Welcome to ircu2.10.12, the Undernet IRC daemon

Version u2.10.12 of the Undernet ircd incorporates many new features
over its predecessor, and we feel that using it will make you very
happy indeed.

New features include:
  - A completely rewritten network event engine, which make full use
    of the asynchronous event engines available in FreeBSD (kqueue)
    and Solaris (/dev/poll), resulting in dramaticaly improved
  - New F: (feature) lines in ircd.conf, and the GET/SET commands allow
    many settings to be changed dynamically, rather than by with compile-
    time configuration.
  - The new "account" feature added to the P10 protocol, allows people to
    remain logged in to service bots (i.e., gnuworld) during a netsplit.
    This means people will not have to login again once the network rejoins.


Please see the INSTALL file for installation instructions, for hints on how
to best configure your OS for running ircu under high load, see the various
README.<platform> files.


This version of ircu will only work with servers that use the P10 protocol,
some of the new features will only work between ircu2.10.12 servers.


For platform-specific notes and hints, see the platform-specific
sections below.  These notes apply to servers that will serve large
numbers (thousands) of clients simultaneously.  If your server serves
a small amount of users, the defaults should work well enough.

 - Run an OS that supports an asynchronous network event engine; currently
   these are FreeBSD (kqueue), and Solaris (/dev/poll); possibly other BSDs
   will also support kqueue. This will have a dramatic effect on performance.
 - Make things as lean as possible: Make your server dedicated to ircu,
   disable anything that is not neccesary, and build a custom kernel (where
 - Tune kernel parameters as described in the platform-specific
   sections below.
 - With many clients connecting each second, ircu will be doing lots of DNS
   lookups. Make sure that the DNS server(s) in your /etc/resolv.conf are as
   close as possible, or run a local caching DNS server on your IRC server.


Many things can and will go horribly wrong when the clocks on the servers
on your network become (too far) out of sync. It is therefore highly
recommended that all servers run a version of ntpd that will keep their
clocks from going astray.


As per undernet-admins CFV-165, this server contains code that will,
by default, hide certain information from ordinary users. If you do
not want this, override the default "HIS" feature settings in your


For more information on this software, see the included documentation
in the doc/ directory, as well as

For general information on the Undernet, vist

Happy IRCing!


If you run Linux 2.6 or above (or 2.4 with appropriate patches), ircu
can use the epoll family of system calls for much more efficient
checks of which connections are active.  Most pre-epoll systems will
use 100% CPU with 2000 clients; with epoll, a server may use only a
few percent of CPU with the same load.

To handle that many connections, the ircd must be started with a high
enough file descriptor resource.  Check your distribution's docs on
how to set the global and per-user limits according to your expected


When running on FreeBSD, ircu can make use of the kqueue() event engine, which
results in much improved performance over the old poll()-based method. kqueue
is included in the more recent 4.x releases of FreeBSD.

In order for ircu to be able to serve many clients simultaneously, you need
to increase the maximum allowable number of open files in the system. To do
this, add commands such as the following during your system's boot sequence:

sysctl -w kern.maxfiles=16384
sysctl -w kern.maxfilesperproc=16384

Unless you will be serving thousands of clients simultaneously, you will not
need to do the following, unless of course you just can't stand having a
system that is not optimized to its limits :)

Build a custom kernel: Make your kernel as lean as possible by removing all
drivers and options you will not need. The following parameters will affect
performance, they are listed with suggested values only. For more information
on what they do exactly, see FreeBSD's documentation.

maxusers        2048
options         NMBCLUSTERS=65535
options         ICMP_BANDLIM

Also, you may wish to run the following at system startup (from /etc/rc.local,
or whichever other method you prefer):

sysctl -w net.inet.tcp.rfc1323=1
sysctl -w net.inet.tcp.delayed_ack=0
sysctl -w net.inet.tcp.restrict_rst=1
sysctl -w kern.ipc.maxsockbuf=2097152
sysctl -w kern.ipc.somaxconn=2048

Created by Sengaia <>, July 20 2002.


When running on Solaris, ircu can make use of the /dev/poll event engine, which
results in much improved performance over the old poll()-based method. Solaris
versions 8 and 9 include /dev/poll out of the box, for Solaris 7 you will have
to grab and install Patch-ID 106541-21.

In order to increase the number of clients ircu can handle, add lines such as
the following to /etc/system:

* set hard limit on file descriptors
set rlim_fd_max = 16384
* set soft limit on file descriptors
set rlim_fd_cur = 8192

For more useful hints see

Created by Sengaia <> on July 20, 2002.