Editing the /etc/sysctl.conf file

I dont think, there is a sysctl.conf file in OSX.
What works, is to make a startupscript in /Library/StartupItems.
There you can make the needed adjustments to the values. The Script will be executed at every start of the system.

Just use a plaintext editor like vi, emacs or pico (pico's probably the easiest to figure out) and put variable=value, one per line like:

net.inet.tcp.sendspace=4000000
net.inet.tcp.recvspace=4000000

CAUTION: make SURE that those values work OK before putting them in this file, otherwise the machine may not boot!

Roger

What is sysctl and what does it do?

Open up Terminal and type

man sysctl

It lets you read and set kernel parameters that alter kernel behavior and settings.

You get an Idea of how the structure of a startup script is made by looking into:
/System/Library/StartupItems

copy one of the simpler script from there to /Library/StartupItems and edit the names of the directories and files and the content.

Here is documentation availible:
http://developer.apple.com/cgi-bin/search.pl?q=StartupItems&site=default_collect ion

I dont think, there is a sysctl.conf file in OSX.
What works, is to make a startupscript in /Library/StartupItems.

hello nobody,

I don't think that a StartupItem is necessary.
take a look at /etc/rc around line 50-60:

51 if [ -f /etc/sysctl-macosxserver.conf ]; then

52 awk '{ if (!index($1, "#") && index($1, "=")) print $1 }' < /etc/sysctl-macosx server.conf | while read

53 do

54 sysctl -w ${REPLY}

55 done

56 fi

57 if [ -f /etc/sysctl.conf ]; then

58 awk '{ if (!index($1, "#") && index($1, "=")) print $1 }' < /etc/sysctl.conf | while read

59 do

60 sysctl -w ${REPLY}

61 done

62 fi


Best regards
Martin

Yes, thanks. I had read the man page before I asked the question.

Macmartin:
You are right !
Thanks for this information.

A startup script or a launchd item might have the advantage of beeing more compatible. It now happend several times, an OS upgrade did overwrite things like /etc/hosts, /etc/mail ...

I have been using TextEdit to edit the sysctl.conf, and it works fine.

Mind you, I am still in the process of working out the TCP parameters, and by no means am I an expert. Having said that, here is what works for me so far:

net.inet.tcp.delayed_ack=1
kern.ipc.maxsockbuf=2097152
kern.maxvnodes=17408
net.inet.ip.portrange.first=40000
net.inet.ip.portrange.hifirst=45000
net.inet.ip.portrange.hilast=65532
net.inet.ip.portrange.lowfirst=1022
net.inet.ip.portrange.lowlast=400
net.inet.tcp.recvspace=1048756
net.inet.tcp.sendspace=1048576
net.inet.tcp.rfc1323=0
net.inet.udp.maxdgram=57344
net.inet.udp.recvspace=84160
net.local.stream.recvspace=16000
net.local.stream.sendspace=16000

One of my help sources was www.speedguide.net

I also used www.speakeasy.net/speedtest/ to help check the connection as I tweaked the settings.

Some of the values seem ridiculously high, but they appear to work!

To make your sysctl file (if it isn't already there):

- paste the above settings into a plain text file
- save a copy to your account. Then (with admin access):
- place it in the invisible /private/etc folder which
resides in the HD's root directory

I hope this helps!

If you are going to have these settings:

net.inet.tcp.sendspace=4000000
net.inet.tcp.recvspace=4000000

You need to set your kern.ipc.maxsockbuf=8000000 because it needs to be at least the sum of send and rcv values.

If you don't, the network will not initiate and the Mac will hang during bootup... you don't want that, trust me!