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74 lines
1.5 KiB
74 lines
1.5 KiB
#!/bin/sh |
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# |
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# SPDX-FileCopyrightText: 2003 Theodore Ts'o <tytso@alum.mit.edu> |
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# SPDX-License-Identifier: GPL-2.0-or-later |
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# |
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# This script will extract the necessary certificate from the IMAP server |
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# It assumes that an attacker isn't trying to spoof you when you connect |
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# to the IMAP server! You're better off downloading the certificate |
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# from a trusted source. |
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# |
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usage() { |
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echo "Usage: $0 [-s] <host>" >&2 |
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echo " -s Use IMAP+STARTTLS (port 143) instead of IMAPS (port 993)" >&2 |
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exit 1 |
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} |
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STARTTLS=false |
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while getopts "s" opt; do |
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case $opt in |
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s) STARTTLS=true ;; |
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*) usage ;; |
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esac |
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done |
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shift `expr $OPTIND - 1` |
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if [ $# -ne 1 ]; then |
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usage |
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fi |
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HOST=$1 |
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seed=`date '+%s'` |
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try=0 |
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while :; do |
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TMPDIR=/tmp/get-cert.$$.$seed |
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mkdir $TMPDIR 2> /dev/null && break |
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if [ $try = 1000 ]; then |
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echo "Cannot create temporary directory." >&2 |
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exit 1 |
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fi |
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try=`expr $try + 1` |
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seed=`expr \( \( $seed \* 1103515245 \) + 12345 \) % 2147483648` |
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done |
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TMPFILE=$TMPDIR/get-cert |
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ERRFILE=$TMPDIR/get-cert-err |
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CERTFILE=$TMPDIR/cert |
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if $STARTTLS; then |
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FLAGS="-starttls imap" |
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PORT=143 |
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else |
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FLAGS= |
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PORT=993 |
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fi |
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echo QUIT | openssl s_client $FLAGS -connect $HOST:$PORT -showcerts \ |
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> $TMPFILE 2> $ERRFILE |
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sed -e '1,/^-----BEGIN CERTIFICATE-----/d' \ |
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-e '/^-----END CERTIFICATE-----/,$d' < $TMPFILE > $CERTFILE |
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if test -s $CERTFILE ; then |
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echo -----BEGIN CERTIFICATE----- |
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cat $CERTFILE |
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echo -----END CERTIFICATE----- |
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else |
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echo "Couldn't retrieve certificate. openssl reported the following errors:" |
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cat $ERRFILE |
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fi |
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rm -r $TMPDIR
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