Channel modes
There are also some channel modes which can be very effective against floods. To name a few:
K = no /knock, N = no nickchanges, C = no CTCPs, M = only registered users can talk, j = join throttling (per-user basis)
As of beta18 there's also a much more advanced channelmode +f...
Channel mode f
Instead of using scripts and bots to protect against channel floods it is now build into the ircd.
An example +f mode is: *** Blah sets mode: +f [10j]:15
This means 10 joins per 15 seconds are allowed in the channel, if the limit is hit, the channel will be set +i automatically.
The following floodtypes are available:

type:	name:	default action:	other avail. actions:	comments
c	CTCPs	auto +C	m, M
j	joins	auto +i	R
k	knocks	auto +K		(counted for local clients only)
m	messages/notices	auto +m	M
n	nickchanges	auto +N
t	text	kick	b	per-user messages/notices like the old +f. Will kick or ban the user.

  Example:

*** ChanOp sets mode: +f [20j,50m,7n]:15
<ChanOp> lalala
*** Evil1 (~fdsdsfddf@Clk-17B4D84B.blah.net) has joined #test
*** Evil2 (~jcvibhcih@Clk-3472A942.xx.someispcom) has joined #test
*** Evil3 (~toijhlihs@Clk-38D374A3.aol.com) has joined #test
*** Evil4 (~eihjifihi@Clk-5387B42F.dfdfd.blablalba.be) has joined #test
-- snip XX lines --
*** Evil21 (~jiovoihew@Clk-48D826C3.e.something.org) has joined #test
-server1.test.net:#test *** Channel joinflood detected (limit is 20 per 15 seconds), putting +i
*** server1.test.net sets mode: +i
<Evil2> fsdjfdshfdkjfdkjfdsgdskjgsdjgsdsdfsfdujsflkhsfdl
<Evil12> fsdjfdshfdkjfdkjfdsgdskjgsdjgsdsdfsfdujsflkhsfdl
<Evil15> fsdjfdshfdkjfdkjfdsgdskjgsdjgsdsdfsfdujsflkhsfdl
<Evil10> fsdjfdshfdkjfdkjfdsgdskjgsdjgsdsdfsfdujsflkhsfdl
<Evil8> fsdjfdshfdkjfdkjfdsgdskjgsdjgsdsdfsfdujsflkhsfdl
-- snip XX lines --
-server1.test.net:#test *** Channel msg/noticeflood detected (limit is 50 per 15 seconds), putting +m
*** server1.test.net sets mode: +m
*** Evil1 is now known as Hmmm1
*** Evil2 is now known as Hmmm2
*** Evil3 is now known as Hmmm3
*** Evil4 is now known as Hmmm4
*** Evil5 is now known as Hmmm5
*** Evil6 is now known as Hmmm6
*** Evil7 is now known as Hmmm7
*** Evil8 is now known as Hmmm8
-server1.test.net:#test *** Channel nickflood detected (limit is 7 per 15 seconds), putting +N
*** server1.test.net sets mode: +N

Basic bantypes and cloaked hosts
UnrealIRCd supports the basic bantypes like +b nick!user@host.
Also, if a masked host of someone is 'rox-ACB17294.isp.com' and you place a ban *!*@rox-ACB17294.isp.com, then if the user sets himself -x (and his hosts becomes for example 'dial-123.isp.com) then the ban will still match. Bans are always checked against real hosts AND masked hosts.
IP bans are also available (eg: *!*@128.*) and are also always checked.

Bans on cloaked IPs require some explanation:
If a user has the IP 1.2.3.4 his cloaked host could be 341C6CEC.8FC6128B.303AEBC6.IP.
If you ban *!*@341C6CEC.8FC6128B.303AEBC6.IP you would ban *!*@1.2.3.4 (obvious...)
If you ban *!*@*.8FC6128B.303AEBC6.IP you ban *!*@1.2.3.*
If you ban *!*@*.303AEBC6.IP you ban *!*@1.2.*
This information might be helpful to you when deciding how broad a ban should be.

Extended bantypes
Extended bans look like ~<type>:<parameter>.
They let you ban (or exempt) based on things other than the traditional nick!user@host mask. They also provide support for things like 'quieting' users.

These bantypes specify which actions are affected by a ban:

type:	name	explanation:
~q	quiet	People matching these bans can join but are unable to speak, unless they have +v or higher. Ex: ~q:*!*@blah.blah.com
~n	nickchange	People matching these bans cannot change nicks, unless they have +v or higher. Ex: ~n:*!*@*.aol.com
~j	join	If a user matches this, he may not join the channel. He may perform all other activities if he is already on the channel, such as speaking and changing his nick. Ex: ~j:*!*@*.aol.com Could be useful to prevent people from one ISP from joining, but still make them able to speak/nickchange freely once in the channel, like after an /INVITE.

These bantypes introduce new criteria which can be used:

type:	name	explanation:
~c	channel	If the user is in this channel then (s)he is unable to join. A prefix can also be specified (+/%/@/&/~) which means that it will only match if the user has that rights or higher on the specified channel. Ex: +b ~c:#lamers, +e ~c:@#trusted
~r	realname	If the realname of a user matches this then (s)he is unable to join. Ex: ~r:*Stupid_bot_script* NOTE: an underscore ('_') matches both a space (' ') and an underscore ('_'), so this ban would match 'Stupid bot script v1.4'.
~R	registered	If a user has identified to services (usually NickServ) and matches this nickname, then this ban will match. This means this ban is really only useful for ban exemptions (+e). Ex: +e ~R:Nick will allow Nick in the channel, regardless of other bans, if he identified to NickServ and is using the nickname Nick.

You may stack extended bans from the 1st group with the 2nd, such as +b ~q:~c:#lamers, which would quiet all users who have joined #lamers.

Modules can add other extended ban types.

Mode flags set on users. Many can be set by using the /mode Nickname command. For instance, if your nickname is "Simba", you could remove mode "x" from yourself by doing /mode Simba -x

NOTE: the /helpop documentation is more up to date, use /helpop command (or /helpop ?command if you are oper) to get more information on a command.

The FAQ is available online here

Regular expressions are used in many places in Unreal, including badwords, spamfilter, and aliases. Regular expressions are a very complex tool used for pattern matching. They are sometimes referred to as "regexp" or "regex." Unreal uses the TRE regular expression library for its regex. This library supports some very complex and advanced expressions that may be confusing. The information below will help you understand how regexps work. If you are interested in more technical and detailed information about the regexp syntax used by Unreal, visit the TRE homepage.

Literals are the most basic component of a regexp. Basically, they are characters that are treated as plaintext. For example, the pattern "test" consists of the four literals, "t," "e," "s," and "t." In Unreal, literals are treated as case insensitive, so the previous regex would match "test" as well as "TEST." Any character that is not a "meta character" (discussed in the following sections) is treated as a literal. You can also explicitely make a character a literal by using a backslash (\). For example, the dot (.) is a metacharacter. If you wish to include a literal ., simply use \. and Unreal will treat this as a period. It is also possible that you want to check for a character that is not easily typed, say ASCII character 3 (color). Rather than having to deal with using an IRC client to create this character, you can use a special sequence, the \x. If you type \x3, then it is interpretted as being the ASCII character 3. The number after the \x is represented as hexidecimal and can be in the range from \x0 to \xFF.

The dot (.) operator is used to match "any character." It matches a single character that has any value. For example, the regex "a.c" will match "abc," "adc," etc. However, it will not match "abd" because the "a" and "c" are literals that must match exactly.

One of the common mistakes people make with regex is assuming that they work just like wildcards. That is, the * and ? characters will match just like in a wildcard. While these characters do have similar meaning in a regex, they are not exactly the same. Additionaly, regular expressions also support other, more advanced methods of repetition.

The most basic repetition operator is the ? operator. This operator matches 0 or 1 of the previous character. This, "of the previous character," is where the ? in regex differs from a wildcard. In a wildcard, the expression, "a?c" matches an "a" followed by any character, followed by a "c". In regex it has a different meaning. It matches 0 or 1 of the letter "a" followed by the letter "c". Basically, the ? is modifying the a by specifying how many a's may be present. To emulate the ? in a wildcard, the . operator is used. The regex "a.c" is equivilent to the previously mentioned wildcard. It matches the letter "a" followed by any character, followed by a "c".

The next repetition operator is the *. Again, this operator is similar to a wildcard. It matches 0 or more of the previous character. Note that this "of the previous character" is something that is characteristic of all repetition operators. The regex "a*c" matches 0 or more a's followed by a "c". For example, "aaaaaac" matches. Once again, to make this work like a wildcard, you would use "a.*c" which will cause the * to modify the . (any character) rather than the "a."

The + operator is very similar to the *. However, instead of matching 0 or more, it matches 1 or more. Basically, "a*c" will match "c" (0 a's followed by a c), where as "a+c" would not. The "a+" states that there must be "at least" 1 a. So "c" does not match but "ac" and "aaaaaaaaac" do.

The most advanced repetition operator is known as a "boundary." A boundary lets you set exact constraints on how many of the previous character must be present. For example, you may want to require exactly 8 a's, or at least 8 a's, or between 3 and 5 a's. The boundary allows you to accomplish all of these. The basic syntax is {M,N} where M is the lower bound, and N is the upper bound. For example, the match between 3 and 5 a's, you would do "a{3,5}". However, you do not have to specify both numbers. If you do "a{8}" it means there must be exactly 8 a's. Therefore, "a{8}" is equivilent to "aaaaaaaa." To specify the "at least" example, you basically create a boundary that only has a lower bound. So for at least 8 a's, you would do "a{8,}".

By default, all of the repetition operators are "greedy." Greediness is a somewhat complex idea. Basically, it means that an operator will match as many characters as it can. This is best explained by an example.

Say we have the following text:
HELLO
And the following regex:
.+L

In this example, you might think that the .+ matches "HE." However, this is incorrect. Because the + is greedy, it matches "HEL." The reason is, it chooses the largest portion of the input text that can be matched while still allowing the entire regex to match. In this example, it chose "HEL" because the only other requirement is that the character after the text matched by .+ must be an "L". Since the text is "HELLO", "HEL" is followed by an "L," and therefore it matches. Sometimes, however, it is useful to make an operator nongreedy. This can be done by adding a ? character after the repetition operator. Modifying the above to, ".+?L" the .+? will now match "HE" rather than "HEL" since it has been placed in a nongreedy state. The ? can be added to any repetition character: ??, *?, +?, {M,N}?.

One very common thing to do is to check for things such as, a letter, or a digit. Rather than having to do, for example, "[0123456789]", the bracket operator supports ranges. Ranges work by specifying the beginning and ending point with a - between them. Therefore, a more simplistic way to test for a digit is to simply do "[0-9]". The same thing can be used on letters, or in fact, any range of ASCII values. If you want to match a letter, simply do "[a-z]" since Unreal is case insensitive, this will match all letters. You can also include multiple ranges in the same expression. To match a letter or a number, "[0-9a-z]". One complication that this creates is that the - is a special character in a bracket expression. To have it match a literal -, the easiest way is to place it as either the first or last character in the expression. For example, "[0-9-]" matches a digit or a -.

To make things even more simple, there are several "character classes" that may be used within a bracket expression. These character classes eliminate the need to define certain ranges. Character classes are written by enclosing their name in :'s. For example, "[0-9]" could also be written as "[:isdigit:]". The list below shows all of the available character classes and what they do:

• alnum - alphanumeric characters
• alpha - alphabetic characters
• blank - blank characters
• cntrl - control characters
• digit - decimal digits (0 through 9)
• graph - all printable characters except space
• lower - lower-case letters
• print - printable characters including space
• punct - printable characters not space or alphanumeric
• space - white-space characters
• upper - upper case letters
• xdigit - hexadecimal digits

The last feature of the bracket expression is negation. Sometimes it is useful to say "anything except these characters." For example, if you want to check if the character is "not a letter," it is easier to list a-z and say "not these," than it is to list all the non-letters. Bracket expressions allow you to handle this through negation. You negate the expression by specifying a "^" as the first character. For example, "[^a-z]" would match any non-letter. As with the -, if you want to include a literal ^, do not place it in the first position, "[a-z^]". Also, to negate a character class, you must once again use nesting, "[^[:isdigit:]]" would match any non-digit.

The ^ character is referred to as the "left anchor." This character matches the beginning of a string. If you simply specify a regex such as "test", it will match, for example "this is a test" since that string contains "test." But, sometimes it is useful to ensure that the string actually starts with the pattern. This can be done with ^. For example "^test" means that the text must start with "test." Additionally, the $ character is the "right anchor." This character matches the end of the string. So if you were to do "^test$", then the string must be exactly the word "test."

Similar tests also exist for words. All of the other assertions are specified using a \ followed by a specific character. For example, to test for the beginning and ending of a word, you can use \< and \> respectively.

The remaining assertions all come with two forms, a positive and a negative. These assertions are listed below:

• \b - Word boundary
• \B - Non-word boundary
• \d - Digit character (equivalent to [[:digit:]])
• \D - Non-digit character (equivalent to [^[:digit:]])
• \s - Space character (equivalent to [[:space:]])
• \S - Non-space character (equivalent to [^[:space:]])
• \w - Word character (equivalent to [[:alnum:]_])
• \W - Non-word character (equivalent to [^[:alnum:]_])

Since you can only have 9 back references, this is the reason why the (?:) notation is useful. It allows you to create a subexpression without wasting a back reference. Additionally, since back reference information does not need to be saved, it is also faster. Because of this, non-back reference subexpressions should be used whenever back references are not needed.