Allow block

Allow blocks specify who may connect to this server and what class to put the user in. You can have multiple allow blocks.

Syntax[edit]

allow {
        mask <mask>;
        class <connection-class>;
        maxperip <max-connections-per-ip-locally>;

        /* All the rest is optional: */
        global-maxperip <max-connections-per-ip-globally>;
        password <connection-password> { <auth-type>; }; /* OPTIONAL */
        ipv6-clone-mask <number-of-bits>; /* OPTIONAL */
        redirect-server <server-to-forward-to>; /* OPTIONAL */
        redirect-port <port-to-forward-to>; /* OPTIONAL */
        options {
            <option>;
            <option>;
            ...
        };
};

Do you have multiple allow blocks? Then note that they will be read upside down, so you need specific host/ip allow blocks AFTER your general *@* allow blocks.

If a client does not match any allow block then the client is rejected with the message from set::reject-message.

required items[edit]

mask[edit]

You must specify a mask such as mask *;. Advanced users may wish to look at Mask item to see a lot more options that can be used for masks, such as lists, negative matching, matching SASL users, certificate fingerprints, etc.

class[edit]

Specifies the class name that connections using this allow block will be placed into.

maxperip[edit]

With maxperip you specify how many local connections may come from each IP. For example maxperip 4; means that only 4 clients may connect per-IP to this server.

global-maxperip[edit]

This specifies the global maximum number of connections from each IP (network-wide). If you don't have this, then it will default to maxperip+1.

optional items[edit]

password[edit]

The server password or another authentication method that the user authenticates with.

There are two possible behaviors for password control:

optional password to get extra rights[edit]

The default behavior is, if the password is incorrect, to continue matching next allow block:

allow { mask *; class clients; maxperip 2; }
allow { mask *; password "iwantmore"; class clients; maxperip 10; }

If a user connects with the password iwantmore then they will get a maxperip of 10. If the user does not connect with that password (either wrong or no password) then the user will get a maxperip of 2.

mandatory password[edit]

On the other hand, you may want to use passwords to keep other users out. In this case you need to use allow::options::reject-on-auth-failure as described below:

allow { mask *; class clients; maxperip 2; }
allow { mask *@*.nl; password "tehdutch"; class clients; maxperip 2; options { reject-on-auth-failure; } }

In this case anyone with a hostname of *.nl must provide the password tehdutch. If they don't, they will be rejected access and cannot connect to the server.

ipv6-clone-mask[edit]

This option controls clone detection and is basically IPv6's variant of maxperip. If you don't have IPv6 enabled then this option has no effect. If two clients connect from different IPv6 addresses but only the last few bits are different, there is almost a guarantee that both clients are really one person. This option only affects the enforcement of allow::maxperip. For example, if you set this option to 128, then each IPv6 address will be considered unique. Because of current IP allocation policies, it is recommended that your most general allow block use a value of 64. Since 64 is already the default in set::default-ipv6-clone-mask you probably don't need to change this.

redirect-server & redirect-port[edit]

When the class is full (class::maxclients) we will redirect new users to this server. This requires support from the IRC client side, popular clients like mIRC support this but this feature is broken in case of SSL/TLS so is likely of little use in the modern world.

redirect-server specifies the server name and redirect-port the port (6667 by default).

options[edit]

One option gives you additional flexibility for matching:

tls: Only match if this client is connected via SSL/TLS.

Meaning, if this doesn't match, UnrealIRCd jumps to next allow block.

There are also two other options that don't have anything to do with matching but will affect the user/host:

useip: Always display IP instead of hostname.
noident: Don't use ident but use username specified by client.

And, finally, there's one special option that is rarely used:

reject-on-auth-failure: Reject the user if the password is not provided or does not match. See also the password option above for a longer explanation.

Example[edit]

Example 1: generic block and specific block[edit]

allow {
	mask *;
	class clients;
	maxperip 3;
};

allow {
	mask 1.2.3.*;
	class clients;
	maxperip 25;
};

Example 2: extended matching[edit]

NOTE: This options is available in UnrealIRCd 6.0.4 and later. If you are using an older version then see example 3 instead

allow {
	mask *;
	class clients;
	maxperip 3;
};

allow {
	mask {
                mask { 1.2.3.0/24; }
                account { TrustedUser1; TrustedUser2; }
                certfp { "1234567890abcdef1234567890abcdef123456"; } /* Add more than one certfp: "secondone"; "thirdone";  */
        }
	class clients;
	maxperip 25;
};

This will:

Grant the high maxperip 25 to users matching any of the following criteria (OR!):
- Any user in the IP range 1.2.3.0/24, OR
- Users identified to services via SASL with the account name TrustedUser1 or TrustedUser2, OR
- A user which uses certificate fingerprint (sha256) 1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef
All the other clients get a maxperip 3

Example 3: extended matching (before UnrealIRCd 6.0.4)[edit]

allow {
	mask *;
	class clients;
	maxperip 3;
};

allow {
	mask 1.2.3.*;
	class clients;
	maxperip 25;
};

allow {
	mask { ~a:TrustedUser1; ~a:TrustedUser2; }
	class clients;
	maxperip 25;
};