Ubuntu Server, LAMP stack, freshly self-installed WordPress.

Apparently I can't use `direct` filesystem access method because files are owned by different owners (WP core unpacked by me and files WP creates by `www-data`).

I tried my credentials for `ftp` method, but either something goes wrong or there is simply no FTP server installed in stack.

Googled up suggestion to install `libssh2-php` and use `ssh` method. Filling my credentials (except keys, no idea what to put there) it worked for deleting plugins, but fails to install new ones with following error:

```
Downloading install package from http://downloads.wordpress.org/plugin/serverbuddy-by-pluginbuddy.0.1.6.zip…

Unpacking the package…

Could not copy file. /var/www/wp-content/upgrade/serverbuddy-by-pluginbuddy.tmp/

```

I am little lost which method to poke. Should I try to tweak and enforce `direct`? Or how to fix `ssh`? Or just install some ftp server?