On a FreeBSD system (8.1), I am looking for instructions on how to check the running version of OpenSSH and also instructions on the best way to download install an update of OpenSSH
sshd -V or
ssh -V and they'll return the version and usage information.
Note: These are capital "V" now, when I originally wrote this answer they were lower case.
There's a dozen ways to upgrade.
pkg-add -r openssh-portable
cd /usr/ports/security/openssh && make install clean
- part of the makeworld/buildworld process
- and the list goes on...
I'm not aware of any issues with the 5.2p1 version that shipped with 8.1-RELEASE. I have seen hoax e-mails flying around for over a year now announcing the imminent release of a zero day hack (note that it's been a year and a half since release, so 'zero' day was a heck of a long time ago).
telnet localhost 22
Why do you want to upgrade OpenSSH? It's part of the core system and is usually upgraded with the system.
If that prints /usr/sbin/sshd, then it's probably installed as a package. In that case, you can check the installed version using:
pkg_info | grep ssh
pkg_info -W `type sshd`
And I think you update it using:
pkg_add -r openssh-portable
but read the FreeBSD Guide to the Packages System first, because I haven't done that in a long time and it might have changed.
prints /usr/local/sbin/sshd, then it's probably installed as a port.
Read up on how to upgrade it in the Guide to Using the Ports System. The port name is security/openssh-portable, i.e. /usr/ports/security/openssh-portable.
How to find openssh version on a Linux or Unix-like system?
The syntax is as follows to find openssh version on a CentOS/RHEL/SL:
# yum list installed openssh\*
The syntax is as follows to find openssh version on a Debian/Ubuntu Linux:
$ dpkg --list | grep openssh ### OR ### $ dpkg --list openssh\*