Test Connectivity

1#!/bin/bash
2# Test network connectivity to an RDS Oracle endpoint
3# Usage: bash test_connectivity.sh <rds-endpoint> [port]
4#
5# Checks: DNS resolution, TCP connectivity, port reachability
6
7set -euo pipefail
8
9ENDPOINT="${1:?Usage: $0 <rds-endpoint> [port]}"
10PORT="${2:-1521}"
11
12echo "=== RDS Oracle Connectivity Test ==="
13echo "Endpoint: ${ENDPOINT}"
14echo "Port:     ${PORT}"
15echo "Time:     $(date)"
16echo ""
17
18# 1. DNS Resolution
19echo "--- DNS Resolution ---"
20if nslookup "${ENDPOINT}" > /dev/null 2>&1; then
21    IP=$(nslookup "${ENDPOINT}" 2>/dev/null | grep -A1 "Name:" | grep "Address:" | head -1 | awk '{print $2}')
22    if [ -z "$IP" ]; then
23        IP=$(dig +short "${ENDPOINT}" 2>/dev/null | head -1)
24    fi
25    echo "PASS: ${ENDPOINT} resolves to ${IP:-unknown}"
26else
27    echo "FAIL: Cannot resolve ${ENDPOINT}"
28    echo "  Check: VPC DNS resolution enabled, DNS hostnames enabled"
29    exit 1
30fi
31echo ""
32
33# 2. TCP Connectivity
34echo "--- TCP Connectivity (port ${PORT}) ---"
35if nc -zw5 "${ENDPOINT}" "${PORT}" 2>/dev/null; then
36    echo "PASS: TCP connection to ${ENDPOINT}:${PORT} succeeded"
37elif bash -c "echo > /dev/tcp/${ENDPOINT}/${PORT}" 2>/dev/null; then
38    echo "PASS: TCP connection to ${ENDPOINT}:${PORT} succeeded (via /dev/tcp)"
39else
40    echo "FAIL: Cannot connect to ${ENDPOINT}:${PORT}"
41    echo "  Check:"
42    echo "  - Security group inbound rules allow TCP ${PORT} from your source"
43    echo "  - RDS instance is in 'available' state"
44    echo "  - Network ACLs allow traffic on port ${PORT}"
45    echo "  - If cross-VPC: VPC peering/TGW routes are configured"
46    exit 1
47fi
48echo ""
49
50# 3. Check if this looks like an RDS endpoint
51echo "--- Endpoint Validation ---"
52if echo "${ENDPOINT}" | grep -q "rds.amazonaws.com"; then
53    echo "PASS: Endpoint matches RDS format (*.rds.amazonaws.com)"
54    REGION=$(echo "${ENDPOINT}" | sed -n 's/.*\.\([a-z0-9-]*\)\.rds\.amazonaws\.com/\1/p')
55    echo "  Region: ${REGION}"
56else
57    echo "WARN: Endpoint does not match standard RDS format"
58    echo "  Expected: <instance>.xxxxxxxxxxxx.<region>.rds.amazonaws.com"
59    echo "  This may be a Route 53 CNAME or CMAN endpoint — that's OK"
60fi
61echo ""
62
63echo "=== All connectivity checks passed ==="