Fritzbox Fritz!Box AVM SSL Letsencrypt automatically update

fritzbox-cert-update.sh

#!/bin/bash
## this little Gist is for Copy the Letsencrypt Cert from an Linux machine (e.g. Raspberry PI or Synology NAS)
## to the router (Fritzbox).
## It is usefull to be able to speak to the Router over DDNS without any Cert issue in the Browser.
## thanks to https://gist.github.com/mahowi for the perfect Idea
## put it in /etc/letsencrypt/renewal-hooks/post so it gets run after every renewal.
## since Fritz OS 7.25 it is needed to select a Username, from a security point of view 
## it is always a good idea to have a non default user name. And as normaly a Fritz Box
## is connected to the Internet, the prefered method should be WITH Username.


# parameters
USERNAME="needed since Fritz OS 7.25"
PASSWORD="fritzbox-password"
CERTPATH="path to cert eg  /etc/letsencrypt/live/domain.tld/"
CERTPASSWORD="cert password if needed"
HOST=http://fritz.box

# make and secure a temporary file
TMP="$(mktemp -t XXXXXX)"
chmod 600 $TMP

# login to the box and get a valid SID
CHALLENGE=`wget -q -O - $HOST/login_sid.lua | sed -e 's/^.*<Challenge>//' -e 's/<\/Challenge>.*$//'`
HASH="`echo -n $CHALLENGE-$PASSWORD | iconv -f ASCII -t UTF16LE |md5sum|awk '{print $1}'`"
SID=`wget -q -O - "$HOST/login_sid.lua?sid=0000000000000000&username=$USERNAME&response=$CHALLENGE-$HASH"| sed -e 's/^.*<SID>//' -e 's/<\/SID>.*$//'`

# generate our upload request
BOUNDARY="---------------------------"`date +%Y%m%d%H%M%S`
printf -- "--$BOUNDARY\r\n" >> $TMP
printf "Content-Disposition: form-data; name=\"sid\"\r\n\r\n$SID\r\n" >> $TMP
printf -- "--$BOUNDARY\r\n" >> $TMP
printf "Content-Disposition: form-data; name=\"BoxCertPassword\"\r\n\r\n$CERTPASSWORD\r\n" >> $TMP
printf -- "--$BOUNDARY\r\n" >> $TMP
printf "Content-Disposition: form-data; name=\"BoxCertImportFile\"; filename=\"BoxCert.pem\"\r\n" >> $TMP
printf "Content-Type: application/octet-stream\r\n\r\n" >> $TMP
cat $CERTPATH/privkey.pem >> $TMP
cat $CERTPATH/fullchain.pem >> $TMP
printf "\r\n" >> $TMP
printf -- "--$BOUNDARY--" >> $TMP

# upload the certificate to the box
wget -q -O - $HOST/cgi-bin/firmwarecfg --header="Content-type: multipart/form-data boundary=$BOUNDARY" --post-file $TMP | grep SSL

# clean up
rm -f $TMP

@mbo77 What a pity. But thanks for sharing the answer. At least I'll list the Fritz!Repeater 1200 AX with 7.57 as unsupported. Unfortunately there is no easy way to get the product name and the OS version from a fritzbox to check it.

Hello,
I want to share my experience.
The script worked well. At a certain point it looks not working properly: no error prompted and no certificate imported.
After troubleshooting it I've discovered the issue was related to letsencrypt that changed from rsa to ecdsa. I replaced in the letsencrypt configuration file as below
#key_type = ecdsa
key_type = rsa
And now is working well back.
hope my experience will help you.

(tested with fritz7590 and 7530ax both version 7.57)