Mozilla networking preferences

Abstract

List of preferences that affect networking behavior.
Description of acceptable values and behavior.

Audience

QA testers, developers and "power users" with extensive networking internals experience.
For general technical documentation on preferences (including how to edit them), see "A Brief Guide to Mozilla Preferences"

The goal is to accurately document Core-Necko behavior and Firefox 3 UI.

Overview

The sections are in roughly alphabetical + functional order. The preferences are in order of usage by the UI (which is not often alphabetical order). Relevant bugs are provided only when absolutely necessary.

Note: Do not change any of these via about:config unless you know what you are doing. If you are uncertain what that phrase means, you probably do not.

If you qualify, you are probably one or more of the following:

You have a feature-spec or code-level understanding of the preference.
You are doing testing and have a clear performance metric.
You are doing this in conjunction with a packet trace to monitor Necko's changed behavior.

Preferences

HTTP (this section under construction)

Preference Name	Acceptable Values	Preferences UI (in bold) and comments
`general.useragent.contentlocale`	string
`general.useragent.misc`	(major version number) string
`general.useragent.security`	string
`network.http.accept-encoding`	`gzip,deflate` (default string)	no UI
`network.http.accept.default`	`text/xml,application/xml, application/xhtml+xml,text/html;` `q=0.9,text/plain;` `q=0.8,video/x-mng,image/png, image/jpeg,image/gif;` `q=0.2,/;q=0.1`
`network.http.default-socket-type`	(empty) default	?
`network.http.keep-alive`	`true` (default)
`network.http.keep-alive.timeout`	`30`	no UI
`network.http.max-connections`	`96`
`network.http.max-connections-per-server`	`32`
`network.http.max-persistent-connections-per-proxy`	`4`
`network.http.max-persistent-connections-per-server`	`8`
`network.http.pipelining` Obsolete since Gecko 54	`true`	Pipeline support was completely removed in Firefox 54. With the advent of HTTP/2 and other speed enhancements, pipelining of HTTP is no longer useful to maintain.
`network.http.pipelining.firstrequest` Obsolete since Gecko 54	`true`	Pipeline support was completely removed in Firefox 54. With the advent of HTTP/2 and other speed enhancements, pipelining of HTTP is no longer useful to maintain.
`network.http.pipelining.maxrequests` Obsolete since Gecko 54	`8`	Hard-coded to 8 max so 30 will have no greater effect Pipeline support was completely removed in Firefox 54. With the advent of HTTP/2 and other speed enhancements, pipelining of HTTP is no longer useful to maintain.
`network.http.proxy.keep-alive`	`true` (default)
`network.http.proxy.pipelining` Obsolete since Gecko 54	`true`	Pipeline support was completely removed in Firefox 54. With the advent of HTTP/2 and other speed enhancements, pipelining of HTTP is no longer useful to maintain.
`network.http.proxy.version`	`1.1` (default) `1.0`
`network.http.redirection-limit`	`20`
`network.http.request.max-start-delay`	`10`
`network.http.sendRefererHeader`	`2`
`network.http.sendSecureXSiteReferrer`	`true`
`network.http.use-cache`	`true`
`network.http.version`	`1.1` (default) `1.0`

File

Preference Name	Acceptable Values	Preferences UI and comments
`security.checkloaduri`	`true` (default) `false`	No UI `checkloaduri` will disable file:// URLs on pages from a network (http: https: ftp:) source, for security reasons. Errors are sent to the javascript console, not to the user via dialog box. This preference only works in Gecko versions before 1.8 (so Firefox 1.0 and Mozilla Suite builds). In Firefox 1.5 and Seamonkey 1.0 this preference no longer has an effect.

FTP (see also Proxy)

Preference Name	Acceptable Values	Preferences UI (in bold) and comments
`advanced.mailftp`	`false` (default) `true`	Preferences \| Advanced \| "[x] Set this email address as anonymous FTP password:" If false, FTP uses "`mozilla@example.com`" as anonymous FTP password (bug 101027) If true, FTP uses contents of `network.ftp.anonymous_password` for anonymous FTP password (bug 57763 comment 28)
`network.ftp.anonymous_password`	`empty` (default) any text string	Preferences \| Advanced \| (under "[ ] Set this email address as anonymous FTP password:") [text field] If empty, FTP uses "`mozilla@example.com`" as anonymous FTP password.
`network.ftp.idleConnectionTimeout`	`300` (default) any integer	No UI Measured in seconds The open connection can prevent other FTP clients on your system from connecting to sites that allow only one control connection (bug 117875)
`network.dir.format`	`0` = HTML view `1` = raw view `2` = HTML view `3` = XUL view	Preferences \| Debug \| Networking Networking Directory Listing Format ( ) HTML ( ) XUL (tree-based)

Cache

Preference Name	Acceptable Values	Preferences UI (in bold) and comments
`browser.cache.disk.capacity`	`256000` (default) any integer (in KB)	Preferences \| Advanced \| Cache Cache: [MB] MB Note: The default was 51200 prior to Gecko 9.0 (Firefox 9.0 / Thunderbird 9.0 / SeaMonkey 2.6).
`browser.cache.disk.parent_directory`	path to Cache folder in profile (default)	Cache Folder: [text box] Note: The contents of the disk and memory caches are different (a very large memory cache is not the same as pointing disk cache to memory mapped disk space (RAM disk).
`browser.cache.disk.max_entry_size`	`51200` (default) -1 = no limit	The maximum size of an entry in the disk cache. Note: Items larger than 1/8 of `browser.cache.disk.capacity` are never cached.
`browser.cache.check_doc_frequency`	`1` = Every time I view the page `0` = Once per session `3` = When the page is out of date (default) `2` = Never	Compare the page in cache to the page on the network:
`browser.cache.disk.enable`	`true` (default)	Preferences \| Debug \| Cache [x] Enable Disk Cache [x] Enable Memory Cache Disabling disk cache has the effect of setting it to zero.
`browser.cache.memory.enable`	`true` (default)
`browser.cache.memory.capacity`	any integer (in KB)	Replaced by automatic sizing in Mozilla 1.4b (bug 105344). This value overrides the application. 0 disables feature (before, `4096` = default)
`browser.cache.memory.max_entry_size`	`5120` (default) -1 = no limit	The maximum size of an entry in the memory cache (in KB). Note: Items larger than 90% of `browser.cache.memory.capacity` are never cached.
`network.http.use-cache`	`true` (default)	no UI
`browser.cache.disk_cache_ssl`	`false` (default)	no UI, added in 1.6a (see bug 205921)
`network.prefetch-next`	`False`	Preferences \| Advanced \| Cache: Link Prefetching [x] Prefetch web pages when idle, so that links in web page designed for prefetching can load faster.
`browser.cache.disk.smart_size.first_run`	`true` (default)	Indicates whether or not this is the first time smart sizing has been used.
`browser.cache.disk.smart_size.enabled`	`true` (default)	Indicates whether or not smart sizing of the disk cache is enabled.

DNS

Preference Name	Acceptable Values	Preferences UI (in bold) and comments
`network.dnsCacheExpiration`	`60` (seconds)	default pref-less, not visible in about:config. Create and set both values to "0" to disable.
`network.dnsCacheEntries`	`20` (entries)

Cookies

The old section in this document was removed because of dwitte's cookies re-write. Please see: Cookies Preferences in Mozilla

Proxy

Note: Do NOT use this in extensions, use nsIProtocolProxyFilter [en-US] instead.

Preference Name	Acceptable Values	Preferences UI (in bold) and comments
`network.proxy.type`	`0` = direct `1` = manual `2` = PAC `3` = mapped to 0 `4` = WPAD	Preferences \| Advanced \| Proxies Configure Proxies to Access the Internet ( ) Direct connection to the internet ( ) Auto-detect proxy settings (new in 1.8) ( ) Manual proxy configuration ( ) Automatic proxy configuration URL 3 was old Communicator value for DIRECT.
`network.proxy.http`	<Protocol> Proxy: hostname or IPv4 is acceptable. IPv6 needs to be tested. Port: 0 will cause server:port preference for that manual proxy type to be ignored. 1-65xxx is valid range	Affects `http:` URLs
`network.proxy.http_port`		Affects `http:` URLs
`network.proxy.ssl`		Affects `https:` URLs Possibly affects SIMAP and SNEWS
`network.proxy.ssl_port`		Affects `https:` URLs Possibly affects SIMAP and SNEWS
`network.proxy.ftp`		Affects `ftp:` URLs
`network.proxy.ftp_port`		Affects `ftp:` URLs
`network.proxy.socks`		Used when application-specific proxy is not configured. Possibly affects other protocols
`network.proxy.socks_port`
`network.proxy.socks_version`		`5` (default) `4`	Protocol version to use when speaking with the SOCKS server
`network.proxy.socks_remote_dns`		`false` (default) `true`	If SOCKS 5 is specified, then DNS lookups can be performed on the SOCK proxy server. This flag controls whether lookups are done locally or on the SOCKS server. Note: SOCKS 4 servers do not support DNS lookups.
`network.proxy.proxy_over_tls`	`false` (default) `true`	Connect to the proxy server using SSL/TLS. More info.
`network.proxy.no_proxies_on`	`localhost, 127.0.0.1` (default) string of comma delimited fqdn's, hostnames, IPv4 addresses and CDIR blocks. See No Proxy For configuration.	Localhost is not proxied by default, bug 31510.
`network.proxy.autoconfig_url`	empty (default) URL string	must be absolute URl, no hostname
`network.proxy.failover_timeout`	`1800` (default, 30 minutes) Positive integer	Number of minutes to wait for primary proxy server connection to fail and switch to the failover server.

Online

Preference Name	Acceptable Values	Preferences UI (in bold) and comments
`network.online`	`true` = Mozilla is online (default) `false` = Mozilla is offline	Necko updates the offline\|online status to this value. Changing this value does not change the actual networking status. Value is not updated if "Ask me for online state at startup" was selected for the current profile (bug 229677).
`offline.startup_state`	`0` = use network.online (default) `1 = prompt user`	Preferences: Mail & Newsgroups \| Offline \| When starting up: (Pref affects all modules, but was moved from Pref root, bug 202529) [x] Remember previous online state (Uses network.online to set online\|offline status at startup) [ ] Ask me for online state at startup (Unlike Communicator, prompt always appears, bug 239564)

Gopher (see also Proxy)

Preference Name	Acceptable Values	Comments (bold for areas that user configures)
`network.dir.format`	see FTP Obsolete since Gecko 2.0

Unsupported

Preference Name	Acceptable Values	Comments (bold for areas that user configures)
`browser.xul.error.pages.enabled`	`false` (default) `true`	Does not appear in about.config unless added explicitly. See bug 28586)
`network.protocol-handler.external.SCHEME`	`false` (default) `true`	Mac+Windows: sends URLs of <SCHEME> to the default OS handler Linux/UNIX: sends URLs to application For example: `network.protocol-handler.external.mailto==true` is used by Phoenix/Firebird/Firefox to access default mailers. Handlers loaded before prefs are read cannot be redirected (e.g. file:)

Obsolete/Removed (this is list is incomplete)

browser.cache.enable
browser.cache.disk.directory
networking.proxy.wais
networking.proxy.wais_port
network.http.connect.timeout
network.http.proxy.ssl.connect
network.proxy.gopher Obsolete since Gecko 2.0
network.proxy.gopher_port Obsolete since Gecko 2.0

Under Investigation

offline.startup_state

Original Document Information

Author(s): Benjamin Chuang
Last Updated Date: July 26, 2007
Copyright Information: Portions of this content are © 1998–2007 by individual mozilla.org contributors; content available under a Creative Commons license | Details.