Highlighting hex in listings

Question

I'm currently writing a document which has a large amount of output from Cisco routers. I would like to highlight the hexadecimal numbers such as MAC addresses which are within this, without highlighting every a-f character in the rest of the output.

I have tried using listings' literate option, which is working well for numerals, but I cannot get it to differentiate hex from any other text.

Below is my current number highlighting code:

      literate={%
          *{0}{{{\color{brown}0}}}1                   %
          {1}{{{\color{brown}1}}}1                    %
          {2}{{{\color{brown}2}}}1                    %
          {3}{{{\color{brown}3}}}1                    %
          {4}{{{\color{brown}4}}}1                    %
          {5}{{{\color{brown}5}}}1                    %
          {6}{{{\color{brown}6}}}1                    %
          {7}{{{\color{brown}7}}}1                    %
          {8}{{{\color{brown}8}}}1                    %
           {9}{{{\color{brown}9}}}1},              %

For good measure, here is my language declaration for the cisco commands, because I couldn't find one online:

\lstdefinelanguage{cisco}{
    keywords={Interface int, ip, no, end, line, login, router, network, version, hostname, shutdown, shut, sh, show},
    keywordstyle=\color{blue}\bfseries,
    ndkeywords={dhcp, pool, GigabitEthernet, g, address, addr, rip, console, con, aux, vty},
    ndkeywordstyle=\color{darkgray}\bfseries,
    identifierstyle=\color{black},
    sensitive=false,
    comment=[l]{!},
    commentstyle=\color{purple}\ttfamily,
    stringstyle=\color{red}\ttfamily,
}

Any help would be much appreciated.