% $Cambridge: hermes/doc/talks/2008-10-techlinks/talk.tex,v 1.1 2009/07/20 17:33:32 fanf2 Exp $

% This file is included by notes.tex and slides.tex

\usepackage[english,british]{babel}
\usepackage{pgf,pgfarrows,pgfshade}
\usepackage{calc} % for frame column width calculations
\usepackage{ulem} % for strikeout
\usepackage{url}

\newcommand\image[2][]{\mode<beamer>{\includegraphics[#1]{#2}}}

\newcommand\notes[1]{\mode<article>{#1}}

% args: title, body
\newcommand\slide[2]{
  \frame{\frametitle{#1}#2}
}

% args: (optional) image width, image name, title, body
\newcommand\slideT[4][10cm]{
  \slide{#3}{
    \centering\image[width=#1]{#2}

    #4
  }
}
\newcommand\slideB[4][10cm]{
  \slide{#3}{
    #4

    \centering\image[width=#1]{#2}
  }
}
\newcommand\slideBL[4][10cm]{
  \slide{#3}{
    #4

    \raggedright\image[width=#1]{#2}
  }
}
\newcommand\slideBR[4][10cm]{
  \slide{#3}{
    #4

    \raggedleft\image[width=#1]{#2}
  }
}
\newcommand\slideL[4][5cm]{
  \slide{#3}{
    \begin{columns}
    \column{#1}
      \image[width=#1]{#2}
    \column{10cm - #1}
      #4
    \end{columns}
  }
}
\newcommand\slideR[4][5cm]{
  \slide{#3}{
    \begin{columns}
    \column{10cm - #1}
      #4
    \column{#1}
      \image[width=#1]{#2}
    \end{columns}
  }
}

\DeclareUrlCommand\email{%
  \def\UrlLeft{<}%
  \def\UrlRight{>}%
  \urlstyle{tt}%
}

% first slide

\author[Tony~Finch]{
  Tony~Finch\\
  \email{fanf2@cam.ac.uk}
  \email{dot@dotat.at}
}

\institute[Cambridge UCS]{%
  University of Cambridge\\
  Computing Service\\
  Mail Support%
}

\titlegraphic{%
  \raisebox{1pt}{%
    \includegraphics[height=20pt]{univ.jpg}%
  }%
  \hspace{6pt}%
  \includegraphics[height=22pt]{ucs.jpg}%
}

% title page

\title{
  Techlinks email update
}
\subtitle{
  \url{http://www-uxsup.csx.cam.ac.uk/~fanf2/}
}
\date{Wednesday 29 October 2008}

\begin{document}

\frame{\maketitle}

\notes{
  \begin{abstract}
    This talk covers recent changes to the Computing Service's email
    services, including quota changes, webmail changes, and especially
    anti-spam changes.
  \end{abstract}
}

% down to business

\section{Hermes}

\slideT[4cm]{hermes.jpg}
  {Hermes update}{}

\subsection{Quotas}

\slideT[6cm]{parcel-big.jpg}
  {Standard Hermes quota}
{
  \mode<beamer>{\vspace{24pt}}
  \sout{1 GB}

}
\notes{
  In my previous talk 6 months ago, I announced that we had increased
  the standard Hermes quota to 1GB.
}

\slideT[6cm]{parcel-small.jpg}
  {Standard Hermes quota}
{
  \mode<beamer>{\vspace{24pt}}
  500 MB

}
\notes{
  Unfortunately we had to reduce it again. The increase was based on
  the assumption that we would replace some old hardware over the
  summer, and that the new hardware would provide more space.
}

\slideL{creditcrunch.jpg}
  {Budget problems}
{
  Still waiting for confirmation
  of this year's hardware budget...
}
\notes{
  Last year's money disappeared before we could spend it. We hope that
  we will get some money this year, otherwise further austerity
  measures will be imposed.
}

\slideR[4cm]{ration.jpg}
  {Quota increases}
{
  \begin{itemize}
  \item
    Quota upgrades still available
  \item
    \url{http://www.cam.ac.uk/cs/request/quota.html}
  \item
    Good reason required!
  \end{itemize}
}
\notes{
  The previous regime was fairly laissez faire about quota increases.
  We're now being rather stricter about the reasonableness of quota
  requests, especially for students - though less so for staff.
}

\subsection{Redstone}

\slideL[4cm]{redstone-launch.jpg}
  {Redstone}
{
  \image[width=4cm]{redstone.png}
  \begin{itemize}
  \item
    Hermes now split half and half
  \item
    Computing Service (city centre)
  \item
    Redstone (north Cambridge)
  \item
    Continuous replication

    from live half to backup half
  \item
    Manual fail-over
  \end{itemize}
}
\notes{
  This means our disaster recovery plan does not inevitably require a
  week to restore stale data from tape. We don't yet know if this will
  improve availability. A lot of the network still depends on the
  Computing Service machine room, especially our link to the outside
  world.

  The nuclear weapon illustrating the slide is a ``Redstone''
  medium-range ballistic missile.
}

\subsection{Webmail}

\slideT[6cm]{web.jpg}
  {Webmail}{}
\notes{
  A few comments about Hermes webmail.
}

\slideT[9.75cm]{webmail-old.png}
  {Old webmail style}{}
\slideT[9.75cm]{webmail-new.png}
  {New webmail style}{}
\notes{
  We have reskinned webmail according to the new University house style.
}

\slideT[9.75cm]{webmail-front.png}
  {New webmail front page}{}
\notes{
  The webmail front page provides quick links to UCS news items.
}

\slideT[9.75cm]{webmail-survey.png}
  {Webmail survey}{}
\notes{
  We received a lot of feedback in the first week after introducing
  the new look webmail. We're now running a survey to encourage more
  feedback. It'll continue until the end of term.
}

\slideB[6cm]{kerberos.png}
  {Log in via Raven}
{
  \centering
  Starting Monday 17th November
  \mode<beamer>{\vspace{24pt}}
}
\notes{
  Webmail will support the University's web single sign-on service for
  login. This was announced in September.

  I used a cartoon featuring Kerberos (Cerberus) to illustrate this
  even though Raven isn't based on the Kerberos single sign-on protocol.
}

\section{Anti-spam}

\slideT{spamalot.jpg}
  {Anti-spam upgrade}
{}
\notes{
  Now I'm going to talk a bit about the upgrade to the spam and virus
  filters that we did over the summer, five years after the last big upgrade.
}

\subsection{Overview}

\slideBR[5cm]{bounce.jpg}
  {Constraints on late scanning}
{
  \begin{itemize}
  \item
    We must not emit autoreplies
    \begin{itemize}
    \item
      spam and viruses have bogus sender addresses.
    \end{itemize}
  \item
    So our options are:
    \begin{itemize}
    \item
      deliver the message (perhaps after modification)
    \item
      quarantine it
    \item
      throw it away
    \end{itemize}
  \end{itemize}
}
\notes{
  The old scanner scanned email after we accepted responsibility for
  delivering it, which put some constraints on what the software could
  do when it found a dodgy message. The most important one is that we
  mustn't cause backscatter by emitting messages in response to spam
  or viruses.
}

\slideR[3.5cm]{crazy-frog.jpg}
  {Annoying things}
{
 \begin{itemize}
 \item
   Stripped attachments are awkward
 \item
   Risky phish handling
 \item
   Complaints about forwarded spam
 \item
   Quantity of stored spam
 \end{itemize}
}
\notes{
  This led to some annoying consequences, which were the motivation
  for the upgrade.

  I'll discuss these in more detail in a moment.
}

\slideBR[5cm]{no-soliciting.jpg}
  {Scanning early}
{
 \begin{itemize}
 \item
   Reject messages as soon as possible
 \item
   doesn't cause backscatter
 \item
   legitimate email doesn't disappear
 \item
   performance is more important
 \end{itemize}
}
\notes{
  There's a point in the SMTP protocol after the message data has been
  transmitted, and before the receiving MTA confirms to the sending
  MTA that it has received the message OK. The receiver can scan the
  message at this point and reject it if it looks bad.

  This usually causes spam and viruses to disappear, because spamming
  software does nothing when its messages are rejected. Legitimate
  senders, on the other hand, will inform the message's author of the
  problem using a bounce message. In this case the sending MTA usually
  knows the author is correct so the bounce will not be backscatter.

  The disadvantage is that there's relatively little time in which to
  do the scan. If load gets too high the recipient can't delay
  scanning until capacity is available.
}

\subsection{Problems and improvements}

\slideT[5cm]{mangle.jpg}
  {Stripped attachments}{}
\notes{
  If a legitimate message had an attachment with a ``dangerous''
  filename, then it was stripped and delivered to the recipient.
  This required some back-and-forth to resolve because the sender was
  not directly informed of the problem.

  When we scan early, the sender gets immediate nofication of a
  problem, and can correct it without wasting the recipient's time.
}

\slideT[5cm]{fishing.jpg}
  {Phishing risks}{}
\notes{
  We decided, because of the volume of phishing email, to treat it
  like mass-mailing viruses and just discard it. This was less safe
  than is ideal, because heuristic phishing detection is not as
  accurate as anti-virus signature matching.

  A recent example was an email from Barclays that contained a link
  allegedly to \url{www.stockbrokers.barclays.co.uk} but which
  actually went to \url{www.barclayswealth.com}, just like a phishing
  attack.

  Because early rejection generally does the right thing, false
  positives caused by this kind of foolishness are not such a
  disaster, so we can use more aggressive scanners which have much
  better coverage but a slightly higher false positive rate.
}

\slideT[5cm]{disappear.jpg}
  {Other virus risks}{}
\notes{
  If the old scanner detected a non-mass-mailing virus it stripped the
  attachment rather than discarding the message, in case it was
  something like a macro virus attached to a legitimate message.

  We can now treat all viruses the same.
}

\slideT[6cm]{pass-the-parcel.jpg}
  {Forwarded spam}{}
\notes{
  About 90\% of email is spam, and about 90\% of spam is blocked by
  DNS blacklists. This means the email that gets past this first
  hurdle is about half-and-half spam and legitimate.

  We dealt with spam by tagging and delivering it, expecting the
  recipient to filter it. This is not good for our email servers'
  reputation if the recipient forwards their email offsite, and the
  destination site observes a large proportion of spam in email from
  the University.

  We now reject spam that scores more than 10. This eliminates about
  $2/3$ of spam, which substantially reduces this problem.
}

\slideT[5cm]{flooded-car.jpg}
  {Size of spam folders}{}
\notes{
  An advantage of delivering spam to a different folder is that if a
  legitimate message is mis-classified, the recipient can retrieve it
  without the sender having to jump through awkward hoops. However
  people are very inaccurate at finding legitimate email in a pile of
  spam, and usually don't bother looking unless an expected message
  hasn't arrived in their inbox.

  We also had to implement automatic pruning of old messages in users'
  spam folders, to prevent them from using all the available disk space.

  The new setup's blocking threshold of 10 is quite conservative,
  so the advantage of being able to recover mis-classified messages is
  preserved. The smaller quantity of delivered spam should make this
  less of a chore.
}

\subsection{Other changes}

\slideB[7cm]{police.jpg}
  {Policy variations}
{}
\notes{
  The filtering policy we apply to email differs for internal and
  external email.
}

\slideR{door-inside.jpg}
  {Internal email}
{
 \begin{itemize}
 \item
   Anti-virus only
 \end{itemize}
}
\notes{
}

\slideL{door-outside.jpg}
  {External email}
{
 \begin{itemize}
 \item
   Anti-virus
 \item
   Anti-spam
 \end{itemize}
}
\notes{
}

\slideBR[5cm]{miner.jpg}
  {Minor changes}
{
 \begin{itemize}
 \item
   More informative spam details header
 \item
   Faster delivery, especially for internal email
 \end{itemize}
}
\notes{
  Faster delivery because the scanner is no longer batch-based, and
  because internal email doesn't have to wait for the spam scanner to
  process external email.
}

\subsection{Last few words}

\slideL{obama.jpg}
  {Future}
{
  \begin{itemize}
  \item
    Greylisting
  \item
    Adaptive scoring
  \end{itemize}
}
\notes{
  At the moment I'm working on a greylisting implementation. The aim
  is to delay suspicious email to allow time for 3rd party spam and
  virus filters to update. If it is successful, then new threats will
  be old enough that they are detected by the time we see them.

  After that, a system for users to provide feedback to the filters,
  e.g. marking undetected messages as spam so that the filters can
  detect them in the future.
}

\slideT[6cm]{the-end.jpg}
  {}
{
  \mode<beamer>{\vspace{24pt}}
  \centering\texttt{221 closing connection}

}

\end{document}

% eof
