I want to inventory the hardware of my Linux systems using only ssh on the client end

Without installing any new software on the remote systems, you can grab a raw snapshot of the remote machine's state with:

lspci > /tmp/`hostname`-lspci
tar -czvf `hostname`-proc-snapshot.tar.gz /proc /tmp/`hostname`-lspci --exclude=/proc/kcore

Then scp the tar archive from the remote server. This will get you: cpuinfo, meminfo, partitions, etc. Add more commands and temporary files for any additional information you may need (logical volumes, raid status, etc.)

As a minor bonus, you get an inventory of running processes on the remote machine at that instant.

Maybe try http://www.cfg2html.com/ it's just one bash script that outputs to html, which you can upload/download to a central directory. However it's just the output from commands so it's pretty hard to put it in a structured format like sql/xml.

You could install Spiceworks in a windows vm. It only uses ssh to inventory linux hosts.

Depending on if you have Python2 installed on your systems, you could also use Ansible.

ansible -m setup ${hostname}

This will output a nice JSON which includes CPU/RAM/HDD/Network and software configuration. Read the documentation for more information.

lshw command gives you a lot of hardware information and can output it in HTML or XML format...

If lshw is installed on the machines, you can use that, but it doesn't come pre-installed on Redhat and it's derivatives. There are RPM's out there for it, and you may be able to extract the required files from an RPM, SCP them to the machines, create a few symbolic links (most likely a link from /usr/sbin/lshw to the tmp location of the file, and from /usr/share/lshw to the tmp location of the folder) then you run lshw and remove the symbolic links afterwards. That is assuming you have root/sudo access ...

Copy hw-probe and hwinfo utilities to the temp directory on the server and run locally w/o installing anything. Just done this for one of my servers.

Example for CentOS 6:

1. Connect to server

   ssh user@server
   

2. Create a temp directory

   mkdir -p /tmp/hw-inventory
   cd /tmp/hw-inventory
   

3. Download proper hwinfo and libx86emu rpm binary packages

   wget http://mirror.ghettoforge.org/distributions/gf/el/6/gf/x86_64/hwinfo-20.2-1.gf.el6.x86_64.rpm
   wget http://mirror.ghettoforge.org/distributions/gf/el/6/gf/x86_64/libx86emu-1.1-1.gf.el6.x86_64.rpm
   

4. Extract them

   rpm2cpio hwinfo-21.47-4.1.x86_64.rpm | cpio -id
   rpm2cpio libx86emu-1.1-1.gf.el6.x86_64.rpm | cpio -id
   

5. Get latest hw-probe script

   wget https://github.com/linuxhw/hw-probe/archive/master.zip
   unzip master.zip
   

6. Create a probe

   sudo perl hw-probe-master/hw-probe.pl -all -upload -hwinfo-path ./usr/sbin/hwinfo
   

7. Clear local temp directory

   cd ~/
   rm -fr /tmp/hw-inventory /root/HW_PROBE
   

The utility will return a permanent url to view collected hardware details and hardware related logs (like this).

I've just added an option -hwinfo-path to hw-probe:master to simplify your use case.

If you'd like to inventory many computers, then please see https://github.com/linuxhw/hw-probe#inventory.

I'm the author of the hw-probe project, feel free to ask any questions in the comments to this answer.