Merge pull request #7 from p4lang/simple-nat

added simple_nat example

SIGCOMM_2015/source_routing/cleanup

@@ -1,2 +1 @@
-sudo killall simple_switch
-redis-cli FLUSHDB
+sudo killall lt-simple_switch

examples/README.md

@@ -15,6 +15,7 @@ included:
 - `counter`: how to use counters in P4
 - `action_profile`: how to use action profiles in P4, using ECMP as support
 - `resubmit`: how to resubmit packets to the ingress pipelines
+- `simple_nat`: a basic implementation of a full-cone NAT for TCP traffic
 
 All examples are orgranized the same way, with a `p4src` directory containing
 the P4 source code, and a `README` file describing the P4 program and explaining

examples/simple_nat/README.md

@@ -0,0 +1,62 @@
+# Simple NAT
+
+## Description
+
+This program implements a very basic full-cone NAT for TCP traffic (over
+IPv4). According to [Wikipedia]
+(https://en.wikipedia.org/wiki/Network_address_translation#Methods_of_translation),
+a full-cone NAT is defined as follows:
+
+Once an internal address (iAddr:iPort) is mapped to an external address
+(eAddr:ePort), any packets from iAddr:iPort are sent through eAddr:ePort. Any
+external host can send packets to iAddr:iPort by sending packets to eAddr:ePort.
+
+Note that this program was built on top of the simple_router P4 program, so you
+will find some similarities.
+
+This program was added to illustrate two things:
+- how to re-compute a TCP checksum after having modified the TCP header (which
+is required for a TCP NAT)
+- how to write a simple app that receives and emits "CPU packets"
+
+This program is slightly more advanced than most others in this repository, so
+we recommend that you become familiar with the copy_to_cpu example before
+studying this one.
+
+The program implements very basic funtionality only. For example it supports
+only one internal interface, even though we may extend this in the future. The
+Mininet topology used for the demo is the following:
+
+![Simple NAT topology](resources/topo.png)
+
+The program in a nutshell:
+- non-TCP traffic is dropped.
+- when a TCP packet is received on the external interface, for which there is no
+mapping, the packet is dropped.
+- when a TCP packet is received on the internal interface, for which there is no
+mapping, the packet is sent to CPU and 2 new rules are added to the `nat` table
+to allow translation and forwarding of TCP packets in both directions. The
+packet is then re-injected in the dataplane (to avoid dropping the SYN packet).
+- when a TCP packet is received on the either interface, for which there is a
+mapping, the appropriate rewrites are executed for the IPv4 and TCP headers and
+the packet is forwarded appropriately.
+
+The most important part of the program is the `nat` table. If you understand
+what this table is doing, the rest of the program is mostly IPv4 forwarding. You
+should also take a long look at [nat_app.py] (nat_app.py), which manages the
+mappings and dynamically adds rules to the `nat` table.
+
+We use 11 as the CPU port. There is a special CPU veth pair (`cpu-veth-0` /
+`cpu-veth-1`), which is use by the switch / the app to send and receive CPU
+packets. The veth pair is created by `run_demo.sh` and can be destroyed with
+`cleanup.sh`.
+
+### Running the demo
+
+To run the demo:
+- start the 1-switch Mininet topo with `sudo ./run_demo.sh`.
+- start the app with `sudo python nat_app.py`.
+- create a TCP flow in Mininet from `h1` (internal host) to `h2` (external host)
+  - `h2 iperf -s&`
+  - `h1 iperf -c h2`
+- you can cleanup the demo with `sudo ./cleanup.sh`

examples/simple_nat/cleanup.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+
+# Copyright 2013-present Barefoot Networks, Inc.
+#
+# Licensed 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.
+
+if [[ $EUID -ne 0 ]]; then
+    echo "This script should be run using sudo or as the root user"
+    exit 1
+fi
+
+killall lt-simple_switch &> /dev/null
+mn -c &> /dev/null
+intf="cpu-veth-0"
+if ip link show $intf &> /dev/null; then
+  ip link delete $intf type veth
+fi

examples/simple_nat/commands.txt

@@ -0,0 +1,17 @@
+table_set_default if_info _drop
+table_add if_info set_if_info 1 => 10.0.0.1 00:aa:bb:00:00:04 0
+table_add if_info set_if_info 2 => 192.168.0.1 00:aa:bb:00:00:05 1
+table_set_default nat _drop
+table_add nat nat_miss_ext_to_int 1 1 1 0.0.0.0&&&0.0.0.0 0.0.0.0&&&0.0.0.0 0&&&0 0&&&0 => 99
+table_add nat nat_miss_int_to_ext 0 1 1 0.0.0.0&&&0.0.0.0 0.0.0.0&&&0.0.0.0 0&&&0 0&&&0 => 99
+table_set_default ipv4_lpm _drop
+table_add ipv4_lpm set_nhop 10.0.0.10/32 => 10.0.0.10 1
+table_add ipv4_lpm set_nhop 192.168.0.10/32 => 192.168.0.10 2
+table_set_default forward _drop
+table_add forward set_dmac 10.0.0.10 => 00:04:00:00:00:10
+table_add forward set_dmac 192.168.0.10 => 00:05:00:00:00:10
+table_set_default send_frame _drop
+table_add send_frame do_rewrites 1 => 00:aa:bb:00:00:04
+table_add send_frame do_rewrites 2 => 00:aa:bb:00:00:05
+mirroring_add 250 11
+table_set_default send_to_cpu do_cpu_encap

examples/simple_nat/nat_app.py

@@ -0,0 +1,77 @@
+# Copyright 2013-present Barefoot Networks, Inc.
+#
+# Licensed 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.
+
+from scapy.all import *
+import subprocess
+import os
+
+CLI_PATH = None
+
+EXTERN_IP = "192.168.0.1"
+
+current_nat_port = 1025
+nat_mappings = {}
+
+def send_to_CLI(cmd):
+    this_dir = os.path.dirname(os.path.realpath(__file__))
+    p = Popen(os.path.join(this_dir, 'sswitch_CLI.sh'), stdout=PIPE, stdin=PIPE)
+    output = p.communicate(input=cmd)[0]
+    # print output
+
+# This is a very basic implementation of a full-cone NAT for TCP traffic
+# We do not maintain a state machine for each connection, so we are not able to
+# cleanup the port mappings, but this is sufficient for demonstration purposes
+def process_cpu_pkt(p):
+    global current_nat_port
+    global EXTERN_IP
+
+    p_str = str(p)
+    # 0-7  : preamble
+    # 8    : device
+    # 9    : reason
+    # 10   : iface
+    # 11-  : data packet (TCP)
+    if p_str[:8] != '\x00' * 8 or p_str[8] != '\x00' or p_str[9] != '\xab':
+        return
+    ip_hdr = None
+    tcp_hdr = None
+    try:
+        p2 = Ether(p_str[11:])
+        ip_hdr = p2['IP']
+        tcp_hdr = p2['TCP']
+    except:
+        return
+    print "Packet received"
+    print p2.summary()
+    if (ip_hdr.src, tcp_hdr.sport) not in nat_mappings:
+        ext_port = current_nat_port
+        current_nat_port += 1
+        print "Allocating external port", ext_port
+        nat_mappings[(ip_hdr.src, tcp_hdr.sport)] = ext_port
+        # internal to external rule for this mapping
+        send_to_CLI("table_add nat nat_hit_int_to_ext 0 1 1 %s&&&255.255.255.255 0.0.0.0&&&0.0.0.0 %d&&&0xffff 0&&&0 => %s %d 1" %\
+                    (ip_hdr.src, tcp_hdr.sport, EXTERN_IP, ext_port))
+        # external to internal rule for this mapping
+        send_to_CLI("table_add nat nat_hit_ext_to_int 1 1 1 0.0.0.0&&&0.0.0.0 %s&&&255.255.255.255 0&&&0 %d&&&0xffff => %s %d 1" %\
+                    (EXTERN_IP, ext_port, ip_hdr.src, tcp_hdr.sport))
+    # a little bit hacky, this essentially ensures that the packet we re-inject
+    # in the CPU iface will not be processed again by this method
+    new_p = p_str[:9] + '\xac' + p_str[10:]
+    sendp(new_p, iface="cpu-veth-0", verbose=0)
+
+def main():
+    sniff(iface="cpu-veth-0", prn=lambda x: process_cpu_pkt(x))
+
+if __name__ == '__main__':
+    main()

examples/simple_nat/p4src/simple_nat.p4

@@ -0,0 +1,364 @@
+/*
+Copyright 2013-present Barefoot Networks, Inc.
+
+Licensed 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.
+*/
+
+header_type ethernet_t {
+    fields {
+        dstAddr : 48;
+        srcAddr : 48;
+        etherType : 16;
+    }
+}
+
+header_type ipv4_t {
+    fields {
+        version : 4;
+        ihl : 4;
+        diffserv : 8;
+        totalLen : 16;
+        identification : 16;
+        flags : 3;
+        fragOffset : 13;
+        ttl : 8;
+        protocol : 8;
+        hdrChecksum : 16;
+        srcAddr : 32;
+        dstAddr: 32;
+    }
+}
+
+parser start {
+    set_metadata(meta.if_index, standard_metadata.ingress_port);
+    return select(current(0, 64)) {
+        0 : parse_cpu_header;  // dummy transition
+        default: parse_ethernet;
+    }
+}
+
+header_type cpu_header_t {
+    fields {
+        preamble: 64;
+        device: 8;
+        reason: 8;
+        if_index: 8;
+    }
+}
+
+header cpu_header_t cpu_header;
+
+parser parse_cpu_header {
+    extract(cpu_header);
+    set_metadata(meta.if_index, cpu_header.if_index);
+    return parse_ethernet;
+}
+
+#define ETHERTYPE_IPV4 0x0800
+
+header ethernet_t ethernet;
+
+parser parse_ethernet {
+    extract(ethernet);
+    return select(latest.etherType) {
+        ETHERTYPE_IPV4 : parse_ipv4;
+        default: ingress;
+    }
+}
+
+header ipv4_t ipv4;
+
+field_list ipv4_checksum_list {
+        ipv4.version;
+        ipv4.ihl;
+        ipv4.diffserv;
+        ipv4.totalLen;
+        ipv4.identification;
+        ipv4.flags;
+        ipv4.fragOffset;
+        ipv4.ttl;
+        ipv4.protocol;
+        ipv4.srcAddr;
+        ipv4.dstAddr;
+}
+
+field_list_calculation ipv4_checksum {
+    input {
+        ipv4_checksum_list;
+    }
+    algorithm : csum16;
+    output_width : 16;
+}
+
+calculated_field ipv4.hdrChecksum  {
+    verify ipv4_checksum;
+    update ipv4_checksum;
+}
+
+#define IP_PROT_TCP 0x06
+
+parser parse_ipv4 {
+    extract(ipv4);
+    set_metadata(meta.ipv4_sa, ipv4.srcAddr);
+    set_metadata(meta.ipv4_da, ipv4.dstAddr);
+    set_metadata(meta.tcpLength, ipv4.totalLen - 20);
+    return select(ipv4.protocol) {
+        IP_PROT_TCP : parse_tcp;
+        default : ingress;
+    }
+}
+
+header_type tcp_t {
+    fields {
+        srcPort : 16;
+        dstPort : 16;
+        seqNo : 32;
+        ackNo : 32;
+        dataOffset : 4;
+        res : 4;
+        flags : 8;
+        window : 16;
+        checksum : 16;
+        urgentPtr : 16;
+    }
+}
+
+header tcp_t tcp;
+
+parser parse_tcp {
+    extract(tcp);
+    set_metadata(meta.tcp_sp, tcp.srcPort);
+    set_metadata(meta.tcp_dp, tcp.dstPort);
+    return ingress;
+}
+
+field_list tcp_checksum_list {
+        ipv4.srcAddr;
+        ipv4.dstAddr;
+        8'0;
+        ipv4.protocol;
+        meta.tcpLength;
+        tcp.srcPort;
+        tcp.dstPort;
+        tcp.seqNo;
+        tcp.ackNo;
+        tcp.dataOffset;
+        tcp.res;
+        tcp.flags;
+        tcp.window;
+        tcp.urgentPtr;
+        payload;
+}
+
+field_list_calculation tcp_checksum {
+    input {
+        tcp_checksum_list;
+    }
+    algorithm : csum16;
+    output_width : 16;
+}
+
+calculated_field tcp.checksum {
+    verify tcp_checksum if(valid(tcp));
+    update tcp_checksum if(valid(tcp));
+}
+
+action _drop() {
+    drop();
+}
+
+header_type intrinsic_metadata_t {
+    fields {
+        mcast_grp : 4;
+        egress_rid : 4;
+        mcast_hash : 16;
+        lf_field_list: 32;
+    }
+}
+
+metadata intrinsic_metadata_t intrinsic_metadata;
+
+header_type meta_t {
+    fields {
+        do_forward : 1;
+        ipv4_sa : 32;
+        ipv4_da : 32;
+        tcp_sp : 16;
+        tcp_dp : 16;
+        nhop_ipv4 : 32;
+        if_ipv4_addr : 32;
+        if_mac_addr : 48;
+        is_ext_if : 1;
+        tcpLength : 16;
+        if_index : 8;
+    }
+}
+
+metadata meta_t meta;
+
+action set_if_info(ipv4_addr, mac_addr, is_ext) {
+    modify_field(meta.if_ipv4_addr, ipv4_addr);
+    modify_field(meta.if_mac_addr, mac_addr);
+    modify_field(meta.is_ext_if, is_ext);
+}
+
+table if_info {
+    reads {
+        meta.if_index : exact;
+    }
+    actions {
+        _drop;
+        set_if_info;
+    }
+}
+
+action nat_miss_ext_to_int() {
+    modify_field(meta.do_forward, 0);
+    drop();
+}
+
+#define CPU_MIRROR_SESSION_ID 250
+
+field_list copy_to_cpu_fields {
+    standard_metadata;
+}
+
+action nat_miss_int_to_ext() {
+    clone_ingress_pkt_to_egress(CPU_MIRROR_SESSION_ID, copy_to_cpu_fields);
+}
+
+action nat_hit_int_to_ext(srcAddr, srcPort) {
+    modify_field(meta.do_forward, 1);
+    modify_field(meta.ipv4_sa, srcAddr);
+    modify_field(meta.tcp_sp, srcPort);
+}
+
+action nat_hit_ext_to_int(dstAddr, dstPort) {
+    modify_field(meta.do_forward, 1);
+    modify_field(meta.ipv4_da, dstAddr);
+    modify_field(meta.tcp_dp, dstPort);
+}
+
+action nat_no_nat() {
+    modify_field(meta.do_forward, 1);
+}
+
+table nat      {
+    reads {
+        meta.is_ext_if : exact;
+        ipv4 : valid;
+        tcp : valid;
+        ipv4.srcAddr : ternary;
+        ipv4.dstAddr : ternary;
+        tcp.srcPort : ternary;
+        tcp.dstPort : ternary;
+    }
+    actions {
+        _drop;
+        nat_miss_int_to_ext;
+        nat_miss_ext_to_int;
+        nat_hit_int_to_ext;
+        nat_hit_ext_to_int;
+        nat_no_nat;  // for debugging
+    }
+    size : 128;
+}
+
+action set_nhop(nhop_ipv4, port) {
+    modify_field(meta.nhop_ipv4, nhop_ipv4);
+    modify_field(standard_metadata.egress_spec, port);
+    add_to_field(ipv4.ttl, -1);
+}
+
+table ipv4_lpm {
+    reads {
+        meta.ipv4_da : lpm;
+    }
+    actions {
+        set_nhop;
+        _drop;
+    }
+    size: 1024;
+}
+
+action set_dmac(dmac) {
+    modify_field(ethernet.dstAddr, dmac);
+}
+
+table forward {
+    reads {
+        meta.nhop_ipv4 : exact;
+    }
+    actions {
+        set_dmac;
+        _drop;
+    }
+    size: 512;
+}
+
+action do_rewrites(smac) {
+    // in case packet was injected by CPU
+    remove_header(cpu_header);
+    modify_field(ethernet.srcAddr, smac);
+    modify_field(ipv4.srcAddr, meta.ipv4_sa);
+    modify_field(ipv4.dstAddr, meta.ipv4_da);
+    modify_field(tcp.srcPort, meta.tcp_sp);
+    modify_field(tcp.dstPort, meta.tcp_dp);
+}
+
+table send_frame {
+    reads {
+        standard_metadata.egress_port: exact;
+    }
+    actions {
+        do_rewrites;
+        _drop;
+    }
+    size: 256;
+}
+
+action do_cpu_encap() {
+    add_header(cpu_header);
+    modify_field(cpu_header.preamble, 0);
+    modify_field(cpu_header.device, 0);
+    modify_field(cpu_header.reason, 0xab);  // does not mean anything
+    modify_field(cpu_header.if_index, meta.if_index);
+}
+
+table send_to_cpu {
+    actions { do_cpu_encap; }
+    size : 0;
+}
+
+control ingress {
+    // retrieve information on the ingress interface
+    apply(if_info);
+    // determine what to do with the packet and which rewrites to apply
+    // depending on direction (int -> ext or ext -> int) and existing nat rules
+    apply(nat);
+    // forward packet
+    if (meta.do_forward == 1 and ipv4.ttl > 0) {
+        apply(ipv4_lpm);
+        apply(forward);
+    }
+}
+
+control egress {
+    if (standard_metadata.instance_type == 0) {
+        // regular packet: execute rewrites
+        apply(send_frame);
+    } else {
+        // cpu packet: encap
+        apply(send_to_cpu);
+    }
+}

examples/simple_nat/resources/topo.graphml

@@ -0,0 +1,306 @@
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examples/simple_nat/run_demo.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+# Copyright 2013-present Barefoot Networks, Inc.
+#
+# Licensed 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.
+
+if [[ $EUID -ne 0 ]]; then
+    echo "This script should be run using sudo or as the root user"
+    exit 1
+fi
+
+THIS_DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+
+source $THIS_DIR/../env.sh
+
+P4C_BM_SCRIPT=$P4C_BM_PATH/p4c_bm/__main__.py
+
+SWITCH_PATH=$BMV2_PATH/targets/simple_switch/simple_switch
+
+CLI_PATH=$BMV2_PATH/targets/simple_switch/sswitch_CLI
+
+# create CPU port
+intf0="cpu-veth-0"
+intf1="cpu-veth-1"
+if ! ip link show $intf0 &> /dev/null; then
+    ip link add name $intf0 type veth peer name $intf1
+    ip link set dev $intf0 up
+    ip link set dev $intf1 up
+    TOE_OPTIONS="rx tx sg tso ufo gso gro lro rxvlan txvlan rxhash"
+    for TOE_OPTION in $TOE_OPTIONS; do
+        /sbin/ethtool --offload $intf0 "$TOE_OPTION" off
+        /sbin/ethtool --offload $intf1 "$TOE_OPTION" off
+    done
+fi
+sysctl net.ipv6.conf.$intf0.disable_ipv6=1
+sysctl net.ipv6.conf.$intf1.disable_ipv6=1
+
+$P4C_BM_SCRIPT p4src/simple_nat.p4 --json simple_nat.json
+PYTHONPATH=$PYTHONPATH:$BMV2_PATH/mininet/ python topo.py \
+    --behavioral-exe $BMV2_PATH/targets/simple_switch/simple_switch \
+    --json simple_nat.json \
+    --cli $CLI_PATH \
+    --thrift-port 22222

examples/simple_nat/sswitch_CLI.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+THIS_DIR=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
+
+source $THIS_DIR/../env.sh
+
+CLI_PATH=$BMV2_PATH/targets/simple_switch/sswitch_CLI
+
+$CLI_PATH simple_nat.json 22222

examples/simple_nat/topo.py

@@ -0,0 +1,113 @@
+#!/usr/bin/python
+
+# Copyright 2013-present Barefoot Networks, Inc.
+#
+# Licensed 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.
+
+from mininet.net import Mininet
+from mininet.topo import Topo
+from mininet.log import setLogLevel, info
+from mininet.cli import CLI
+from mininet.link import TCLink, Intf
+
+from p4_mininet import P4Switch, P4Host
+
+import argparse
+from time import sleep
+import os
+import subprocess
+
+parser = argparse.ArgumentParser(description='Mininet demo')
+parser.add_argument('--behavioral-exe', help='Path to behavioral executable',
+                    type=str, action="store", required=True)
+parser.add_argument('--json', help='Path to JSON config file',
+                    type=str, action="store", required=True)
+parser.add_argument('--cli', help='Path to BM CLI',
+                    type=str, action="store", required=True)
+parser.add_argument('--thrift-port', help='Thrift server port for table updates',
+                    type=int, action="store", required=True)
+
+args = parser.parse_args()
+
+class MyTopo(Topo):
+    def __init__(self, sw_path, json_path, thrift_port, **opts):
+        # Initialize topology and default options
+        Topo.__init__(self, **opts)
+
+        switch = self.addSwitch('s1',
+                                sw_path = sw_path,
+                                json_path = json_path,
+                                thrift_port = thrift_port,
+                                pcap_dump = True)
+
+        # internal host
+        h1 = self.addHost('h1',
+                          ip = "10.0.0.10",
+                          mac = "00:04:00:00:00:10")
+        self.addLink(h1, switch)
+
+        # external host
+        h2 = self.addHost('h2',
+                          ip = "192.168.0.10",
+                          mac = "00:05:00:00:00:10")
+        self.addLink(h2, switch)
+
+def main():
+    topo = MyTopo(args.behavioral_exe,
+                  args.json,
+                  args.thrift_port)
+
+    net = Mininet(topo = topo,
+                  host = P4Host,
+                  switch = P4Switch,
+                  controller = None)
+
+    cpu_intf = Intf("cpu-veth-1", net.get('s1'), 11)
+
+    net.start()
+
+    sw_macs = ["00:aa:bb:00:00:04", "00:aa:bb:00:00:05"]
+
+    sw_addrs = ["10.0.0.1", "192.168.0.1"]
+
+    for n in xrange(2):
+        h = net.get('h%d' % (n + 1))
+        h.setARP(sw_addrs[n], sw_macs[n])
+        h.setDefaultRoute("dev eth0 via %s" % sw_addrs[n])
+
+    for n in xrange(2):
+        h = net.get('h%d' % (n + 1))
+        h.describe()
+
+    sleep(1)
+
+    cmd = [args.cli, args.json, str(args.thrift_port)]
+    with open("commands.txt", "r") as f:
+        print " ".join(cmd)
+        try:
+            output = subprocess.check_output(cmd, stdin = f)
+            print output
+        except subprocess.CalledProcessError as e:
+            print e
+            print e.output
+
+    sleep(1)
+
+    print "Ready !"
+
+    CLI( net )
+    net.stop()
+
+if __name__ == '__main__':
+    setLogLevel( 'info' )
+    main()