設定 Wireshark 解析無法被預設設定解析出來的封包

有時候我們改變 RFC 定義預設的 port number，Wireshark 就無法解析用預設的設定解析出封包。這時候我們可以在該封包上點滑鼠右鍵，選 Decode as，指定我們想要的 Protocol 解析方式，就可以看到原來 Protocol 應該顯示的欄位。

http://www.wireshark.org/docs/wsug_html_chunked/ChCustProtocolDissectionSection.html#ChAdvDecodeAsFig

SNMPv3 engine-id discovery

節錄自 RFC3414

4. Discovery
   The User-based Security Model requires that a discovery process
   obtains sufficient information about other SNMP engines in order to
   communicate with them.  Discovery requires an non-authoritative SNMP
   engine to learn the authoritative SNMP engine’s snmpEngineID value
   before communication may proceed.  This may be accomplished by
   generating a Request message with a securityLevel of noAuthNoPriv, a
   msgUserName of zero-length, a msgAuthoritativeEngineID value of zero
   length, and the varBindList left empty.  The response to this message
   will be a Report message containing the snmpEngineID of the
   authoritative SNMP engine as the value of the
   msgAuthoritativeEngineID field within the msgSecurityParameters field.  It contains a Report PDU with the usmStatsUnknownEngineIDs
   counter in the varBindList.
   If authenticated communication is required, then the discovery
   process should also establish time synchronization with the
   authoritative SNMP engine.  This may be accomplished by sending an
   authenticated Request message with the value of
   msgAuthoritativeEngineID set to the newly learned snmpEngineID and
   with the values of msgAuthoritativeEngineBoots and
   msgAuthoritativeEngineTime set to zero.  For an authenticated Request
   message, a valid userName must be used in the msgUserName field.  The
   response to this authenticated message will be a Report message
   containing the up to date values of the authoritative SNMP engine’s
   snmpEngineBoots and snmpEngineTime as the value of the
   msgAuthoritativeEngineBoots and msgAuthoritativeEngineTime fields
   respectively.  It also contains the usmStatsNotInTimeWindows counter
   in the varBindList of the Report PDU.  The time synchronization then
   happens automatically as part of the procedures in section 3.2 step
   7b.  See also section 2.3.

Google Reader 快捷鍵

j/k	item down/up	selects the next/previous item in the list
space/shift-space	page down/up	moves the page down/up
n/p	scan down/up	in list view, selects the next item without opening it
o	open/close item	in list view, expands or collapses the selected item
enter	open/close item	in list view, expands or collapses the selected item
s	toggle star	stars the selected item
shift+s	toggle share	shares the selected item
m	mark as read/unread	switches the read state of the selected item
t	tag an item	opens the tagging field for the selected item
v	view original	opens the original source for this article in a new window
shift+a	mark all as read	marks all items in the current view as read
1	expanded view	displays the subscription as expanded items
2	list view	displays the subscription as a list of headlines
r	refresh	refreshes the unread counts in the navigation
shift+n/p	navigation down/up	selects the next/previous subscription or folder in the navigation
shift+x	navigation expand/collapse	expand or collapse a folder selected in the navigation
shift+o	navigation open subscription	opens the item currently selected in the navigation
g+h	go to home	goes to the Google Reader homepage
g+a	go to all items	goes to the "All items" view
g+s	go to starred items	goes to the "Starred items" view
g+t	go to tag	allows you to navigate to a tag by entering the tag name
g+u	go to subscription	allows you to navigate to a subscription by entering the subscription name
u	toggle full screen mode	hides and shows the list of subscriptions
?	keyboard shortcuts help	displays a quick guide to all of Reader's shortcuts

From 華為 RD

看見了If，就想Else。

看見malloc，就去找Free。

函式呼叫要小心，需要看看返回值。

看到for迴圈，就找邊界值。

看見return要注意，要去前面找資源。

看見陣列把神提，問題往往在下標。

不要小看字串，長度是個大問題。

得到函數不要急，看看變數初始化，各種路徑要小心。

賦值函數最危險，變數沒有初始化。

九句句真言不孤立，相互結合顯神威

所有的問題只在於你有沒有毅力

在某個 RD 的簽名檔上看到的

"所有的問題只在於你有沒有毅力"

構圖技巧筆記

1. 三分法：將拍攝範圍用直線和橫線分為三等分，拍攝主體盡量安置在直線和橫線的交點上 (共有四個焦點)，避免畫面過於四平八穩、單調。

2. 拍攝範圍中的水平線務必要保持水平。可用相機的水平儀、LCD螢幕的邊線、或是三分法的輔助線來協助對齊。

3. 妥善分配畫面中各項元素的比例，如拍攝主體、前景、背景，不要喧賓奪主，也不要頭重腳輕。

4. 前景、背景不要雜亂。

5. 人的視線會順著畫面中的線條延伸，坐落在點上 (轉折、交會處)，注意點安置的位置 (如利用三分法)。

6. 讓主體填滿畫面。

7. 避免幾何失真 (如利用廣角端近拍，造成畫面被擠壓)。




PS. 持續增加中...

對焦技巧筆記

1. 在構圖時若發現被攝物主體不在相機預設的對焦範圍中時，先將被攝物置於對焦範圍中半按快門對被攝物對焦，將相機可視範圍移回原先構圖後，直接按下快門到底拍攝。

持續累積中.....