How do I restart sshd on my Linux/Unix system

After you have changed your configuration on your remote Unix/linux server you must restart your ssh service. The easiest way to do this is to simply restart your Unix machine. This is not always possible however.
To restart sshd without restarting your whole system, enter the following command as root

RedHat and Fedora Core Linux

/sbin/service sshd restart

Suse linux

/etc/rc.d/sshd restart

Debian/Ubuntu

/etc/init.d/sshd restart

Solaris 9 and below

/etc/init.d/sshd stop
/etc/init.d/sshd start

Solaris 10

svcadm disable ssh
svcadm enable ssh

AIX

stopsrc -s sshd
startsrc -s sshd

HP-UX

/sbin/init.d/secsh stop
/sbin/init.d/secsh start

Reference: http://www.starnet.com/xwin32kb/restart_sshd