I'm administering an ArcGIS Server 10.3 system which is located in a client hosting facility with rather strict security. One restriction is that no browser can be opened inside the enclave. As one can imagine this makes making changes in AGS a bit of a challenge. Now I've hit a wall when it comes to SoE extensions.
Is there any way to install an SoE extension without access to a browser?
Hmmm...While I haven't done this, I can say that I just uploaded a sample SOE to my GIS Server and then searched my Linux box for for the SOE filename.
First, using the browser drops the SOE into arcgis/server/usr/directories/arcgissystem/arcgisuploads/admin/<somestring>/soename.soe.
From there, it looks to be moved into arcgis/server/usr/config-store/extns/ and arcgis/server/usr/lib/ext/. I don't know what other magic might happen behind the scenes.
You COULD use some tool to do a POST with cURL or similar to https://server.domain.com/webadaptor/admin/uploads/upload
The POST body would look similar to:
Content-Disposition: form-data; name="itemFile"; filename="C:\path\to\soe\SampleRestSoe2.soe"
That's likely a better option than trying to manually drop the SOE in the directories mentioned above and hoping it works.