diff --git a/config/main.tex b/config/main.tex
index 74e199d..8dfa539 100644
--- a/config/main.tex
+++ b/config/main.tex
@@ -1,6 +1,6 @@
 %# -*- coding: utf-8-unix -*-
 
-%============================================================
+%============================================================================
 % 基本库
 \usepackage{longtable}
 \usepackage{multirow}
@@ -15,8 +15,8 @@
             linkcolor=purple,citecolor=red,plainpages=false]{hyperref}
 \usepackage[centering,a4paper,body={16cm,22cm}]{geometry}
 
-% %============================================================
-% % 配制全局字体
+%============================================================================
+% 配制全局字体
 % \setmonofont{inconsolata}  % 使用 inconsolata 等宽字体
 
 % % 使用方正系列字体
@@ -33,19 +33,19 @@
 % \renewcommand*{\fangsong}{\CJKfamily{zhfs}}     % 仿宋
 % \renewcommand*{\lishu}{\CJKfamily{zhli}}        % 隶书
 
-%============================================================
+%============================================================================
 % 配制列表环境
 \usepackage{enumitem}
 \setlist{nosep}  % 紧凑间距
 \setlist*{leftmargin=*}  % 列表和段落头对齐
 \setlist[1]{labelindent=\parindent} % Only the level 1
-%============================================================
+%============================================================================
 % 绘图支持
 \usepackage{tikz}
 \definecolor{c1}{RGB}{116, 52, 129} %清华紫
 \definecolor{c2}{RGB}{130, 80, 140}
 \definecolor{c3}{RGB}{230, 180, 240}
-%============================================================
+%============================================================================
 % 定制代码框
 \usepackage[breakable,minted]{tcolorbox}
 \newtcblisting{code}[1][]{
@@ -67,30 +67,30 @@
     mathescape
   }
  }
-%============================================================
+%============================================================================
 % 设置 PDF 文件信息
 \hypersetup{
   pdfauthor = {计算机网络教案社区},
   pdftitle = {实验指导书},
   pdfkeywords = {计算机网络}}
 
-%============================================================
+%============================================================================
 % 文档风格
 \ctexset{today=small}
 \ctexset{contentsname=目~~~~录}
 \setcounter{secnumdepth}{4}  % 章节编号深度 (part 对应 -1)
 \setcounter{tocdepth}{1}     % 目录深度 (part 对应 -1)
-%============================================================
+%============================================================================
 % 每节单独起一页
 \newcommand{\sectionbreak}{\clearpage}
-%============================================================
+%============================================================================
 % 居中章节标题
 \newenvironment{pre}{
   \titleformat{\chapter}[display]{\centering}{}{-3mm}{\Huge\heiti}
   \titlespacing{\chapter}{0pt}{0pt}{2\baselineskip}
   \chapter{前~~~~言}{}
 }{}
-%============================================================
+%============================================================================
 % chapter级样式设置
 \ctexset{chapter/name = {第,单元}}
 \titleformat{\chapter}[display]{\flushleft}{
@@ -102,7 +102,7 @@
   \end{tikzpicture}
 }{-30mm}{\Huge\heiti}
 \titlespacing{\chapter}{0pt}{0pt}{2\baselineskip}
-%============================================================
+%============================================================================
 % section级样式设置
 \ctexset{section/break = \Needspace{\textheight}}
 \ctexset{section={
@@ -111,7 +111,7 @@
   afterskip={1.0ex \@plus .2ex},
   }
 }
-%============================================================
+%============================================================================
 % subection级样式设置
 \ctexset{subsection={
   format={\bfseries\heiti\normalsize},
@@ -120,7 +120,7 @@
   number={\chinese{subsection}~.}
   }
 }
-%============================================================
+%============================================================================
 % subsubection级样式设置
 \ctexset{subsubsection={
   format={\bfseries\bfseries\normalsize},
@@ -129,7 +129,7 @@
   number={\arabic{subsection}.\arabic{subsubsection}}
   }
 }
-%============================================================
+%============================================================================
 % paragraph级样式设置
 \ctexset{paragraph={
   format={\normalfont\normalsize},
@@ -137,7 +137,7 @@
   number={\arabic{subsection}.\arabic{subsubsection}.\arabic{paragraph}}
   }
 }
-%============================================================
+%============================================================================
 % 设置页眉与页脚样式
 \def\markboxwidth{0.75\textwidth}
 \pagestyle{fancy}
@@ -152,20 +152,20 @@
 \addtolength{\headheight}{2.5pt}
 \renewcommand{\footrulewidth}{0pt}
 \fancypagestyle{plain}{\fancyhead{}\renewcommand{\headrulewidth}{0pt}}
-%============================================================
+%============================================================================
 % 设置图片的标题样式
 \DeclareCaptionFont{heiti}{\heiti}
 \captionsetup{format=plain,labelformat=simple,
               labelsep=space,justification=centering,
               font={small,heiti}}
 \captionsetup[sub]{font=footnotesize}
-%======================================================================
+%============================================================================
 % 设置图、表的号
 \numberwithin{figure}{section}
 \numberwithin{table}{section}
 \renewcommand{\thefigure}{\arabic{chapter}.\arabic{section}--\arabic{figure}}
 \renewcommand{\thetable}{\arabic{chapter}.\arabic{section}--\arabic{table}}
-%======================================================================
+%============================================================================
 % 设置目录格式
 \makeatletter
 \renewcommand\tableofcontents{%
@@ -177,11 +177,11 @@
 }
 \addtocontents{toc}{\let\string\CTEX@spaceChar\relax}
 \makeatother
-%======================================================================
+%============================================================================
 % 行距缩放
 \linespread{1.5}
 \renewcommand{\arraystretch}{1}
-%======================================================================
+%============================================================================
 % 调整附录格式
 \let\stdappendix\appendix
 \renewcommand{\appendix}{
diff --git a/data/ch_wireshark/sec_tcp.tex b/data/ch_wireshark/sec_tcp.tex
index 22c1b8a..cf5b75b 100644
--- a/data/ch_wireshark/sec_tcp.tex
+++ b/data/ch_wireshark/sec_tcp.tex
@@ -53,29 +53,8 @@ TCP 报文段结构如图\ref{fig:c:wireshark_TCP-structure}所示，
 \small
 \begin{figure}[!ht]
   \centering
-  \begin{code}[text]
-    0                   1                   2                   3
-    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |          Source Port          |       Destination Port        |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                        Sequence Number                        |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                    Acknowledgment Number                      |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |  Data |           |U|A|P|R|S|F|                               |
-    | Offset| Reserved  |R|C|S|S|Y|I|            Window             |
-    |       |           |G|K|H|T|N|N|                               |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |           Checksum            |         Urgent Pointer        |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                    Options                    |    Padding    |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    |                             data                              |
-    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-  \end{code}
-% \includegraphics[width=10cm]{TCP-structure}
-  \caption{TCP报文段结构标意图}
+  \includegraphics[width=10cm]{TCP-structure}
+  \caption{TCP报文段结构示意图}
   \label{fig:c:wireshark_TCP-structure}
 \end{figure}
 
diff --git a/figure/chapters/wireshark/TCP-status-machine.pdf b/figure/chapters/wireshark/TCP-status-machine.pdf
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diff --git a/figure/chapters/wireshark/TCP-status-machine.png b/figure/chapters/wireshark/TCP-status-machine.png
deleted file mode 100644
index 43e21ef..0000000
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diff --git a/figure/chapters/wireshark/TCP-structure.pdf b/figure/chapters/wireshark/TCP-structure.pdf
new file mode 100644
index 0000000..ea94989
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diff --git a/figure/chapters/wireshark/TCP-structure.png b/figure/chapters/wireshark/TCP-structure.png
deleted file mode 100644
index 6950d81..0000000
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diff --git a/figure/chapters/wireshark/TCP-time-line.pdf b/figure/chapters/wireshark/TCP-time-line.pdf
new file mode 100644
index 0000000..54270a9
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diff --git a/figure/chapters/wireshark/TCP-time-line.png b/figure/chapters/wireshark/TCP-time-line.png
deleted file mode 100644
index 12af25c..0000000
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diff --git a/figure/chapters/wireshark/TCP-topo.pdf b/figure/chapters/wireshark/TCP-topo.pdf
new file mode 100644
index 0000000..c8b84e5
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diff --git a/figure/chapters/wireshark/TCP-topo.png b/figure/chapters/wireshark/TCP-topo.png
deleted file mode 100644
index d34e1aa..0000000
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diff --git a/figure/chapters/wireshark/icmp-structure.pdf b/figure/chapters/wireshark/icmp-structure.pdf
new file mode 100644
index 0000000..b6b50d8
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diff --git a/figure/chapters/wireshark/icmp-structure.png b/figure/chapters/wireshark/icmp-structure.png
deleted file mode 100644
index d95ea87..0000000
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diff --git a/figure/chapters/wireshark/ip-structure.pdf b/figure/chapters/wireshark/ip-structure.pdf
new file mode 100644
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