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Hi.. I'm using the webdav module that's included in the lighttpd server, running on Linux. Here's the server log for the Textastic access: the "401" is caused by the basic authentication:

xxx.xxx.xxx.xxx:80 - - [01/Sep/2011:15:26:48 +0100] "PROPFIND /DAV/ HTTP/1.1" 401 351 "-" "Textastic/34 CFNetwork/485.13.9 Darwin/11.0.0" "-"
xxx.xxx.xxx.xxx:80 - myuser  [01/Sep/2011:15:26:49 +0100] "PROPFIND /DAV/ HTTP/1.1" 207 387 "-" "Textastic/34 CFNetwork/485.13.9 Darwin/11.0.0" "-"

and here's Keynote accessing the same area:

xxx.xxx.xxx.xxx:80 - - [01/Sep/2011:15:30:15 +0100] "PROPFIND /DAV HTTP/1.1" 207 670 "-" "iWorkHTTPKit (iPad; iPhone OS 4.3.5; en_GB) Keynote/336" "-"
xxx.xxx.xxx.xxx:80 - - [01/Sep/2011:15:30:17 +0100] "PROPFIND /DAV HTTP/1.1" 207 1731 "-" "iWorkHTTPKit (iPad; iPhone OS 4.3.5; en_GB) Keynote/336" "-"
xxx.xxx.xxx.xxx:80 - - [01/Sep/2011:15:30:36 +0100] "PROPFIND /DAV/myuser HTTP/1.1" 401 351 "-" "iWorkHTTPKit (iPad; iPhone OS 4.3.5; en_GB) Keynote/336" "-"
xxx.xxx.xxx.xxx:80 - myuser [01/Sep/2011:15:30:39 +0100] "PROPFIND /DAV/myuser HTTP/1.1" 207 2931 "-" "iWorkHTTPKit (iPad; iPhone OS 4.3.5; en_GB) Keynote/336" "-"