OpenLDAP server daemon slapd Installation in Ubuntu
First, install the OpenLDAP server daemon slapd and ldap-utils, a package containing LDAP management utilities:
sudo apt-get install slapd ldap-utils
By default slapd is configured with minimal options needed to run the slapd daemon.
The configuration example in the following sections will match the domain name of the server. For example, if the machine’s Fully Qualified Domain Name (FQDN) is ldap.example.com, the default suffix will be dc=example,dc=com.
Populating LDAP
OpenLDAP uses a separate directory which contains the cn=config Directory Information Tree (DIT). The cn=config DIT is used to dynamically configure the slapd daemon, allowing the modification of schema definitions, indexes, ACLs, etc without stopping the service.
Tags: Daemon, Installation, OpenLDAP, server, slapd, Ubuntu
slapd - Stand-alone LDAP Daemon
LDAP (Lightweight Directory Access Protocol) is a proposed open standard for accessing global or local directory services over a network and/or the Internet. A directory, in this sense, is very much like a phone book. LDAP can handle other information, but at present it is typically used to associate names with phone numbers and email addresses. LDAP directories are designed to support a high volume of queries, but the data stored in the directory doesn’t change very often.
OpenLDAP includes slapd (a stand-alone LDAP server), slurpd (a stand-alone LDAP replication server), libraries implementing the LDAP protocol, utilities, tools, and sample clients.
Slapd is the stand-alone LDAP daemon. It listens for LDAP connections on any number of ports (default 389), responding to the LDAP operations it receives over these connections. slapd is typically invoked at boot time, usually out of /etc/rc.local.
Tags: Daemon, LDAP, slapd, Stand-alone
renice — alter priority of running processes
Renice alters the scheduling priority of one or more running processes. The following who parameters are interpreted as process ID’s, process group ID’s, or user names. a process group causes all processes in the process group to have their scheduling priority altered. a user causes all processes owned by the user to have their scheduling priority altered. By default, the processes to be affected are specified by their process ID’s.
For example,
renice +1 987 -u daemon root -p 32
would change the priority of process ID’s 987 and 32, and all processes owned by users daemon and root.
Users other than the super-user may only alter the priority of processes they own, and can only monotonically increase their “nice value” within the range 0 to PRIO_MAX (20). (This prevents overriding administrative fiats.) The super-user may alter the priority of any process and set the priority to any value in the range PRIO_MIN (?20) to PRIO_MAX. Useful priorities are: 20 (the affected processes will run only when nothing else in the system wants to), 0 (the “base” scheduling priority), anything negative (to make things go very fast).
Tags: priority, processes, renice, Running
Downloading and using kernel source on Ubuntu
There may come a time when you need the kernel source code, usually to build kernel headers, compile a module etc. To work with the kernel source once you have it, you’ll want some development tools installed on your server.
sudo aptitude update
sudo aptitude install build-essential
To check the version right on the server. Just run:
root@laptop:~# uname -r
2.6.28-11-generic
Searching for kernel source.
# apt-cache search linux-source
linux-ports-source-2.6.28 - Linux kernel source for version 2.6.28 with Ubuntu patches
linux-source - Linux kernel source with Ubuntu patches
linux-source-2.6.28 - Linux kernel source for version 2.6.28 with Ubuntu patches
Tags: Downloading, Kernel, Source, Ubuntu
When the kernel loads, it immediately initializes and configures the computer’s memory. Next it configures the various hardware attached to the system, including all processors and I/O subsystems, as well as any storage devices. It then looks for the compressed initrd image in a predetermined location in memory, decompresses it, mounts it, and loads all necessary drivers. Next it initializes file system-related virtual devices, such as LVM or software RAID before unmounting the initrd disk image and freeing up all the memory it once occupied.
After the kernel has initialized all the devices on the system, it creates a root device, mounts the root partition read-only, and frees unused memory.
At this point, with the kernel loaded into memory and operational. However, with no user applications to give the user the ability to provide meaningful input to the system, not much can be done with it.
To set up the user environment, the kernel starts the /sbin/init command.
Tags: Kernel, linux
