T6641: Add vyos-network-event-logger Service

The service parses and logs network events for improved monitoring and diagnostics.
Supported event types include:

- `RTM_NEWROUTE`, `RTM_DELROUTE`
- `RTM_NEWLINK`, `RTM_DELLINK`
- `RTM_NEWADDR`, `RTM_DELADDR`
- `RTM_NEWNEIGH`, `RTM_DELNEIGH`, `RTM_GETNEIGH`
- `RTM_NEWRULE`, `RTM_DELRULE`

Added operational mode commands for filtered log retrieval:
- `show log network-event <event-type> <interface>`: Retrieve logs filtered by event type and interface.
- `show interfaces <type> <name> event-log <event-type>`: Display interface-specific logs filtered by event type.

1 files changed, 63 insertions, 0 deletions

diff --git a/python/vyos/include/uapi/linux/rtnetlink.py b/python/vyos/include/uapi/linux/rtnetlink.py
new file mode 100644
index 000000000..e31272460
--- /dev/null
+++ b/python/vyos/include/uapi/linux/rtnetlink.py
@@ -0,0 +1,63 @@
+# Copyright (C) 2025 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+RTM_F_NOTIFY = 0x100
+RTM_F_CLONED = 0x200
+RTM_F_EQUALIZE = 0x400
+RTM_F_PREFIX = 0x800
+RTM_F_LOOKUP_TABLE = 0x1000
+RTM_F_FIB_MATCH = 0x2000
+RTM_F_OFFLOAD = 0x4000
+RTM_F_TRAP = 0x8000
+RTM_F_OFFLOAD_FAILED = 0x20000000
+
+RTNH_F_DEAD = 1
+RTNH_F_PERVASIVE = 2
+RTNH_F_ONLINK = 4
+RTNH_F_OFFLOAD = 8
+RTNH_F_LINKDOWN = 16
+RTNH_F_UNRESOLVED = 32
+RTNH_F_TRAP = 64
+
+RT_TABLE_COMPAT = 252
+RT_TABLE_DEFAULT = 253
+RT_TABLE_MAIN = 254
+RT_TABLE_LOCAL = 255
+
+RTAX_FEATURE_ECN = (1 << 0)
+RTAX_FEATURE_SACK = (1 << 1)
+RTAX_FEATURE_TIMESTAMP = (1 << 2)
+RTAX_FEATURE_ALLFRAG = (1 << 3)
+RTAX_FEATURE_TCP_USEC_TS = (1 << 4)
+
+RT_FlAGS = {
+    'dead': RTNH_F_DEAD,
+    'onlink': RTNH_F_ONLINK,
+    'pervasive':  RTNH_F_PERVASIVE,
+    'offload': RTNH_F_OFFLOAD,
+    'trap': RTNH_F_TRAP,
+    'notify': RTM_F_NOTIFY,
+    'linkdown': RTNH_F_LINKDOWN,
+    'unresolved': RTNH_F_UNRESOLVED,
+    'rt_offload': RTM_F_OFFLOAD,
+    'rt_trap': RTM_F_TRAP,
+    'rt_offload_failed': RTM_F_OFFLOAD_FAILED,
+}
+
+RT_TABLE_TO_NAME = {
+    RT_TABLE_COMPAT: 'compat',
+    RT_TABLE_DEFAULT: 'default',
+    RT_TABLE_MAIN: 'main',
+    RT_TABLE_LOCAL: 'local',
+}