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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="nsntrace" xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>nsntrace</title>
    <productname>nsntrace</productname>

    <authorgroup>
      <author>
        <firstname>Jonas</firstname>
        <surname>Danielsson</surname>
        <email>jonas@threetimestwo.org</email>
        <contrib>Original author</contrib>
      </author>
    </authorgroup>
  </refentryinfo>

  <refmeta>
    <refentrytitle>nsntrace</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>nsntrace</refname>
    <refpurpose>
      Perform a network trace of a process by using Linux network namespaces
    </refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>nsntrace</command>
      <arg choice="opt">options</arg>
      <arg choice="plain"><replaceable>program</replaceable></arg>
      <arg choice="opt">arguments</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>nsntrace</command> uses Linux network namespaces to
    perform network traces of the specified <replaceable>program</replaceable>.
    The traces are stored as pcap files. And can later be analyzed by
    applications such as <command>wireshark</command>.</para>

    <para><command>nsntrace</command> creates a new network namespace and
    launches the specified <replaceable>program</replaceable> in it. This
    will ensure that all the packets we trace come from the system or
    the specified <replaceable>program</replaceable>.</para>

    <para>To get around the isolation caused by the network namespace a
    virtual network interface is created. And in order for the
    <replaceable>program</replaceable> network traffic to reach the root
    network namespace <command>iptables</command> is used.</para>

    <para>Since <command>nsntrace</command> uses iptables and traces raw
    sockets it needs to be run as root.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following options are understood:</para>


    <variablelist>
      <varlistentry>
        <term><option>--device <replaceable>dev</replaceable></option></term>
        <term><option>-d <replaceable>dev</replaceable></option></term>

        <listitem><para>
          The network device to use in trace.
        </para></listitem>
      </varlistentry>


      <varlistentry>
        <term><option>--use-public-dns</option></term>
        <listitem><para>
          Override resolv.conf in namespace to use public nameservers from
          Quad9 (9.9.9.9), Cloudflare (1.1.1.1), Google (8.8.8.8) and
          OpenDNS (208.67.222.222).
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--outfile <replaceable>file</replaceable></option></term>
        <term><option>-o <replaceable>file</replaceable></option></term>

        <listitem><para>
          Write the trace output to the file <replaceable>file</replaceable>.
          Default is nsntrace.pcap. Use '-' for stdout.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--user <replaceable>user</replaceable></option></term>
        <term><option>-u <replaceable>user</replaceable></option></term>

        <listitem><para>
          Run program with the user ID, group ID and supplementary groups
          of <replaceable>user</replaceable>.
        </para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--filter <replaceable>filter</replaceable></option></term>
        <term><option>-f <replaceable>filter</replaceable></option></term>

        <listitem><para>
          The capture filter to use while capturing. See <citerefentry>
          <refentrytitle>pcap-filter</refentrytitle><manvolnum>7</manvolnum>
          </citerefentry> for <replaceable>filter</replaceable> syntax.
        </para></listitem>
      </varlistentry>

      </variablelist>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned; otherwise, a non-zero failure
    code is returned.</para>
  </refsect1>
</refentry>