Why can't the SCTP module parameters 'rto_alpha_exp_divisor' and 'rto_beta_exp_divisor' be modified in RHEL6?

Issue

• In RHEL6, the SCTP parameters rto_alpha_exp_divisor and rto_beta_exp_divisor remain read-only under /proc/sys/net/sctp:

# ll  /proc/sys/net/sctp/rto_[ab]*
-r--r--r-- 1 root root 0 Mar 26 11:07 /proc/sys/net/sctp/rto_alpha_exp_divisor
-r--r--r-- 1 root root 0 Mar 26 11:07 /proc/sys/net/sctp/rto_beta_exp_divisor
# 

• Changing the values using the command sysctl and via the file /etc/sysctl.conf fails. Also trying to echo new values fails:

# cat rto_alpha_exp_divisor
3
# echo 10 > rto_alpha_exp_divisor
bash: rto_alpha_exp_divisor: Permission denied
# echo 10 > rto_beta_exp_divisor
bash: rto_beta_exp_divisor: Permission denied