Failing to export to Piwigo. How to debug?

[Felix Kloss]

Hello,

I recently set up a self-hosted Piwigo instance and would like to upload 
pictures directly from digiKam.  It worked for one or two pictures in 
the beginning but now always fails with this error:

 > Failed to upload media into remote Piwigo. Error transferring
 > https://photos.luator.de/ws.php - server replied: Forbidden

I checked the server logs and found the following:

When "Resize photos before uploading" is enabled:

ModSecurity: [file 
"/etc/httpd/conf/modsecurity.d/rules/tortix/modsec/10_asl_rules.conf"] 
[line "389"] [id "340029"] [rev "37"] [msg "Atomicorp.com WAF Rules: 
Attack Blocked - command in REQUEST_URI or Argument"] [data "/nc "] 
[severity "CRITICAL"] Access denied with code 403 (phase 2). Pattern 
match "(?:;|/|\\\\| 
)(?:\\\\b(?:cat|ls|perl|uname|pwd|cp|tclsh8?|cpp|f(?:etch|tp)|python|chown|rm|ping|rsync|rdiff-backup|scp|(?:w|ftp)get|curl|links|g\\\\+\\\\+|ch(?:grp|own)|passwd|r?(?:b|d)ash|t?c?sh|telnet|clang|nc)\\\\b 
|\\\\b(?:sleep|benchmark)\\\\b \\\\(? ?[0-9]|power ..." at ARGS:data. 
[hostname "photos.luator.de"] [uri "/ws.php"] [unique_id 
"ZEFFshFAvrfOIzhECOZbXwAAABc"]

I don't know anything about ModSecurity but found this description of 
the error: 
https://docs.atomicorp.com/rules/waf/10_asl_rules.conf.html#waf-rule-id-340029

Interestingly, if I disable the resizing before upload, I get a 
different error (something about spam, which doesn't make sense to me):

2023-04-20 16:13:06	Error	88.130.216.72	[client 88.130.216.72] 
ModSecurity: [file 
"/etc/httpd/conf/modsecurity.d/rules/tortix/modsec/30_asl_antispam.conf"] 
[line "213"] [id "300051"] [rev "9"] [msg "Atomicorp.com WAF AntiSpam 
Rules: Possible Spam: General"] [data " 732951 found within ARGS:data: 
gkpwnn8jkuo4tftwvxh+g2b5nmgptu+ljjvjrafisyxhmghy4ywqufbnib2iju2wj27c9sxgegolgcgnc3vpvbomaohifjjmstem97cgmguv5koqiy0ot10wp6amljtj6ws+5xzzhq1+erh4thntabmteeuf0a13h2jdwyc4ybsa8daitfvr8tlk0fmzojurisqmamm//agtwed7jtgfry4q40zdonz46euyxww4odjeub03j9o2k7k0myssz/lulgrttcbh1udrcgrqkhz1bnj5wufjyphsvheznsyp+xaiadwf+ik4yge1pccr1bdlqgykwye0qkia5pi6fzkomomnqotdpen+yjtytvpgxtizwcr8ybhb5op6snk15vrh1nerkfxjjyikbcbwlu1iqgst1iiuwkzrg+5n3kb73spuptxirlws0cw1ikrfhb3kbog2wisdgovl5tbptbgloj5pzliay..."] 
[severity "WARNING"] Access denied with code 403 (phase 2). Pattern 
match "(?:magazine[ -_.,\\"\\\\'\\\\|]?(?:finder|netfirms)|rolex[ 
-_.,\\"\\\\'\\\\|]|z0rder|well-fargo|phvonline|weight-watcher|virility[ 
-_.,\\"\\\\'\\\\|]pills|squirrelht|sams-club-online|nexium-online|levaquin-500|golden-coins|gmac-mortgage-corp|enlarge(ment)?pi 
[hostname "photos.luator.de"] [uri "/ws.php"] [unique_id 
"ZEFIcBFAvrfOIzhECOZgtAAAADs"]

Any idea what is causing this and if there is a way for me to fix it? 
Any hint on how I may debug this, would be very welcome.  For example, 
is there a log somewhere, where I can see the exact request that digiKam 
sends to the server?

I already posted the question on pixls.us 
(https://discuss.pixls.us/t/failing-to-export-to-piwigo/36745) and a 
user there said that on piwigo.com it is working for them, so likely it 
has to do with the configuration of my server (which is just a very 
simple web hosting package, so probably I can't change that config...). 
Anyway, I also tested the export to Piwigo in darktable and there it is 
working, so I still have some hope that there is something I can do to 
make it work with digiKam as well.

In case it matters: I'm using the digiKam 8.0.0 AppImage on Kubuntu 22.04.

Best,
Felix