Failed to delete rule log file " + logfilename)
        result = False

    return result


def write_secip_log_for_vm (vmName, secIps, vmId):
    vm_name = vmName
    logfilename = logpath + vm_name + ".ip"
    logging.debug("Writing log to " + logfilename)
    logf = open(logfilename, 'w')
    output = ','.join([vmName, secIps, vmId])
    result = True

    try:
        logf.write(output)
        logf.write('\n')
    except:
        logging.debug("Failed to write to rule log file " + logfilename)
        result = False

    logf.close()

    return result


def create_ipset_forvm(ipsetname, type='iphash', family='inet'):
    result = True
    try:
        logging.debug("Creating ipset chain .... " + ipsetname)
        execute("ipset -F " + ipsetname)
        execute("ipset -X " + ipsetname)
    except:
        logging.debug("ipset chain not exists creating.... " + ipsetname)
    finally:
        execute('ipset -N ' + ipsetname + ' ' + type + ' family ' + family)

    return result


def add_to_ipset(ipsetname, ips, action):
    result = True
    for ip in ips:
        try:
            logging.debug("vm ip " + str(ip))
            execute("ipset " + action + " " + ipsetname + " " + str(ip))
        except:
            logging.debug("vm ip already in ip set " + str(ip))
            continue

    return result


def network_rules_vmSecondaryIp(vm_name, ip_secondary, action):
    logging.debug("vmName = "+ vm_name)
    logging.debug("action = "+ action)

    domid = getvmId(vm_name)

    vmchain = vm_name
    add_to_ipset(vmchain, [ip_secondary], action)

    #add ebtables rules for the secondary ip
    ebtables_rules_vmip(vm_name, [ip_secondary], action)

    return True


def ebtables_rules_vmip (vmname, ips, action):
    eb_vm_chain=ebtables_chain_name(vmname)
    vmchain_inips = eb_vm_chain + "-in-ips"
    vmchain_outips = eb_vm_chain + "-out-ips"

    if action and action.strip() == "-A":
        action = "-I"

    for ip in filter(None, ips):
        logging.debug("ip = " + ip)
        if ip == 0 or ip == "0":
            continue
        try:
            execute("ebtables -t nat " + action + " " + vmchain_inips + " -p ARP --arp-ip-src " + ip + " -j RETURN")
            execute("ebtables -t nat " + action + " " + vmchain_outips + " -p ARP --arp-ip-dst " + ip + " -j RETURN")
        except:
            logging.debug("Failed to program ebtables rules for secondary ip %s for vm %s with action %s" % (ip, vmname, action))


def default_network_rules(vm_name, vm_id, vm_ip, vm_ip6, vm_mac, vif, brname, sec_ips):
    if not addFWFramework(brname):
        return False

    vmName = vm_name
    brfw = getBrfw(brname)
    domID = getvmId(vm_name)
    delete_rules_for_vm_in_bridge_firewall_chain(vmName)
    vmchain = iptables_chain_name(vm_name)
    vmchain_egress = egress_chain_name(vm_name)
    vmchain_default = '-'.join(vmchain.split('-')[:-1]) + "-def"
    ipv6_link_local = ipv6_link_local_addr(vm_mac)

    destroy_ebtables_rules(vm_name, vif)

    for chain in [vmchain, vmchain_egress, vmchain_default]:
        try:
            execute('iptables -N ' + chain)
        except:
            execute('iptables -F ' + chain)

        try:
            execute('ip6tables -N ' + chain)
        except:
            execute('ip6tables -F ' + chain)

    action = "-A"
    vmipsetName = ipset_chain_name(vm_name)
    #create ipset and add vm ips to that ip set
    if not create_ipset_forvm(vmipsetName):
       logging.debug(" failed to create ipset for rule " + str(tokens))
       return False

    #add primary nic ip to ipset
    if not add_to_ipset(vmipsetName, [vm_ip], action ):
       logging.debug(" failed to add vm " + vm_ip + " ip to set ")
       return False

    #add secodnary nic ips to ipset
    secIpSet = "1"
    ips = sec_ips.split(';')
    ips.pop()
    if ips[0] == "0":
        secIpSet = "0"

    if secIpSet == "1":
        logging.debug("Adding ipset for secondary ips")
        add_to_ipset(vmipsetName, ips, action)
        if not write_secip_log_for_vm(vm_name, sec_ips, vm_id):
            logging.debug("Failed to log default network rules, ignoring")

    try:
        execute("iptables -A " + brfw + "-OUT" + " -m physdev --physdev-is-bridged --physdev-out " + vif + " -j " + vmchain_default)
        execute("iptables -A " + brfw + "-IN" + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -j " + vmchain_default)
        execute("iptables -A " + vmchain_default + " -m state --state RELATED,ESTABLISHED -j ACCEPT")
        #allow dhcp
        execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -p udp --dport 67 --sport 68 -j ACCEPT")
        execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-out " + vif + " -p udp --dport 68 --sport 67  -j ACCEPT")

        #don't let vm spoof its ip address
        if vm_ip:
            execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -m set ! --set " + vmipsetName + " src -j DROP")
            execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -m set --set " + vmipsetName + " src -p udp --dport 53  -j RETURN ")
            execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -m set --set " + vmipsetName + " src -p tcp --dport 53  -j RETURN ")
            execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-in " + vif + " -m set --set " + vmipsetName + " src -j " + vmchain_egress)
        execute("iptables -A " + vmchain_default + " -m physdev --physdev-is-bridged --physdev-out " + vif + " -j " + vmchain)
        execute("iptables -A " + vmchain + " -j DROP")
    except:
        logging.debug("Failed to program default rules for vm " + vm_name)
        return False

    default_ebtables_rules(vm_name, vm_ip, vm_mac, vif)
    #default ebtables rules for vm secondary ips
    ebtables_rules_vmip(vm_name, ips, "-I")

    if vm_ip:
        if not write_rule_log_for_vm(vmName, vm_id, vm_ip, domID, '_initial_', '-1'):
            logging.debug("Failed to log default network rules, ignoring")

    vm_ip6_set_name = vm_name + '-6'

    if not create_ipset_forvm(vm_ip6_set_name, family='inet6', type='hash:net'):
       logging.debug(" failed to create ivp6 ipset for rule " + str(tokens))
       return False

    vm_ip6_addr = [ipv6_link_local]
    try:
        ip6 = IPAddress(vm_ip6)
        if ip6.version == 6:
            vm_ip6_addr.append(ip6)
    except AddrFormatError:
        pass

    add_to_ipset(vm_ip6_set_name, vm_ip6_addr, action)

    try:
        execute('ip6tables -A ' + brfw + '-OUT' + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -j ' + vmchain_default)
        execute('ip6tables -A ' + brfw + '-IN' + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -j ' + vmchain_default)
        execute('ip6tables -A ' + vmchain_default + ' -m state --state RELATED,ESTABLISHED -j ACCEPT')

        # Allow Instances to receive Router Advertisements, send out solicitations, but block any outgoing Advertisement from a Instance
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' --src fe80::/64 --dst ff02::1 -p icmpv6 --icmpv6-type router-advertisement -m hl --hl-eq 255 -j ACCEPT')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' --dst ff02::2 -p icmpv6 --icmpv6-type router-solicitation -m hl --hl-eq 255 -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type router-advertisement -j DROP')

        # Allow neighbor solicitations and advertisements
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type neighbor-solicitation -m hl --hl-eq 255 -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p icmpv6 --icmpv6-type neighbor-solicitation -m hl --hl-eq 255 -j ACCEPT')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type neighbor-advertisement -m set --match-set ' + vm_ip6_set_name + ' src -m hl --hl-eq 255 -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p icmpv6 --icmpv6-type neighbor-advertisement -m hl --hl-eq 255 -j ACCEPT')

        # Packets to allow as per RFC4890
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type packet-too-big -m set --match-set ' + vm_ip6_set_name + ' src -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p icmpv6 --icmpv6-type packet-too-big -j ACCEPT')

        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type destination-unreachable -m set --match-set ' + vm_ip6_set_name + ' src -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p icmpv6 --icmpv6-type destination-unreachable -j ACCEPT')

        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type time-exceeded -m set --match-set ' + vm_ip6_set_name + ' src -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p icmpv6 --icmpv6-type time-exceeded -j ACCEPT')

        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --icmpv6-type parameter-problem -m set --match-set ' + vm_ip6_set_name + ' src -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p icmpv6 --icmpv6-type parameter-problem -j ACCEPT')

        # MLDv2 discovery packets
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p icmpv6 --dst ff02::16 -j RETURN')

        # Allow Instances to send out DHCPv6 client messages, but block server messages
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p udp --sport 546 --dst ff02::1:2 --src ' + str(ipv6_link_local) + ' -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -p udp --src fe80::/64 --dport 546 --dst ' + str(ipv6_link_local) + ' -j ACCEPT')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p udp --sport 547 ! --dst fe80::/64 -j DROP')

        # Always allow outbound DNS over UDP and TCP
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p udp --dport 53 -m set --match-set ' + vm_ip6_set_name + ' src -j RETURN')
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -p tcp --dport 53 -m set --match-set ' + vm_ip6_set_name + ' src -j RETURN')

        # Prevent source address spoofing
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -m set ! --match-set ' + vm_ip6_set_name + ' src -j DROP')

        # Send proper traffic to the egress chain of the Instance
        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-in ' + vif + ' -m set --match-set ' + vm_ip6_set_name + ' src -j ' + vmchain_egress)

        execute('ip6tables -A ' + vmchain_default + ' -m physdev --physdev-is-bridged --physdev-out ' + vif + ' -j ' + vmchain)

        # Drop all other traffic into the Instance
        execute('ip6tables -A ' + vmchain + ' -j DROP')
    except:
        logging.debug('Failed to program default rules for vm ' + vm_name)
        return False

    logging.debug("Programmed default rules for vm " + vm_name)
    return True


def post_default_network_rules(vm_name, vm_id, vm_ip, vm_mac, vif, brname, dhcpSvr, hostIp, hostMacAddr):
    vmchain_default = '-'.join(vm_name.split('-')[:-1]) + "-def"
    iptables_vmchain=iptables_chain_name(vm_name)
    vmchain_in = iptables_vmchain + "-in"
    vmchain_out = iptables_vmchain + "-out"
    domID = getvmId(vm_name)
    try:
        execute("iptables -I " + vmchain_default + " 4 -m physdev --physdev-is-bridged --physdev-in " + vif + " --source " + vm_ip + " -j ACCEPT")
    except:
        pass
    try:
        execute("iptables -t nat -A PREROUTING -p tcp -m physdev --physdev-in " + vif + " -m tcp --dport 80 -d " + dhcpSvr + " -j DNAT --to-destination " + hostIp + ":80")
    except:
        pass

    try:
        execute("ebtables -t nat -I " + vmchain_in + " -p IPv4 --ip-protocol tcp --ip-destination-port 80 --ip-dst " + dhcpSvr + " -j dnat --to-destination " + hostMacAddr)
    except:
        pass

    try:
        execute("ebtables -t nat -I " + vmchain_in + " 4 -p ARP --arp-ip-src ! " + vm_ip + " -j DROP")
    except:
        pass
    try:
        execute("ebtables -t nat -I " + vmchain_out + " 2 -p ARP --arp-ip-dst ! " + vm_ip + " -j DROP")
    except:
        pass
    if not write_rule_log_for_vm(vm_name, vm_id, vm_ip, domID, '_initial_', '-1'):
            logging.debug("Failed to log default network rules, ignoring")


def delete_rules_for_vm_in_bridge_firewall_chain(vmName):
    vm_name = vmName
    if vm_name.startswith('i-'):
        vm_name=iptables_chain_name(vm_name)
        vm_name = '-'.join(vm_name.split('-')[:-1]) + "-def"

    vmchain = iptables_chain_name(vm_name)

    delcmd = """iptables-save | awk '/BF(.*)physdev-is-bridged(.*)%s/ { sub(/-A/, "-D", $1) ; print }'""" % vmchain
    delcmds = filter(None, execute(delcmd).split('\n'))
    for cmd in delcmds:
        try:
            execute("iptables " + cmd)
        except:
              logging.exception("Ignoring failure to delete rules for vm " + vmName)

    delcmd = """ip6tables-save | awk '/BF(.*)physdev-is-bridged(.*)%s/ { sub(/-A/, "-D", $1) ; print }'""" % vmchain
    delcmds = filter(None, execute(delcmd).split('\n'))
    for cmd in delcmds:
        try:
            execute('ip6tables ' + cmd)
        except:
              logging.exception("Ignoring failure to delete rules for vm " + vmName)


def rewrite_rule_log_for_vm(vm_name, new_domid):
    logfilename = logpath + vm_name + ".log"
    if not os.path.exists(logfilename):
        return
    lines = (line.rstrip() for line in open(logfilename))

    [_vmName,_vmID,_vmIP,_domID,_signature,_seqno] = ['_', '-1', '_', '-1', '_', '-1']
    for line in lines:
        [_vmName,_vmID,_vmIP,_domID,_signature,_seqno] = line.split(',')
        break

    write_rule_log_for_vm(_vmName, _vmID, '0.0.0.0', new_domid, _signature, '-1')


def get_rule_log_for_vm(vmName):
    vm_name = vmName
    logfilename = logpath + vm_name + ".log"
    if not os.path.exists(logfilename):
        return ''

    lines = (line.rstrip() for line in open(logfilename))

    [_vmName,_vmID,_vmIP,_domID,_signature,_seqno] = ['_', '-1', '_', '-1', '_', '-1']
    for line in lines:
        [_vmName,_vmID,_vmIP,_domID,_signature,_seqno] = line.split(',')
        break

    return ','.join([_vmName, _vmID, _vmIP, _domID, _signature, _seqno])


def check_domid_changed(vmName):
    curr_domid = getvmId(vmName)
    if (curr_domid is None) or (not curr_domid.isdigit()):
        curr_domid = '-1'

    vm_name = vmName
    logfilename = logpath + vm_name + ".log"
    if not os.path.exists(logfilename):
        return ['-1', curr_domid]

    lines = (line.rstrip() for line in open(logfilename))

    [_vmName,_vmID,_vmIP,old_domid,_signature,_seqno] = ['_', '-1', '_', '-1', '_', '-1']
    for line in lines:
        [_vmName,_vmID,_vmIP,old_domid,_signature,_seqno] = line.split(',')
        break

    return [curr_domid, old_domid]


def network_rules_for_rebooted_vm(vmName):
    vm_name = vmName
    [curr_domid, old_domid] = check_domid_changed(vm_name)

    if curr_domid == old_domid:
        return True

    if old_domid == '-1':
        return True

    if curr_domid == '-1':
        return True

    logging.debug("Found a rebooted VM -- reprogramming rules for " + vm_name)

    delete_rules_for_vm_in_bridge_firewall_chain(vm_name)

    brName = execute("iptables-save | awk -F '-j ' '/FORWARD -o(.*)physdev-is-bridged(.*)BF/ {print $2}'").strip()
    if brName is None or brName is "":
        brName = "cloudbr0"
    else:
        brName = execute("iptables-save |grep physdev-is-bridged |grep FORWARD |grep BF |grep '\-o' |awk '{print $4}' | head -1").strip()

    if 1 in [ vm_name.startswith(c) for c in ['r-', 's-', 'v-'] ]:
        default_network_rules_systemvm(vm_name, brName)
        return True

    vmchain = iptables_chain_name(vm_name)
    vmchain_default = '-'.join(vmchain.split('-')[:-1]) + "-def"

    vifs = getVifs(vmName)
    logging.debug(vifs, brName)
    for v in vifs:
        execute("iptables -A " + getBrfw(brName) + "-IN " + " -m physdev --physdev-is-bridged --physdev-in " + v + " -j "+ vmchain_default)
        execute("iptables -A " + getBrfw(brName) + "-OUT " + " -m physdev --physdev-is-bridged --physdev-out " + v + " -j "+ vmchain_default)
        execute("ip6tables -A " + getBrfw(brName) + "-IN " + " -m physdev --physdev-is-bridged --physdev-in " + v + " -j " + vmchain_default)
        execute("ip6tables -A " + getBrfw(brName) + "-OUT " + " -m physdev --physdev-is-bridged --physdev-out " + v + " -j " + vmchain_default)

    #change antispoof rule in vmchain
    try:
        delcmd = """iptables-save | awk '/-A %s(.*)physdev/ { sub(/-A/, "-D", $1) ; print }'""" % vmchain_default
        inscmd = """iptables-save | awk '/-A %s(.*)physdev/ { gsub(/vnet[0-9]+/, "%s") ; sub(/-A/, "-D", $1) ; print }'""" % ( vmchain_default,vifs[0] )
        ipts = []
        for cmd in [delcmd, inscmd]:
            logging.debug(cmd)
            cmds = filter(None, execute(cmd).split('\n'))
            for c in cmds:
                    ipt = "iptables " + c
                    ipts.append(ipt)

        for ipt in ipts:
            try:
                execute(ipt)
            except:
                logging.debug("Failed to rewrite antispoofing rules for vm " + vm_name)
    except:
        logging.debug("No rules found for vm " + vm_name)

    rewrite_rule_log_for_vm(vm_name, curr_domid)
    return True


def get_rule_logs_for_vms():
    state=['running']
    vms = virshlist(state)

    result = []
    try:
        for name in vms:
            name = name.rstrip()
            if 1 not in [ name.startswith(c) for c in ['r-', 's-', 'v-', 'i-'] ]:
                continue
            network_rules_for_rebooted_vm(name)
            if name.startswith('i-'):
                log = get_rule_log_for_vm(name)
                result.append(log)
    except:
        logging.exception("Failed to get rule logs, better luck next time!")

    print(";".join(result))


def cleanup_rules_for_dead_vms():
    return True


def cleanup_bridge(bridge):
    bridge_name = getBrfw(bridge)
    logging.debug("Cleaning old bridge chains: " + bridge_name)
    if not bridge_name:
        return True

    # Delete iptables/bridge rules
    rules = execute("""iptables-save | grep %s | grep '^-A' | sed 's/-A/-D/' """ % bridge_name).split("\n")
    for rule in filter(None, rules):
        try:
            command = "iptables " + rule
            execute(command)
        except: pass

    chains = [bridge_name, bridge_name+'-IN', bridge_name+'-OUT']
    # Flush old bridge chain
    for chain in chains:
        try:
            execute("iptables -F " + chain)
        except: pass
    # Remove brige chains
    for chain in chains:
        try:
            execute("iptables -X " + chain)
        except: pass
    return True


def cleanup_rules():
    try:
        states=['running','paused']
        vmsInHost = virshlist(states)

        logging.debug(" Vms on the host : %s ", vmsInHost)

        cleanup = []
        chainscmd = """iptables-save | grep -P '^:(?!.*-(def|eg))' | awk '{sub(/^:/, "", $1) ; print $1}' | sort | uniq"""
        chains = execute(chainscmd).split('\n')

        logging.debug(" iptables chains in the host :%s ", chains)

        for chain in chains:
            if 1 in [ chain.startswith(c) for c in ['r-', 'i-', 's-', 'v-'] ]:
                vm_name = chain
                vmpresent=False

                for vm in vmsInHost:
                    if vm_name  in vm:
                        vmpresent=True
                        break

                if vmpresent is False:
                    logging.debug("vm " + vm_name + " is not running or paused, cleaning up iptables rules")
                    cleanup.append(vm_name)

        bridge_tables = execute("""grep -E '^ebtable_' /proc/modules | cut -f1 -d' ' | sed s/ebtable_//""").split('\n')
        for table in filter(None, bridge_tables):
            chainscmd = """ebtables -t %s -L | awk '/chain:/ { gsub(/(^.*chain: |-(in|out|ips).*)/, ""); print $1}' | sort | uniq""" % table
            chains = execute(chainscmd).split('\n')

        logging.debug(" ebtables chains in the host: %s ", chains)

        for chain in filter(None, chains):
            if 1 in [ chain.startswith(c) for c in ['r-', 'i-', 's-', 'v-'] ]:
                vm_name = chain
                vmpresent=False
                for vm in vmsInHost:
                    if vm_name  in vm:
                        vmpresent=True
                        break

                if vmpresent is False:
                    logging.debug("vm " + vm_name + " is not running or paused, cleaning up ebtables rules")
                    cleanup.append(vm_name)

        cleanup = list(set(cleanup))  # remove duplicates
        for vmname in cleanup:
            destroy_network_rules_for_vm(vmname)

        logging.debug("Cleaned up rules for " + str(len(cleanup)) + " chains")
    except:
        logging.debug("Failed to cleanup rules !")


def check_rule_log_for_vm(vmName, vmId, vmIP, domID, signature, seqno):
    vm_name = vmName
    logfilename = logpath + vm_name + ".log"
    if not os.path.exists(logfilename):
        return [True, True, True, True, True, True]

    try:
        lines = (line.rstrip() for line in open(logfilename))
    except:
        logging.debug("failed to open " + logfilename)
        return [True, True, True, True, True, True]

    [_vmName,_vmID,_vmIP,_domID,_signature,_seqno] = ['_', '-1', '_', '-1', '_', '-1']
    try:
        for line in lines:
            [_vmName,_vmID,_vmIP,_domID,_signature,_seqno] = line.split(',')
            break
    except:
        logging.debug("Failed to parse log file for vm " + vm_name)
        remove_rule_log_for_vm(vm_name)
        return [True, True, True, True, True, True]

    return [(vm_name != _vmName), (vmId != _vmID), (vmIP != _vmIP), (domID != _domID), (signature != _signature),(seqno != _seqno)]


def write_rule_log_for_vm(vmName, vmID, vmIP, domID, signature, seqno):
    vm_name = vmName
    logfilename = logpath + vm_name + ".log"
    logging.debug("Writing log to " + logfilename)
    logf = open(logfilename, 'w')
    output = ','.join([vmName, vmID, vmIP, str(domID), signature, seqno])
    result = True
    try:
        logf.write(output)
        logf.write('\n')
    except:
        logging.debug("Failed to write to rule log file " + logfilename)
        result = False

    logf.close()

    return result


def remove_rule_log_for_vm(vmName):
    vm_name = vmName
    logfilename = logpath + vm_name + ".log"

    result = True
    try:
        os.remove(logfilename)
    except:
        logging.debug("Failed to delete rule log file " + logfilename)
        result = False

    return result


#ebtables chain max len 31 char
def ebtables_chain_name(vm_name):
    # 23 because there are appends to the chains
    if len(vm_name) > 22:
        vm_name = vm_name[0:22]
    return vm_name


#ipset chain max len 31 char
def ipset_chain_name(vm_name):
    if len(vm_name) > 30:
        vm_name = vm_name[0:30]
    return vm_name


#iptables chain max len 29 char and it is appended with other names like -eg,-def
def iptables_chain_name(vm_name):
    if len(vm_name) > 25:
        vm_name = vm_name[0:24]
    return vm_name


def egress_chain_name(vm_name):
    chain_name = iptables_chain_name(vm_name)
    return chain_name + "-eg"


def parse_network_rules(rules):
  ret = []

  if rules is None or len(rules) == 0:
    return ret

  lines = rules.split('NEXT;')[:-1]
  for line in lines:
    tokens = line.split(';', 3)
    if len(tokens) != 4:
      continue

    ruletype, protocol = tokens[0].split(':')
    start = int(tokens[1])
    end = int(tokens[2])
    cidrs = tokens.pop()

    ipv4 = []
    ipv6 = []
    for ip in cidrs.split(","):
        try:
            network = IPNetwork(ip)
            if network.version == 4:
                ipv4.append(ip)
            else:
                ipv6.append(ip)
        except:
            pass

    ret.append({'ipv4': ipv4, 'ipv6': ipv6, 'ruletype': ruletype,
                'start': start, 'end': end, 'protocol': protocol})

  return ret


def add_network_rules(vm_name, vm_id, vm_ip, vm_ip6, signature, seqno, vmMac, rules, vif, brname, sec_ips):
  try:
    vmName = vm_name
    domId = getvmId(vmName)

    changes = check_rule_log_for_vm(vmName, vm_id, vm_ip, domId, signature, seqno)

    if not 1 in changes:
        logging.debug("Rules already programmed for vm " + vm_name)
        return True

    if changes[0] or changes[1] or changes[2] or changes[3]:
        default_network_rules(vmName, vm_id, vm_ip, vm_ip6, vmMac, vif, brname, sec_ips)

    logging.debug("    programming network rules for IP: " + vm_ip + " vmname=" + vm_name)

    egress_chain_name(vm_name)
    vmchain = iptables_chain_name(vm_name)
    egress_vmchain = egress_chain_name(vm_name)

    try:
      for chain in [vmchain, egress_vmchain]:
          execute('iptables -F ' + chain)
          execute('ip6tables -F ' + chain)
    except:
      logging.debug("Error flushing iptables rules for " + vm_name + ". Presuming firewall rules deleted, re-initializing." )
      default_network_rules(vm_name, vm_id, vm_ip, vm_ip6, vmMac, vif, brname, sec_ips)

    egressrule_v4 = 0
    egressrule_v6 = 0

    for rule in parse_network_rules(rules):
        start = rule['start']
        end = rule['end']
        protocol = rule['protocol']

        if rule['ruletype'] == 'E':
            vmchain = egress_vmchain
            direction = "-d"
            action = "RETURN"
            if rule['ipv4']:
                egressrule_v4 =+ 1

            if rule['ipv6']:
                egressrule_v6 +=1

        else:
            vmchain = vm_name
            action = "ACCEPT"
            direction = "-s"

        range = str(start) + ':' + str(end)
        if 'icmp' == protocol:
            range = str(start) + '/' + str(end)
            if start == -1:
                range = 'any'

        for ip in rule['ipv4']:
            if protocol == 'all':
                execute('iptables -I ' + vmchain + ' -m state --state NEW ' + direction + ' ' + ip + ' -j ' + action)
            elif protocol != 'icmp':
                execute('iptables -I ' + vmchain + ' -p ' + protocol + ' -m ' + protocol + ' --dport ' + range + ' -m state --state NEW ' + direction + ' ' + ip + ' -j ' + action)
            else:
                execute('iptables -I ' + vmchain + ' -p icmp --icmp-type ' + range + ' ' + direction + ' ' + ip + ' -j ' + action)

        for ip in rule['ipv6']:
            if protocol == 'all':
                execute('ip6tables -I ' + vmchain + ' -m state --state NEW ' + direction + ' ' + ip + ' -j ' + action)
            elif 'icmp' != protocol:
                execute('ip6tables -I ' + vmchain + ' -p ' + protocol + ' -m ' + protocol + ' --dport ' + range + ' -m state --state NEW ' + direction + ' ' + ip + ' -j ' + action)
            else:
                # ip6tables does not allow '--icmpv6-type any', allowing all ICMPv6 is done by not allowing a specific type
                if range == 'any':
                    execute('ip6tables -I ' + vmchain + ' -p icmpv6 ' + direction + ' ' + ip + ' -j ' + action)
                else:
                    execute('ip6tables -I ' + vmchain + ' -p icmpv6 --icmpv6-type ' + range + ' ' + direction + ' ' + ip + ' -j ' + action)

    egress_vmchain = egress_chain_name(vm_name)
    if egressrule_v4 == 0 :
        execute('iptables -A ' + egress_vmchain + ' -j RETURN')
    else:
        execute('iptables -A ' + egress_vmchain + ' -j DROP')

    if egressrule_v6 == 0 :
        execute('ip6tables -A ' + egress_vmchain + ' -j RETURN')
    else:
        execute('ip6tables -A ' + egress_vmchain + ' -j DROP')

    vmchain = iptables_chain_name(vm_name)

    execute('iptables -A ' + vmchain + ' -j DROP')
    execute('ip6tables -A ' + vmchain + ' -j DROP')

    if not write_rule_log_for_vm(vmName, vm_id, vm_ip, domId, signature, seqno):
        return False

    return True
  except:
    logging.exception("Failed to network rule !")


def getVifs(vmName):
    vifs = []
    xmlfile = virshdumpxml(vmName)
    if not xmlfile:
        return vifs

    dom = xml.dom.minidom.parseString(xmlfile)
    for network in dom.getElementsByTagName("interface"):
        target = network.getElementsByTagName('target')[0]
        nicdev = target.getAttribute("dev").strip()
        vifs.append(nicdev)
    return vifs


def getVifsForBridge(vmName, brname):
    vifs = []
    xmlfile = virshdumpxml(vmName)
    if not xmlfile:
        return vifs

    dom = xml.dom.minidom.parseString(xmlfile)
    for network in dom.getElementsByTagName("interface"):
        source = network.getElementsByTagName('source')[0]
        bridge = source.getAttribute("bridge").strip()
        if bridge == brname:
            target = network.getElementsByTagName('target')[0]
            nicdev = target.getAttribute("dev").strip()
            vifs.append(nicdev)
    return list(set(vifs))


def getBridges(vmName):
    bridges = []
    xmlfile = virshdumpxml(vmName)
    if not xmlfile:
        return bridges

    dom = xml.dom.minidom.parseString(xmlfile)
    for network in dom.getElementsByTagName("interface"):
        for source in network.getElementsByTagName('source'):
            bridge = source.getAttribute("bridge").strip()
            bridges.append(bridge)
    return list(set(bridges))


def getvmId(vmName):

    conn = libvirt.openReadOnly(driver)
    if not conn:
       print('Failed to open connection to the hypervisor')
       sys.exit(3)

    try:
        dom = (conn.lookupByName (vmName))
    except libvirt.libvirtError:
        return None

    conn.close()

    res = dom.ID()
    if isinstance(res, int):
        res = str(res)
    return res


def getBrfw(brname):
    cmd = "iptables-save |grep physdev-is-bridged |grep FORWARD |grep BF |grep '\-o' | grep -w " + brname  + "|awk '{print $9}' | head -1"
    brfwname = execute(cmd).strip()
    if not brfwname:
        brfwname = "BF-" + brname
    return brfwname


def addFWFramework(brname):
    try:
        execute("sysctl -w net.bridge.bridge-nf-call-arptables=1")
        execute("sysctl -w net.bridge.bridge-nf-call-iptables=1")
        execute("sysctl -w net.bridge.bridge-nf-call-ip6tables=1")
    except:
        logging.warn("failed to turn on bridge netfilter")

    brfw = getBrfw(brname)
    try:
        execute("iptables -L " + brfw)
    except:
        execute("iptables -N " + brfw)

    brfwout = brfw + "-OUT"
    try:
        execute("iptables -L " + brfwout)
    except:
        execute("iptables -N " + brfwout)

    brfwin = brfw + "-IN"
    try:
        execute("iptables -L " + brfwin)
    except:
        execute("iptables -N " + brfwin)

    try:
        execute('ip6tables -L ' + brfw)
    except:
        execute('ip6tables -N ' + brfw)

    brfwout = brfw + "-OUT"
    try:
        execute('ip6tables -L ' + brfwout)
    except:
        execute('ip6tables -N ' + brfwout)

    brfwin = brfw + "-IN"
    try:
        execute('ip6tables -L ' + brfwin)
    except:
        execute('ip6tables -N ' + brfwin)

    try:
        refs = int(execute("""iptables -n -L %s | awk '/%s(.*)references/ {gsub(/\(/, "") ;print $3}'""" % (brfw,brfw)).strip())
        refs6 = int(execute("""ip6tables -n -L %s | awk '/%s(.*)references/ {gsub(/\(/, "") ;print $3}'""" % (brfw,brfw)).strip())

        if refs == 0:
            execute("iptables -I FORWARD -i " + brname + " -j DROP")
            execute("iptables -I FORWARD -o " + brname + " -j DROP")
            execute("iptables -I FORWARD -i " + brname + " -m physdev --physdev-is-bridged -j " + brfw)
            execute("iptables -I FORWARD -o " + brname + " -m physdev --physdev-is-bridged -j " + brfw)
            phydev = execute("brctl show | awk '/^%s[ \t]/ {print $4}'" % brname ).strip()
            execute("iptables -A " + brfw + " -m state --state RELATED,ESTABLISHED -j ACCEPT")
            execute("iptables -A " + brfw + " -m physdev --physdev-is-bridged --physdev-is-in -j " + brfwin)
            execute("iptables -A " + brfw + " -m physdev --physdev-is-bridged --physdev-is-out -j " + brfwout)
            execute("iptables -A " + brfw + " -m physdev --physdev-is-bridged --physdev-out " + phydev + " -j ACCEPT")

        if refs6 == 0:
            execute('ip6tables -I FORWARD -i ' + brname + ' -j DROP')
            execute('ip6tables -I FORWARD -o ' + brname + ' -j DROP')
            execute('ip6tables -I FORWARD -i ' + brname + ' -m physdev --physdev-is-bridged -j ' + brfw)
            execute('ip6tables -I FORWARD -o ' + brname + ' -m physdev --physdev-is-bridged -j ' + brfw)
            phydev = execute("brctl show | awk '/^%s[ \t]/ {print $4}'" % brname ).strip()
            execute('ip6tables -A ' + brfw + ' -m state --state RELATED,ESTABLISHED -j ACCEPT')
            execute('ip6tables -A ' + brfw + ' -m physdev --physdev-is-bridged --physdev-is-in -j ' + brfwin)
            execute('ip6tables -A ' + brfw + ' -m physdev --physdev-is-bridged --physdev-is-out -j ' + brfwout)
            execute('ip6tables -A ' + brfw + ' -m physdev --physdev-is-bridged --physdev-out ' + phydev + ' -j ACCEPT')

        return True
    except:
        try:
            execute("iptables -F " + brfw)
            execute('ip6tables -F ' + brfw)
        except:
            return False
        return False


if __name__ == '__main__':
    logging.basicConfig(filename="/var/log/cloudstack/agent/security_group.log", format="%(asctime)s - %(message)s", level=logging.DEBUG)
    parser = OptionParser()
    parser.add_option("--vmname", dest="vmName")
    parser.add_option("--vmip", dest="vmIP")
    parser.add_option("--vmip6", dest="vmIP6")
    parser.add_option("--vmid", dest="vmID")
    parser.add_option("--vmmac", dest="vmMAC")
    parser.add_option("--vif", dest="vif")
    parser.add_option("--sig", dest="sig")
    parser.add_option("--seq", dest="seq")
    parser.add_option("--rules", dest="rules")
    parser.add_option("--brname", dest="brname")
    parser.add_option("--localbrname", dest="localbrname")
    parser.add_option("--dhcpSvr", dest="dhcpSvr")
    parser.add_option("--hostIp", dest="hostIp")
    parser.add_option("--hostMacAddr", dest="hostMacAddr")
    parser.add_option("--nicsecips", dest="nicSecIps")
    parser.add_option("--action", dest="action")
    (option, args) = parser.parse_args()
    if len(args) == 0:
        logging.debug("No command to execute")
        sys.exit(1)
    cmd = args[0]
    logging.debug("Executing command: " + str(cmd))

    for i in range(0, 30):
        if obtain_file_lock(lock_file) is False:
            logging.warning("Lock on %s is being held by other process. Waiting for release." % lock_file)
            time.sleep(0.5)
        else:
            break

    if cmd == "can_bridge_firewall":
        can_bridge_firewall(args[1])
    elif cmd == "default_network_rules":
        default_network_rules(option.vmName, option.vmID, option.vmIP, option.vmIP6, option.vmMAC, option.vif, option.brname, option.nicSecIps)
    elif cmd == "destroy_network_rules_for_vm":
        destroy_network_rules_for_vm(option.vmName, option.vif)
    elif cmd == "default_network_rules_systemvm":
        default_network_rules_systemvm(option.vmName, option.localbrname)
    elif cmd == "get_rule_logs_for_vms":
        get_rule_logs_for_vms()
    elif cmd == "add_network_rules":
        add_network_rules(option.vmName, option.vmID, option.vmIP, option.vmIP6, option.sig, option.seq, option.vmMAC, option.rules, option.vif, option.brname, option.nicSecIps)
    elif cmd == "network_rules_vmSecondaryIp":
        network_rules_vmSecondaryIp(option.vmName, option.nicSecIps, option.action)
    elif cmd == "cleanup_rules":
        cleanup_rules()
    elif cmd == "post_default_network_rules":
        post_default_network_rules(option.vmName, option.vmID, option.vmIP, option.vmMAC, option.vif, option.brname, option.dhcpSvr, option.hostIp, option.hostMacAddr)
    else:
        logging.debug("Unknown command: " + cmd)
        sys.exit(1)