Informix Dynamic Server V10 . . . Extended Functionality for Modern Business

Chapter 1. IDS essentials 31

second session. If during the waiting period, an attacker launches an attack in

a loop mode, a flood of attacks can be received on the connection.

To reduce the risk of denial of service attacks IDS provides multiple listener

threads (listen_authenticate) to handle connections and imposes limits on the

availability of the listener VP for incomplete connections. Two new

configuration parameters can be used to customize this feature:

LISTEN_TIMEOUT

Sets the incomplete connection time-out period (in seconds). This is the

number of seconds the server waits for the connection. The default value of

LISTEN_TIMEOUT parameter is 10.

MAX_INCOMPLETE_CONNECTION

You can restrict the number of incomplete requests for the connection using

MAX_INCOMPLETE_CONNECTION parameter. When the maximum value

is reached, an error message stating that server might be under Denial of

Service attack is written in the online message log file. The default value of

the MAX_INCOMPLETE_CONNECTION parameter is 1024.

1.3.3 Administration and usability

In this section, we provide a brief overview of the administration and usability

features of IDS V10.

 Single User Mode

Single user is an intermediate mode between quiescent mode and online

mode. This is an administrator mode which only allows user informix to

connect and perform any required maintenance, including the task requiring

the execution of SQL and DDL statements. You can set this mode using the -j

flag of the oninit and the onmode commands. The oninit -j command brings

the server from offline to single user mode and onmode -j brings the server

from online to single user mode. The server makes an entry in the message

log file whenever it enters and exits the single user mode. Figure 1-9 shows

an example of using onmode command to set the single user mode.

Figure 1-9 The onmode -j example

32 Informix Dynamic Server V10 . . . Extended Functionality for Modern Business

 Renaming Dbspaces

The need to rename the standard dbspaces might arise if you are

reorganizing the data in an existing dbspace. You can rename a previously

defined dbspace if you are user informix or have DBA privileges, and the

database server is in quiescent mode. The rename dbspace operation only

changes the dbspace name, it does not reorganize the data. It updates the

dbspace name in all the places where dbspace name is stored, such as

reserved pages on disk, system catalogs, the ONCONFIG file and in memory

data structures.You can also use onspaces command to rename the dbspace.

Here are some restrictions when using the rename dbspace feature:

– You cannot rename the critical spaces such as rootdbspace and space

containing physical logs and logical logs.

– You cannot rename a dbspace with down chunks.

– You cannot rename spaces with onmonitor command.

You must take a level 0 archive of the renamed space and root dbspace after

rename operation. Figure 1-10 shows the example of using onspaces

command to rename dbspace.

Figure 1-10 Renaming dbspace using the onspaces command

 Ontape use of STDIO

If you are using ontape to backup and restore data, you can now use

standard I/O instead of a tape device or disk file. This feature enables

pipe-based remote backups/restores such as might be done in HDR or to a

UNIX utility such as CPIO, TAR, or COMPRESS or to disk with a specific

filename other than that used by L/TAPEDEV. You can set this by setting the

value of configuration parameter TAPEDEV to STDIO. Refer to 9.3.1, “Ontape

to STDIO” on page 274 for more detail.