From f8bdc2eedd1c7b028c900b0af99ee5e68190c082 Mon Sep 17 00:00:00 2001
From: Mike Crute <mike@crute.us>
Date: Wed, 16 Aug 2017 16:54:18 +0000
Subject: Add phonehome script

---
 phonehome.sh | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100755 phonehome.sh

diff --git a/phonehome.sh b/phonehome.sh
new file mode 100755
index 0000000..f469d6c
--- /dev/null
+++ b/phonehome.sh
@@ -0,0 +1,52 @@
+#!/bin/bash
+#
+# Alternate Access Tunnel for Remote Hosts
+#
+# Opens an SSH connection to a central aggregation host and forwards the local
+# SSH port over that connection. This allows remote connections to the server
+# from the central aggregation host. In the absence of true OOB recovery
+# systems this mechanism provides some OOB recovery capability provided the
+# entire internet connection is not down.
+#
+
+KEY=/root/.ssh/phonehome.id_rsa
+CRONTAB=/var/spool/cron/crontabs/root
+CRON_ENTRY="*/5 * * * * /root/phonehome.sh"
+
+# Alt host hedges against DNS being down if the default DNS server is on the
+# wrong side of a collapsed ssh tunnel
+#
+# Grab only answers starting with numbers since we're trying to resolve the IP
+# itself not the hostname (in the absence of normal DNS). Grab the first numeric
+# answer in the case of multiple records
+HOST_IP=$(dig +short @8.8.8.8 phonehome.crute.me | awk '/^[0-9]+/ { print $0; exit; }')
+
+function start_autossh {
+    autossh -f \
+        -gNxCT \
+        -l phonehome -p 4321 $1 \
+        -i $KEY \
+        -R $REMOTE_PORT:localhost:22
+}
+
+if [ ! -f /etc/default/phonehome ]; then
+    echo "echo 'REMOTE_PORT=1234' > /etc/default/phonehome"
+    exit 1
+else
+    source /etc/default/phonehome
+fi
+
+if ! grep 'phonehome.sh' $CRONTAB 2>&1 > /dev/null; then
+    echo "Not in crontab, adding"
+    echo "$CRON_ENTRY" >> $CRONTAB
+else
+    if ! grep -F "$CRON_ENTRY" $CRONTAB 2>&1 > /dev/null; then
+        echo "In crontab but not correct, fixing"
+        sed -i '/phonehome.sh/d' $CRONTAB
+        echo "$CRON_ENTRY" >> $CRONTAB
+    fi
+fi
+
+if ! pgrep autossh > /dev/null; then
+    start_autossh $HOST_IP
+fi
-- 
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