如何限制ssh 和telnet登陆的最大链接数，具体操作过程和解释如下：
1）备份/etc/xinetd.conf
Test:/ #cp /etc/xinetd.conf /etc/xinetd.conf.bak
Test:/ # id
uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel) context=root:system_r:unconfined_t

2）修改/etc/xinetd.conf文件中的instances参数（红色部分）
Test:/ # cat /etc/xinetd.conf
#
# xinetd.conf
#
# Copyright (c) 1998-2001 SuSE GmbH Nuernberg, Germany.
# Copyright (c) 2002 SuSE Linux AG, Nuernberg, Germany.
#

defaults
{
 log_type = FILE /var/log/xinetd.log
 log_on_success = HOST EXIT DURATION
 log_on_failure = HOST ATTEMPT
# only_from = localhost
 instances = 30
 cps = 50 10

#
# The specification of an interface is interesting, if we are on a firewall.
# For example, if you only want to provide services from an internal
# network interface, you may specify your internal interfaces IP-Address.
#
# interface = 127.0.0.1
}
includedir /etc/xinetd.d
修改instances参数为实际需要值即可。