Scripts to determine network settings

script/host/net/printOwnIPv4Adress.sh

@@ -0,0 +1,108 @@
+#!/bin/bash
+
+#grep -E '(:|^(127|169\.254|10|172\.(1(6|7|8|9)|2[0-9]|30|31)|192\.168|(22(4|5|6|7|8|9)|23(0|1|2|3|4|5|6|7|8|9))).*)' findet:
+#  loopback:  127.0.0.0/8
+#  linklocal: 169.254.0.0/16
+#  private:   10.0.0.0/8,
+#             172.16.0.0/12,   (172.16… bis 172.31…)
+#             192.168.0.0/16
+# multicast:  224.0.0.0/4      (224… bis 239…)
+
+
+function all() {
+    # Select just lines containing 'inet'.
+    # 1.) Remove every indenting.
+    # 2.) Remove 'inet '.
+    # 3.) Remove everything after a '/' (including the /).
+    ip -4 addr \
+        | grep 'inet' \
+        | sed -e 's/^[[:blank:]]*//' \
+            -e 's/inet //' \
+            -e 's/\/.*//'
+}
+
+function routed() {
+    local _DEVICE
+    _DEVICE="$(ip -4 route show default | xargs -n 1 | grep -A1 -i dev | tail -n 1)"
+    readonly _DEVICE
+
+    ip -4 addr show dev "${_DEVICE:?"Missing DEVICE"}" scope global \
+        | grep 'inet' | xargs -n 1 \
+        | grep -A1 'inet' \
+        | tail -n 1 \
+        | cut -d/ -f1
+}
+
+function public() {
+    hostname -I | xargs -n 1 \
+        | grep -vE '(:|^(127|169\.254|10|172\.(1(6|7|8|9)|2[0-9]|30|31)|192\.168|(22(4|5|6|7|8|9)|23(0|1|2|3|4|5|6|7|8|9))).*)'
+}
+
+# Maybe use "resolvectl status" to get DNS Server and specify 'nslookup'
+function published() {
+    local _BOOT_HOSTNAME
+    _BOOT_HOSTNAME="$(hostname -b)"
+    readonly _BOOT_HOSTNAME
+
+    nslookup -type=A "${_BOOT_HOSTNAME:?"Missing BOOT_HOSTNAME"}" | xargs -n 1 \
+        | grep -A2 -i "${_BOOT_HOSTNAME}" \
+        | grep -A1 -i 'address' \
+        | tail -n1
+}
+
+function verified() {
+    local _PUBLISHED_IP
+    _PUBLISHED_IP="$(published)"
+    readonly _PUBLISHED_IP
+
+    [ -z "${_PUBLISHED_IP}" ] \
+        && return 0
+
+    all | grep "${_PUBLISHED_IP}"
+}
+
+function usage() {
+    echo "Use one of the following options:"
+    echo "  --all       : prints all IPv4 addresses"
+    echo "  --routed    : prints the IPv4 address used to send traffic to the default gateway"
+    echo "  --public    : prints all IPv4 addresses direct accessable from the internet"
+    echo "  --published : prints the IPv4 address provided by DNS using this host's name"
+    echo "  --verified  : prints the IPv4 included in 'all' und respended by 'published'"
+}
+
+
+
+function main(){
+
+    case "${1}" in
+        --all)
+            all
+            return 0
+            ;;
+        --routed)
+            routed
+            return 0
+            ;;
+        --public)
+            public
+            return 0
+            ;;
+        --published)
+            published
+            return 0
+            ;;
+        --verified)
+            verified
+            return 0
+            ;;
+        *)
+            usage
+            return 1
+            ;;
+    esac
+
+    return 1
+
+}
+
+ main "$@" && exit 0 || exit 1