Firstly, according to Jamie Cameron (the dev of Webmin - see here) they will be releasing a version with a cert signed by a CA (which will resolve this issue). But unless you take matters into your own hands, I'm not sure when this update will make it into TKL (once it has been released).
As also mentioned (in the maillist thread that I linked to above) Java can be adjusted (i.e. by relaxing security) to work around this. Not ideal but one way to get around it...
Another option is to use an SFTP/SCP client (e.g. Filezilla, WinSCP, etc) to manage your server's filesystem.
Some thoughts...
Firstly, according to Jamie Cameron (the dev of Webmin - see here) they will be releasing a version with a cert signed by a CA (which will resolve this issue). But unless you take matters into your own hands, I'm not sure when this update will make it into TKL (once it has been released).
As also mentioned (in the maillist thread that I linked to above) Java can be adjusted (i.e. by relaxing security) to work around this. Not ideal but one way to get around it...
Another option is to use an SFTP/SCP client (e.g. Filezilla, WinSCP, etc) to manage your server's filesystem.