My distro is FC2 and I have following lines in /etc/rc.d/rc.local

echo 1 > /proc/sys/net/ipv4/tcp_timestamps
echo 26136 > /proc/sys/net/core/rmem_max
echo "11616 20328 26136" > /proc/sys/net/ipv4/tcp_rmem
echo 26136 > /proc/sys/net/core/wmem_max
echo "11616 20328 26136" > /proc/sys/net/ipv4/tcp_wmem
echo 20328 > /proc/sys/net/core/rmem_default
echo 20328 > /proc/sys/net/core/wmem_default
echo 1 > /proc/sys/net/ipv4/tcp_sack

But somehow tcp_sack can't be set 1 when rebooing.
(other values seems to be modified correctly)
What am I doing wrong? I thought it could be file access permission matter and did:

chmod ogu+w /proc/sys/net/ipv4/tcp_sack

but when I reboot, the write permission for write is again removed for 'others' and 'users'
and tcp_sack is still set 0.

Hope someone can help me out....

In addition to the above question:
if I do the following as root after logon:

echo 1 > /proc/sys/net/ipv4/tcp_sack

the tcp_sack is set 1. Any help is appreciated...