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Where can I learn more about the company and its products?
The Netscape's Home page (choose Directory|Netscape's Home) can direct you to most of the content pages produced by the company. You'll find links for escapes on the Internet, company and product information, a Netscape merchandise store, news and reference, assistance, and a community center. This is the place to go for up-to-date information on Netscape software as well as contacts to sites around the world.
Several items in the Help menu provide specific information:
What is the World Wide Web's place in the Internet?
World Wide Web (WWW or Web) is one facet of the Internet consisting of client and server computers handling multimedia documents. Client computers use browser software (such as Netscape Navigator) to view documents (pages). Server computers use server software to maintain documents for clients to access.
Web documents are created by authors using a language called HTML (HyperText Markup Language) that offers short codes (also called tags) to designate graphical elements and links. Clicking on links brings documents located on a server to a browser, irrespective of the server's geographic location. Documents may contain text, images, sounds, movies, or a combination.
Documents are addressed with a URL (Uniform Resource Locator or, for short, location). Clients and servers use a document's URL to find and distinguish among documents.
What does each part of an Internet address mean?
Here's the components of the Internet address aname@aserver.com:
The three-letter suffix in the location name helps identify the kind of organization operating the server. (Some locations use a two-letter geographical suffix.) Here are the common suffixes and organizational affiliation:
What's the purpose of server push and client pull?
Generally, pages are brought to your screen as a result of your input. You click on a link or an image to request a page. But servers also have the ability to automatically deliver an updated version of a page to your screen. For example, a weather watcher might want to see an updated satellite photo at 15-minute intervals. Netscape provides the pages creators and server administrators two complementary tools for making this work.
In server push, a HTTP connection is held open for an indefinite period of time (until the server is finished sending data to the client or until the client interrupts the connection). In client pull, a HTTP connection is never held open; rather, the client is told when to open a new connection and what data to fetch. Server push uses a variant of the MIME message format "multipart/mixed" that lets a single message (or HTTP response) contain many data items. Client pull uses an HTTP response header (or equivalent HTML tag) that tells the client what to do after a specified time delay.
How do I learn to write HTML and publish pages?
You can write HTML (HyperText Markup Language) pages using any word processor or text editor. To publish pages on the Internet, you need to submit your pages to a server (a networked computer running server software). HTML uses embedded codes (tags) to designate graphical elements and links. These codes can be produced simply from your keyboard using angled brackets and the slash character. For example, the tag <B> presents text in bold letters. An HTML source file containing the expression <B>This stands out.</B> is displayed on screen in bold. Notice that the tag </B> is required to notate the end of the bold expression.
HTML consists of many such tags, including tags for big headlines, underlining, italics, titles, paragraph breaks, images, and links. Choose the Help|How to Create Web Services menu item for links to online HTML tutorials (or find an HTML guidebook in a bookstore). Netscape also supports tags that allow you to create frames, tables, custom backgrounds, and JavaScript programming code. Consult Netscape's online pages to learn how to take advantage of these features. Consult Netscape's online pages to learn how to take advantage of these features.
One feature you'll certainly want to use is the HTML link. Here's an example of HTML that creates a link for users to click on:
<A HREF="http://home.netscape.com/index.html">Home</A>
The section between quotes is the page's URL you'll see when you click on the link. The text following the URL contains the highlighted text (Home) the user sees on screen. The tag coding and brackets are also a required part of the link.
The method to insert images in your pages in very similar to that of inserting links. Inline images are links to image files. To see any one page's HTML source, you can choose the View|Document Source menu item. This command displays the text and tags used to create the content and content style of the current page.
Before you can use news for the first time you need to configure Netscape to point to your Usenet news server. Set the host name of your news (NNTP) server in the Mail and News|Servers panel. Your newsgroup subscription information is stored in a News file. If you have no previous News file, Netscape creates one that lists a couple of newsgroups designed for new users.
By default, news messages are displayed in a threaded format. The threaded format groups all messages that are related to each other in a compact, ordered listing. Messages that are responses to previous messages are nested under the parent messages.
Newsgroup pane: shows a listing of the news servers and Usenet groups currently available. Click on a newsgroup to display its messages in the message heading pane.
Settings in the Options menu let you change the newsgroups you see in the pane. You can subscribe to newsgroups by first showing all newsgroups, then clicking a particular newsgroup's Subscribe icon (a check mark) in the pane. After subscribing to newsgroups you want, you can change the Options menu setting so that you view only subscribed newsgroups. (An active newsgroup is a subscribed newsgroup with unread messages.) Other columns in the newsgroup pane tell you the number of unread messages and the total number of messages per newsgroup.
The leftmost folders in the newsgroup pane show the news servers (news hosts) you've connected to. You'll have only one folder here if you've connected to the default news server only. You'll have more than one folder if you've connected to multiple news servers.
Message heading pane: shows a list of a selected newsgroup's messages. Click on a message heading to display its content in the message pane.
Message content pane: shows a single message. The message can contain links to other messages or Internet pages.
Use the toolbar or menu items to display the Message Composition window for replying to a message or posting a new message. You can also use the Message Composition window to reply by email to the message sender.
How do you create cascading (hierarchical) bookmark menus?
How do you convert hotlists to bookmarks?
Other browsers use hotlists similar to the way that Netscape uses bookmarks. Users of other browsers might want to preserve the URLs they have accumulated as hotlists by converting them to bookmarks.
Choose the Window|Bookmarks menu item. Choose the File|Import menu item in the Bookmarks window. These commands read any HTML file containing links and convert the links into bookmarks.
To import a hotlist into Netscape, you should first convert your hotlist to HTML. Several downloadable utilities perform this conversion. You can also use another browser's mail command to transmit a hotlist in HTML format.
How can I save files and images onto my hard disk?
Choose File|Save As to save a page locally (to your hard disk) in source, text, or PostScript format (UNIX only). Source format produces a text file encoded with the HTML necessary to reproduce the formatted text or image faithfully; text format saves text without the HTML code. Where some links, such as many FTP links, automatically download and save a file to disk, Save As manually saves page files.
You can also save a page to disk without displaying the page onscreen. Position the mouse over a link or image, then click the right mouse button (on Macintosh, hold down the button) to produce a pop-up menu with the items Save this Link as and Save this Image as for saving a file. Clicking on any link with the Shift key depressed (Option key on Macintosh) also produces a save dialog.
Saving a file to your hard disk allows you to display the page's information without any network connection. You can choose File|Open File to display the HTML-formatted text or graphic image of any local file saved in source format (though a page's inline images might be replaced with icons).
On Windows, you'll need to select "All Files" for GIF, JPEG, or other nontext files to show up in the Open File dialog. On Macintosh, GIF and JPEG images are available in the Open File dialog, though for other nontext files to show up, you'll need to hold down the Option key while selecting the Open File menu item.
The pop-up menu item View this Image lets you see an isolated image file. The pop-up menu item Copy this Image Location copies the URL of the image file to the clipboard. Once you have the URL, you can open the image and save the image to your hard disk in source format using File|Save As or the pop-up menu. You could also use View|Document Source to find the URL of an inline image embedded in HTML code).
What is dithering and how is it used?
Dithering is a software imaging process for arranging adjacent pixels of varying shades to achieve a visual effect. The process often enhances a computer's ability to display an image, and is particularly useful when the color or resolution of the original image must be reproduced on computers with different display capabilities.
Netscape's display of inline GIF and JPEG sometimes needs to translate an image's colors into similar colors available on your computer. If your computer doesn't have color capabilities that match the color information in an image, the image might look speckled.
On Windows and UNIX, you can set radio buttons in the General|Images panel to Automatic, Dither, or Substitute Colors. JPEG images, however, are always dithered.
The default choice, Automatic, lets Netscape choose the image display determined to be most appropriate. When you choose to Dither, Netscape dithers the computer's available colors to most closely match the image's colors. When you choose Substitute Colors, Netscape substitutes an available color that most closely matches the image's colors. Images that are displayed with dithering take slightly more time to display than images using color substitution.
On Macintosh, dithering for all images is built-in and cannot be turned off.
How does Netscape work as an OLE server and container?
The OLE (Object Linking and Embedding) specification provides a way for OLE-compliant applications to work embedded within one another. An application that is an OLE server can operate within an OLE container.
For example, Netscape, acting as an OLE server, can be displayed within a container application such as Wordpad or Excel. In this manner, you can have a fully capable web browser inserted into your documents or spreadsheets. Likewise, Netscape, acting as an OLE container, can display an application such as Wordpad or Excel provided that the page's HTML uses the EMBED tag to designate the embedded server document.
A OLE server can be activated in place. Thus, when you activate (double-click) the OLE object, the object remains stationary and functions within the application (not spawning a new window). OLE servers also have the capability to be mini servers (for OLE 1 compatibility). When you activate a mini-server in your container document, the native application is activated and functions in a new window. Most OLE 2 containers, including Netscape, can be made to act as an OLE 1 container by holding down the Ctrl key and double-clicking the embedded OLE object.
OLE servers, when activated in place, take over the user interface of their host. For example, if you create a Word document, insert a Netscape object, then double-click on the embedded Netscape application, the Word toolbar is replaced with the Netscape toolbar and the Word menus change to display the relevant Netscape menus.
What is autoscroll and how does it support chat?
Autoscroll is a feature of Netscape that lets a server deliver ongoing page information to your screen automatically. The connection to the server is kept open and new page information is appended. The autoscroll areas (a page or page frame) automatically scrolls to accommodate the data stream. Both autoscroll and server push leave the connection to the server open and display new content on an ongoing basis; however, autoscroll appends new information to the page whereas server push updates the entire page. You can close the connection by bringing a new page.
The autoscroll feature can support an online chat session with another user. You can view incoming text automatically without having to use the scroll bar to move down the page. You can also output text at the same time in an adjacent window without interrupting the incoming text stream.
To implement the autoscroll feature, page creators and server administrators use Netscape's autoscrolling tool. Autoscroll is an HTTP header attribute. The content-type modifier AUTOSCROLL is similar to CHARSET.
As new text arrives into the autoscroll area, the text scrolls to keep the most recent line of transmitted text on the screen. You can scroll up to view previous text without having to watch the text stream, and can scroll down to again view the incoming stream. The autoscroll area can display a maximum of 1000 lines and consists of two components:
Plug-in modules are software programs that extend the capabilities of Netscape. A plug-in is installed on your hard disk using instructions that come with the plug-in. After installation, Netscape uses the plug-in's capabilities like other built-in Netscape features.
The plug-in application programming interface (API) allows third parties to extend Netscape with native support for new data types and additional features. Plug-ins are dynamic code modules, native to each Netscape platform. Plug-ins are complementary to architectures such as OLE and platform-independent programming languages such as Java. Here are the primary goals of the plug-in API:
The Netscape user interface remains relatively unchanged even when plug-ins are in use. Frames without plug-in data function like ordinary frames. Basic operations such as navigation, history, and opening files are not changed by plug-ins.
A plug-in can retrieve a URL with the same network functionality as Netscape. The data from such a URL is provided as a stream as the data arrives from the network. Plug-ins can themselves generate data that Netscape or other plug-ins can display. Plug-ins can both produce and consume data.
Plug-ins are associated with a MIME data type that Netscape does not natively support. When Netscape encounters an unknown data type from a server, Netscape looks for a plug-in that is associated with that MIME type and loads the plug-in.
What is a cache and how does it work?
A cache temporarily stores the information on a page in your computer. The first time you ask for a page, Netscape retrieves the page from the network. No pages are permanently stored in a cache. If you request a page you have seen before, Netscape checks to see if the page is available in a cache. For example, if you use the Back button to display a page, a cache can display the page more quickly than the network can retransmit it.
Sometimes you might not want a page to be retrieved from a cache. The page you displayed initially may be different than the page currently offered by the network. If a modification to a particular URL has occurred, you may want the updated page rather than the copy (now stale) stored in a cache. Remember, you have no control over when a server updates its pages.
When you click on a link, choose a bookmark, enter a URL, or press the Reload button, Netscape checks with the server to see if an update has occurred before bringing a page from a cache. If any change to the page has occurred, a fresh version is transmitted over the network; otherwise, a copy is quickly retrieved from a cache.
If you press the Reload button while holding down the Shift key (Option key on Macintosh), Netscape retrieves a fresh version from the network regardless of whether the page has been updated. The cache is not used. This type of reload is useful if you suspect the cached copy of a page has been corrupted.
When you press the Back button or choose a history item, Netscape does not check the network. Since you are explicitly requesting a previously viewed page, Netscape tries first to retrieve the cached copy (if still present in the cache) even if the server offers a more recent version.
What is the difference between memory cache and disk cache?
Netscape supports memory and disk cache to improve performance and reduce network traffic. When you bring a page from the network, information is stored in both caches. Netscape retrieves a page from the memory cache more quickly than from the disk cache, though retrieving from the disk cache is still faster than fetching from the network.
The disk cache has the advantage of persistence. When you exit a session (quit the Netscape application), the memory cache is emptied, but the disk cache is maintained (and takes up space on your hard disk).
Sometimes a cache can get confused (such as when servers provide inaccurate page modification dates). If you suspect a cache is acting improperly (such as providing stale pages) or just wish to free up space, you can clear the caches by pressing the Clear Memory Cache Now and Clear Disk Cache Now buttons in the Network|Cache panel (Clear Disk Cache Now is only on Macintosh).
What is the recommended size for each cache?
You can change the size of each cache to maximize its effectiveness. A larger cache might increase Netscape performance, though allocating too much space can constrict other applications. You might try to increase the size of the memory cache to whatever your system routinely has unused and increase the disk cache to between 2,000 and 5,000 kilobytes (2 and 5 megabytes).
You might find that a large disk cache increases the time required for the Netscape application to quit. If Netscape's cache maintenance causes undue delay when you exit the program, consider reducing size of the disk cache.
On Windows and UNIX, cache size and location preferences are set in the Network|Cache panel. An editable field in the panel allows you to set the directory location of the disk cache.
On Macintosh, the memory cache size is set in the Get Info dialog box: from the Finder, select the Netscape application and choose the File|Get Info menu item. The disk cache size and location are set in the Network|Cache panel. A Browse button in the dialog box allows you to set the directory location of the disk cache. By default, Netscape places the Macintosh disk cache inside the Netscape Preferences folder within the System Folder.
Are there any Macintosh-specific tips or tricks?
To create a Bookmark shortcut, drag the page icon from the Bookmark window onto the desktop. Note that you can create an HTML copy of a page by dragging and dropping a page link onto the desktop, however a copy of a page is a text file and differs from a bookmark to a page.
Once you have created the Bookmark shortcut icon, you can double-click on the icon to automatically open the shortcut page. You can also open the page by dragging and dropping the icon onto the Netscape window. Even if the Netscape application is not running, you can drag and drop the shortcut icon on top of the Netscape application icon to open Netscape with the shortcut page automatically loaded.
Keyboard shortcuts
Are there any Windows-specific tips or tricks?
[Netscape] ini=for the location of the netscape.ini file (the INI file contains initializations and preference settings used internally by Netscape). If the file doesn't exist, Netscape looks for the file in the directory where the application runs. You might also be able to copy your INI file from other browsers to the netscape.ini file. Be sure to add fields for History File and File Location, and to convert hotlist entries to Netscape bookmarks.
How do Windows 95 shortcuts work?
Internet shortcuts are available on the Windows 95 version of Netscape. These shortcuts let you double-click on a desktop icon to open Netscape with a particular page automatically loaded. The desktop icon functions as a stand-alone bookmark, opening the Netscape application (if necessary) and displaying onscreen the page whose URL is stored as part of the shortcut.
To create an Internet shortcut for the page you are viewing, drag the URL link icon (the small icon to the left of the location field) onto the desktop.
To create an Internet shortcut for any page, press the right mouse button to display the pop-up menu and select the Create Shortcut item. This displays the Create Internet Shortcuts dialog box containing a Description field and a URL field.
By default, the Description field is preset with the words Shortcut to followed by the title of the page you are viewing and the URL field is preset with the the page's URL. You can modify the contents of either field to specify any page you wish. Click the OK button to create the Internet shortcut. The icon appears on the desktop.
To create an Internet shortcut for a page in your bookmark list, drag the page icon from the Bookmark window onto the desktop. You can also create an Internet shortcut for a particular page by dragging and dropping a page link onto the desktop.
Once you have created the Internet shortcut icon, you can drag and drop the shortcut icon (like a bookmark) onto the Netscape window to automatically open the shortcut page. Even if the Netscape application is not running, you can drag and drop the shortcut icon on top of the Netscape application icon to open Netscape with the shortcut page automatically loaded.
Are there any UNIX-specific tips or tricks?
-geometry =620x950+630+40or this X resource:
Netscape*TopLevelShell.geometry: =620x950+630+40To set sizes of individual windows set the following X resources:
netscape*Navigator.geometry: WxH+X+Y (Netscape window) Netscape*Mail.geometry: WxH+X+Y (Mail window) Netscape*News.geometry: WxH+X+Y (News window) Netscape*Bookmark.geometry: WxH+X+Y (Bookmark window) Netscape*AddressBook.geometry: WxH+X+Y (Address Book window) Netscape*Composition.geometry: WxH+X+Y (Message Composition window) Netscape*TopLevelShell.geometry: WxH+X+Y (sets all of the above windows to be the same size.)The -geometry command-line option sets the sizes of the Netscape, Mail, and News windows.
The following fonts are used in the window outline lists. Note that no white space follows the commas.
*XmLGrid*fontList:\ -*-helvetica-medium-r-*-*-*-100-*-*-*-*-iso8859-*,\ -*-helvetica-bold-r-*-*-*-100-*-*-*-*-iso8859-*=BOLD,\ -*-helvetica-medium-o-*-*-*-100-*-*-*-*-iso8859-*=ITALIC
-help (lists all options) -geometry =WxH+X+Y (to position and size the window) -visual(to use a specific server visual) -install (to install a private colormap) -no-install (to use the default colormap) -ncols (when not using -install, set the maximum number of colors to allocate for images) -mono (force 1-bit-deep image display) -xrm (to set a specific X resource) -remote (to execute a command in an already-running Netscape process) -id (the id of an X window to send the -remote commands; if unspecified, the first window found is used)
How can I access the Internet?
Some companies maintain a network that is linked to the Internet via dedicated communication lines. Those with less substantial resources, including most individuals, access the Internet via a service provider. A service provider is a company that offers use of its dedicated communication lines. If you have a modem, you can dial up a service provider whose computers will connect you to the Internet, typically for a fee. Dial-up access means that the modem on your computer can log in to another computer that is hooked up to the Internet.
The most popular dial-up access alternatives are shell accounts and SLIP/PPP accounts. When using a shell account, you dial into a service provider's computer and use the UNIX operating system to indirectly connect to the Internet. With an indirect connection, your computer does not interact with Internet computers. In many cases, when you download a file from an Internet site, the file is saved on the service provider's computer rather than on your computer. You then have to transfer the file from the service provider's computer to your home system. Shell accounts, while limited in features, have historically been less expensive than direct access accounts.
When using a SLIP or PPP account, you dial into a service provider's computer and run applications that directly connect to the Internet. With a direct connection, your computer can use browsers with user-friendly graphical interfaces to interact with Internet computers. A direct connection lets you download files directly to your system from remote sites. SLIP or PPP access to the Internet offers more performance and convenience than a shell account.
SLIP, short for Serial Line Internet Protocol, and PPP, short for Point-to-Point Protocol, are Internet standards for transmitting Internet Protocol (IP) packets over serial lines (phone lines). Internet information is packaged into IP packets, a method for enclosing data into small, transmittable units (wrapped up on one end, unbundled on the other).
A service provider might offer SLIP, PPP, or both. Your computer must use connection software (usually provided by the service provider) that matches the protocol of the server's connection software. PPP is a more recent and robust protocol than SLIP.
What should I know about firewalls?
A firewall protects one or more computers with Internet connections from access by external computers connected to the Internet. A firewall is a network configuration, usually created by hardware and software, that forms a boundary between networked computers within the firewall from those outside the firewall. The computers within the firewall are a secure subnet with internal access capabilities and shared resources not available to the computers on the outside.
Often, a single machine atop the firewall is allowed access to both internal and external computers. Since the computer atop the firewall is directly interacting with the Internet, strict security measures against unwanted access from external computers are required.
A firewall is commonly used to protect information such as a network's email and data files within a physical building or organization site. A firewall reduces the risk of intrusion by unauthorized people from the Internet, however, the same security measures can limit or require special software for those inside the firewall who wish to access information on the outside. A firewall can be configured using proxies (or SOCKS) to designate access to information from each side of the firewall.
Sometimes you need to restart Netscape after changing the SOCKS host. Netscape supports version 4 of SOCKS, defined by the socks.cstc.4.1 implementation.
Some information on the Internet is offered through Gopher servers. When you want information that happens to be on a Gopher server, you'll click on a link whose URL begins with gopher (or enter the URL in the location field).
Netscape lets you access Gopher servers in the same way you access World Wide Web (HTTP) pages. Though Gopher pages lack rich formatting, menu listings allow you to display content pages or additional menu sublistings.
A menu is presented as a list of links, each link preceded by a small icon indicating the type of resource the link displays. For example, Gopher links can bring you
Some files, such as short digital movies, require the use of Netscape's helper applications. If available, Netscape automatically launches the helper application required by a Gopher link.
How do I download and upload files using FTP?
By accessing a page whose URL begins with ftp (short for file transport protocol), you can navigate directories, view files (including HTML and image files), download software, and upload software. For example, you might use links to FTP server sites for downloading updates to Netscape and helper application software.
Netscape lets you access FTP servers in the same way you access World Wide Web (HTTP) servers. However, you may find the FTP directory and content pages have minimal formatting. When possible, Netscape shows the type, size, date and a short description of each file in a directory. A directory is presented as a list of links, each link often preceded by a small icon indicating another directory or a file. Clicking on a directory link displays a subdirectory. Typically, at the top of a subdirectory is a link that displays the parent directory.
Clicking on a binary file or program automatically downloads the software to a folder (designated in the General|Helpers panel) on your computer. After downloading, Netscape automatically looks for a suitable helper application to launch the file. If the necessary helper application is not available, a dialog box asks whether you want to save or discard the downloaded software.
Note that not all files are downloaded using FTP. By using the pop-up menu or by clicking on a link with the Shift key held down (Option key on Macintosh), you produce the dialog box for saving an HTTP page, an image file, or other file type to disk.
After you have accessed an FTP server, you can upload files to the site by dragging and dropping files from the desktop to the Netscape browser. Alternatively, after you've accessed an FTP site, choose the File|Upload File menu item. In the resulting dialog box, select the file on your hard disk that you wish to upload. Note that you must have write access to the FTP server (permission granted from the site) to upload files.
Where do I find helper applications?
Choose the Help|Frequently Asked Questions menu item, click on the Netscape Navigator FAQ link, then click the System Requirements link to find sites for downloading helper application software. To install and configure helper applications (many are already configured), choose the Options|General|Helpers menu item to display the Helpers panel.
Helper applications expand Netscape's abilities by letting you automatically decompress downloaded applications, listen to sounds, play movies, and get better display of images. Most can be obtained free or as shareware.
Compression: You might find that some programs are stored on the Internet in formats your computer doesn't understand. You'll want to locate a helper application program like PKUNZIP (Windows) or Stuffit Expander (Macintosh) to translate and decompress downloaded software (and other helper applications).
Sounds: Most sound files aren't in a format that your computer can automatically play. To listen to the different types of sound files such as ULAW (common .au files), AIFF, and WAV, you'll need to install a helper application that understands them.
Pictures and Movies: Netscape can display GIF, JPEG, and XBM files internally, but you might prefer to use a dedicated image viewer. To have Netscape automatically launch an external viewer, select the Mime Type in the list, then choose the radio button Launch Application. (On UNIX, you'll use a .mailcap file to supply a path and file name.) You'll need a player to view mpeg movies.
What are the MIME types used by helper applications?
HTTP servers use HTML formatting. Netscape software has the built-in capability to read HTML-formatted pages (as well as the GIF, JPEG, and XBM graphic file formats). Netscape can interpret many other file formats with the help of external helper applications. To accommodate the file formats requiring helper applications, Netscape keeps a mapping of file formats to helper applications.
MIME (Multipurpose Internet Mail Extensions) is a standardized method for organizing divergent file formats. The method organizes file formats according to the file's MIME type. When Netscape software retrieves a file from a server, the server provides the MIME type of the file. Netscape uses the MIME type to establish whether the file format can be read by the software's built-in capabilities or, if not, whether a suitable helper application is available to read the file.
For servers that do not provide a MIME type with a file, Netscape interprets the file's extension (a suffix appended to a file name). For example, the .htm extension in the file name index.htm suggests a file in the HTML format. Likewise, a .zip extension suggests a compressed file, an .rtf extension suggests a file in the Rich Text Format, and so on. You can view and configure the mapping of all MIME types to helper applications by using the General|Helpers panel. (On UNIX, edit your global or personal MIME types file whose pathname is designated.)
Note that on Windows the panel currently lacks a Delete button and the ability to assign arbitrary values to file types. If needed, advanced users might want to edit the preferences file directly.
What are MIME, Types files, and Mailcap files?
The MIME protocol is used in Internet communications to transmit documents of varying formats. The protocol handles complexities by establishing a relationship (a mapping) between the format of a document's content and the format of the document's computer representation. Applications using MIME can establish the type of software necessary to interpret the content of a transmitted document. With the proper Helper Application settings and software, Netscape can automatically initiate the necessary actions to provide you access to content transmitted in numerous formats.
On Windows and Macintosh, the mapping of MIME types is handled in the General|Helpers panel. On UNIX, the mapping of MIME types uses two kinds of files: a Types file and a Mailcap file (each can be configured with global, default, and personal files).
A Types file maps a file format (on the left) with an identifying file name suffix (on the right). Here's a sample from a .mime.types file:
application/dvi dvi image/jpeg jpeg audio/basic au, wav
A Mailcap file maps a file format (on the left) with a software application capable interpreting the format (on the right). Here's a sample from a .mailcap file:
application/dvi; dvi-app-name %s image/*; xv %s audio/basic; audiotool %s
As an example, an audio file mySound.au plays using the audiotool application.
Where can I learn about Internet security?
The Internet security technology developed by Netscape Communications to ensure private and authenticated communications (called SSL, short for Secure Sockets Layer protocol) is an open platform put into the public domain for the Internet community. Netscape Navigator and Netscape's secure servers offer this nonproprietary technology. Choose the Help|On Security menu item for an overview of security implementation from Netscape Communications and a specification for the Secure Sockets Layer protocol.
The introductory information in the Netscape Navigator Handbook tells you why you need security on the Internet and how to recognize the security features built into Netscape Navigator.
Can I safely transmit information such as credit card numbers?
You can enter your credit card number on a secure (https) Netscape Navigator form and transmit the form over the Internet to a secure server without risk of an intermediary obtaining your credit card information. The security features offered by Netscape Communications technology protects commercial transactions, as well as all other communications, from misappropriation and fraud that could otherwise occur as information passes through Internet computers.
Secure communications does not eliminate all of an Internet user's concerns. For example, you must be willing to trust the server administrator with your credit card number before you enter into a commercial transaction. Security technology secures the routes of Internet communication; security technology does not protect you from unreputable or careless people with whom you might choose to do business.
The situation is analogous to telling someone your credit card number over the telephone. You may be secure in knowing that no one has overheard your conversation (privacy) and that the person on the line works for the company you wish to buy from (authentication), but you must also be willing to trust the person and the company.
Server administrators must take additional precautions to prevent security breeches. To protect your information, they must maintain physical security of their server computers and control access to software passwords and private keys.
How does Netscape's security technology protect me?
The security features built into Netscape Navigator and secure servers protect your Internet communications with:
Without thorough security, information transmitted over the Internet is susceptible to fraud and other misuse by intermediaries. Information traveling between your computer and a server uses a routing process that can extend over many computer systems. Any one of these computer systems represents an intermediary with the potential to access the flow of information between your computer and a trusted server. You need security to make sure that intermediaries cannot deceive you, eavesdrop on you, copy from you, or damage your communications. The Internet does not provide built-in security.
The SSL protocol delivers server authentication, data encryption, and message integrity. SSL is layered beneath application protocols such as HTTP, SMTP, Telnet, FTP, Gopher, and NNTP, and layered above the connection protocol TCP/IP. This strategy allows SSL to operate independently of the Internet application protocols.
With SSL implemented on both the client and server, your Internet communications are transmitted in encrypted form. Information you send can be trusted to arrive privately and unaltered to the server you specify (and no other).
To what degree can SSL security protect me?
SSL uses authentication and encryption technology developed by RSA Data Security Inc. For example, Netscape Navigator's export implementation of SSL (U.S. government approved) uses a medium-grade, 40-bit key size for the RC4 stream encryption algorithm. The encryption established between you and a server remains valid over multiple connections, yet the effort expended to defeat the encryption of one message cannot be leveraged to defeat the next message.
A message encrypted with 40-bit RC4 takes on average 64 MIPS-years to break (a 64-MIPS computer needs a year of dedicated processor time to break the message's encryption). The high-grade, 128-bit U.S. domestic version provides protection exponentially more vast. The effort required to break any given exchange of information is a formidable deterrent. Server authentication uses RSA public key cryptography in conjunction with ISO X.509 digital certificates.
Netscape Navigator and secure servers deliver server authentication using signed digital certificates issued by trusted third parties known as certificate authorities. A digital certificate verifies the connection between a server's public key and the server's identification (just as a driver's license verifies the connection between your photograph and your personal identification. Cryptographic checks, using digital signatures, ensure that information within a certificate can be trusted.
To evaluate the strategic and quantitative implications of the SSL implementation of certification and public key technology, consult the SSL Protocol specification via the Help|On Security menu item.
How can I tell when security is in effect?
You can tell when you have a secure connection by looking at the location (URL) field. If the URL begins with https:// (instead of http://), the document comes from a secure server. To connect to an HTTP server that provides security using the SSL protocol, insert the letter "s" so that the URL begins with https://. You need to use https:// for HTTP URLs with SSL and http:// for HTTP URLs without SSL. A news URL that starts with snews: (the letter "s" inserted in front of news:) is used for a document coming from a secure news server.
You can also verify the security of a document by examining the security icon in the bottom-left corner of the Netscape Navigator window and the colorbar across the top of the content area. The icon consists of a doorkey on a blue background to show secure documents and a broken doorkey on a gray background to show insecure documents. The doorkey has two teeth for high-grade encryption, one tooth for medium-grade. Clicking on a doorkey icon displays a dialog containing security information about a document. The colorbar across the top of the content area is blue for secure and gray for insecure.
A mixed document containing secure and insecure information is displayed as secure with insecure information replaced by a mixed security icon. Some servers may permit you access documents insecurely (using http://) to view mixed documents in full.
More detailed security information can be found by choosing the View|Document Info menu item. Several configurable notification dialog boxes inform you when you are entering or leaving a secure space, viewing a secure document that contains insecure information, and using an insecure submission process. You'll always be warned if a secure URL is redirected to an insecure location, or if you're submitting via a secure form using an insecure submission process.
The security protocol works as an adjunct to other protocols without limiting access capabilities. You can use Netscape Navigator to bring either secure or insecure documents. Online forms can be secure if the submit action is an https:// URL to a secure server.
You can save a secure document (though secure documents are not cached to disk among sessions). You can also view the HTML source of a secure document. Security affects the transmission of a document without affecting your ability to manipulate the document.
What does the Document Information page tell me?
Choosing the View|Document Info menu item produces a page with a document's structure, composition, and security status. Structure information contains the URLs of images contained in the document. Composition information includes location, file MIME type, source, local cache file, modification and expiration dates, content length, and charset. Security information informs you about encryption and certification.
Similar identifying information is provided about the certificate authority responsible for issuing the certificate. The certificate is identified by:
Are certificates required and where do you get one?
Personal certificates identify you to others on the Internet. They serve as digitally-signed identification cards. Certain sites might require that you present a personal certificate to access their servers.
To learn about personal certificates and how to obtain them, choose Options|Security Preferences|Personal Certificates and select the Obtain New Certificate button. This displays a page describing certification services and contains links to the certificate authorities that issue personal certificates.
Site certificates identify others on the Internet to you. They are issued to organizations running servers.
To operate using security features, a secure server requires a digitally signed certificate. Without a certificate, the server can only operate insecurely. If you are a server administrator and want to obtain a signed certificate, you need to submit a certificate request to a certificate authority. The process to obtain a site certificate is explained in Netscape's server documentation.
Netscape Communications Corporation does not issue certificates. Certificates are issued by a certificate authority, a third-party organization. Information about certificate classifications and associated service fees can be obtained directly from the certificate authority.
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