diff --git a/eng/pipelines/templates/steps/ci.test.yml b/eng/pipelines/templates/steps/ci.test.yml
index b415e1f567..d6d9a67f7e 100644
--- a/eng/pipelines/templates/steps/ci.test.yml
+++ b/eng/pipelines/templates/steps/ci.test.yml
@@ -103,7 +103,9 @@ steps:
 # Validate all the files are saved as ASCII only without a UTF-8 BOM.
 - bash: |
     # Run grep recursive excluding git folder and known expected files and save a file with results.
-    grep -I -P -n "[^\x00-\x7F]" -r --exclude-dir ".git" --exclude-dir "vcpkg_installed" --exclude-dir "_deps" --exclude-dir "docs" --exclude-dir "eng" --exclude-dir "tools" --exclude "*CodeCoverage.cmake*" --exclude "grepResults" . > grepResults
+    # ".github" holds repo tooling/skill markdown (not shippable SDK source) which intentionally
+    # contains non-ASCII characters (e.g. em dashes); exclude it like eng/docs/tools.
+    grep -I -P -n "[^\x00-\x7F]" -r --exclude-dir ".git" --exclude-dir ".github" --exclude-dir "vcpkg_installed" --exclude-dir "_deps" --exclude-dir "docs" --exclude-dir "eng" --exclude-dir "tools" --exclude "*CodeCoverage.cmake*" --exclude "grepResults" . > grepResults
 
     # Display results to console.
     cat grepResults
diff --git a/eng/vcpkg-overlay-ports/cmocka/portfile.cmake b/eng/vcpkg-overlay-ports/cmocka/portfile.cmake
new file mode 100644
index 0000000000..2f35513d0b
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/cmocka/portfile.cmake
@@ -0,0 +1,48 @@
+# Overlay port: cmocka
+#
+# Why this overlay exists:
+#   The upstream vcpkg `cmocka` port downloads the source from gitlab.com via
+#   `vcpkg_from_gitlab(...)`. 1ES build agents permanently block gitlab.com, so the
+#   download fails hard with `curl error code 7 (Couldn't connect to server)` and the
+#   Linux unit-test job cannot build. See Azure/azure-sdk-for-c#3464.
+#
+# What this overlay changes:
+#   It sources the *same* cmocka release (2.0.2) from the project's official file
+#   server (https://cmocka.org/files) instead of gitlab.com. The SHA512 below was
+#   computed from https://cmocka.org/files/2.0/cmocka-2.0.2.tar.xz. Every other build
+#   step is identical to the upstream port.
+#
+# Scope / lifetime:
+#   This is a SHORT-TERM unblock. cmocka.org is itself slated to be denied on build
+#   agents, so the durable fix is vcpkg + Terrapin (an approved download mirror /
+#   asset cache) configured at the pipeline level. Remove this overlay once Terrapin
+#   (or an equivalent approved asset source) is in place. See #3464 for details.
+
+vcpkg_download_distfile(ARCHIVE
+    URLS "https://cmocka.org/files/2.0/cmocka-${VERSION}.tar.xz"
+    FILENAME "cmocka-${VERSION}.tar.xz"
+    SHA512 d02d65f0881f18f30b9e46c325acfa349261339daa2c1bf3a4e6360976f13b31588e997415197220f6def156f77d9864994d4e3cfd09c8f16a8594d0a4789a16
+)
+
+vcpkg_extract_source_archive(SOURCE_PATH
+    ARCHIVE "${ARCHIVE}"
+)
+
+vcpkg_cmake_configure(
+    SOURCE_PATH "${SOURCE_PATH}"
+    OPTIONS
+        -DUNIT_TESTING=OFF
+        -DWITH_EXAMPLES=OFF
+        -DPICKY_DEVELOPER=OFF
+)
+
+vcpkg_cmake_install()
+
+vcpkg_copy_pdbs()
+
+vcpkg_cmake_config_fixup(CONFIG_PATH lib/cmake/${PORT})
+vcpkg_fixup_pkgconfig()
+
+file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/include")
+
+vcpkg_install_copyright(FILE_LIST "${SOURCE_PATH}/LICENSE")
diff --git a/eng/vcpkg-overlay-ports/cmocka/vcpkg.json b/eng/vcpkg-overlay-ports/cmocka/vcpkg.json
new file mode 100644
index 0000000000..74bfcded9b
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/cmocka/vcpkg.json
@@ -0,0 +1,17 @@
+{
+  "name": "cmocka",
+  "version": "2.0.2",
+  "description": "An elegant unit testing framework for C with support for mock objects",
+  "homepage": "https://cmocka.org",
+  "license": "Apache-2.0",
+  "dependencies": [
+    {
+      "name": "vcpkg-cmake",
+      "host": true
+    },
+    {
+      "name": "vcpkg-cmake-config",
+      "host": true
+    }
+  ]
+}
diff --git a/eng/vcpkg-overlay-ports/libuuid/CMakeLists.txt b/eng/vcpkg-overlay-ports/libuuid/CMakeLists.txt
new file mode 100644
index 0000000000..50827ae79a
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/libuuid/CMakeLists.txt
@@ -0,0 +1,64 @@
+cmake_minimum_required(VERSION 3.21)
+project(libuuid C)
+
+configure_file(config.linux.h config.h COPYONLY)
+
+include_directories(${CMAKE_CURRENT_BINARY_DIR})
+
+add_library(uuid STATIC
+    clear.c
+    compare.c
+    copy.c
+    gen_uuid.c
+    isnull.c
+    pack.c
+    parse.c
+    randutils.c
+    unpack.c
+    unparse.c
+    uuid_time.c
+)
+target_compile_options(uuid PRIVATE -include "${CMAKE_CURRENT_BINARY_DIR}/config.h")
+target_include_directories(uuid PUBLIC "$<INSTALL_INTERFACE:include>")
+
+add_executable(test_uuid test_uuid.c)
+target_link_libraries(test_uuid uuid)
+
+if(CMAKE_BUILD_TYPE STREQUAL "Release")
+    install(FILES uuid.h DESTINATION include/uuid)
+endif()
+
+install(
+    TARGETS uuid
+    EXPORT uuid_targets
+    RUNTIME DESTINATION bin
+    LIBRARY DESTINATION lib
+    ARCHIVE DESTINATION lib
+)
+
+include(CMakePackageConfigHelpers)
+set(PACKAGE_CONFIG_FILE "${CMAKE_CURRENT_BINARY_DIR}/unofficial-libuuid-config.cmake")
+set(INSTALL_CONFIG_DIR  "${CMAKE_INSTALL_LIBDIR}/cmake/unofficial-libuuid")
+
+configure_package_config_file(unofficial-libuuid-config.cmake.in
+    "${PACKAGE_CONFIG_FILE}"
+    INSTALL_DESTINATION "${INSTALL_CONFIG_DIR}"
+)
+
+export(EXPORT uuid_targets
+    NAMESPACE unofficial::UUID::
+    FILE "${CMAKE_CURRENT_BINARY_DIR}/unofficial-libuuid-targets.cmake"
+)
+
+install(EXPORT uuid_targets
+    NAMESPACE unofficial::UUID::
+    FILE unofficial-libuuid-targets.cmake
+    DESTINATION "${INSTALL_CONFIG_DIR}"
+)
+
+install(
+    FILES
+        "${PACKAGE_CONFIG_FILE}"
+    DESTINATION
+        "${INSTALL_CONFIG_DIR}"
+)
diff --git a/eng/vcpkg-overlay-ports/libuuid/config.linux.h b/eng/vcpkg-overlay-ports/libuuid/config.linux.h
new file mode 100644
index 0000000000..38b53cac1c
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/libuuid/config.linux.h
@@ -0,0 +1,13 @@
+#define HAVE_DECL__SC_HOST_NAME_MAX 1
+#define HAVE_INTTYPES_H 1
+#define HAVE_NETINET_IN_H 1
+#define HAVE_SRANDOM 1
+#define HAVE_STDINT_H 1
+#define HAVE_STDLIB_H 1
+#define HAVE_SYS_FILE_H 1
+#define HAVE_SYS_IOCTL_H 1
+#define HAVE_SYS_SOCKET_H 1
+#define HAVE_SYS_TIME_H 1
+#define HAVE_UNISTD_H 1
+#define HAVE_USLEEP 1
+#define PACKAGE_STRING "libuuid 1.0.3"
diff --git a/eng/vcpkg-overlay-ports/libuuid/portfile.cmake b/eng/vcpkg-overlay-ports/libuuid/portfile.cmake
new file mode 100644
index 0000000000..d77cba7f5d
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/libuuid/portfile.cmake
@@ -0,0 +1,65 @@
+# Overlay port: libuuid
+#
+# Why this overlay exists:
+#   The upstream vcpkg `libuuid` port downloads the source from SourceForge via
+#   `vcpkg_from_sourceforge(...)`. 1ES build agents permanently block sourceforge.net
+#   (every mirror returns `curl error code 7 (Couldn't connect to server)`), so any
+#   Linux job that builds libuuid fails. libuuid is a transitive dependency of both
+#   `paho-mqtt` and `curl`, which the root vcpkg.json manifest installs on every
+#   Linux job. See Azure/azure-sdk-for-c#3464 (same class as the cmocka/gitlab block).
+#
+# What this overlay changes:
+#   It sources the *same* libuuid release (1.0.3) from the MacPorts distfiles mirror
+#   instead of SourceForge. The SHA512 below is unchanged from the upstream port and
+#   was re-verified against
+#   https://distfiles.macports.org/libuuid/libuuid-1.0.3.tar.gz (identical bytes).
+#   Every other build step is identical to the upstream port.
+#
+# Scope / lifetime:
+#   This is a SHORT-TERM unblock. The durable fix is vcpkg + Terrapin (an approved
+#   download mirror / asset cache) configured at the pipeline level, which removes the
+#   need for any blocked-origin download. Remove this overlay once that is in place.
+
+set(LIBUUID_VERSION 1.0.3)
+
+vcpkg_download_distfile(ARCHIVE
+    URLS "https://distfiles.macports.org/libuuid/libuuid-${LIBUUID_VERSION}.tar.gz"
+    FILENAME "libuuid-${LIBUUID_VERSION}.tar.gz"
+    SHA512 77488caccc66503f6f2ded7bdfc4d3bc2c20b24a8dc95b2051633c695e99ec27876ffbafe38269b939826e1fdb06eea328f07b796c9e0aaca12331a787175507
+)
+
+vcpkg_extract_source_archive(SOURCE_PATH
+    ARCHIVE "${ARCHIVE}"
+)
+
+file(COPY
+    "${CMAKE_CURRENT_LIST_DIR}/CMakeLists.txt"
+    "${CMAKE_CURRENT_LIST_DIR}/config.linux.h"
+    "${CMAKE_CURRENT_LIST_DIR}/unofficial-libuuid-config.cmake.in"
+    DESTINATION "${SOURCE_PATH}"
+)
+
+vcpkg_cmake_configure(
+    SOURCE_PATH "${SOURCE_PATH}"
+)
+
+vcpkg_cmake_install()
+
+set(prefix "${CURRENT_INSTALLED_DIR}")
+set(exec_prefix \$\{prefix\})
+set(libdir \$\{exec_prefix\}/lib)
+set(includedir \$\{prefix\}/include)
+configure_file("${SOURCE_PATH}/uuid.pc.in" "${SOURCE_PATH}/uuid.pc" @ONLY)
+if(NOT DEFINED VCPKG_BUILD_TYPE OR VCPKG_BUILD_TYPE STREQUAL "release")
+    file(INSTALL "${SOURCE_PATH}/uuid.pc" DESTINATION "${CURRENT_PACKAGES_DIR}/lib/pkgconfig")
+endif()
+if(NOT DEFINED VCPKG_BUILD_TYPE OR VCPKG_BUILD_TYPE STREQUAL "debug")
+    file(INSTALL "${SOURCE_PATH}/uuid.pc" DESTINATION "${CURRENT_PACKAGES_DIR}/debug/lib/pkgconfig")
+endif()
+
+vcpkg_cmake_config_fixup(CONFIG_PATH lib/cmake/unofficial-libuuid PACKAGE_NAME unofficial-libuuid)
+vcpkg_fixup_pkgconfig()
+
+vcpkg_install_copyright(FILE_LIST "${SOURCE_PATH}/COPYING")
+
+vcpkg_copy_pdbs()
diff --git a/eng/vcpkg-overlay-ports/libuuid/unofficial-libuuid-config.cmake.in b/eng/vcpkg-overlay-ports/libuuid/unofficial-libuuid-config.cmake.in
new file mode 100644
index 0000000000..19123d9470
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/libuuid/unofficial-libuuid-config.cmake.in
@@ -0,0 +1,3 @@
+@PACKAGE_INIT@
+
+include("${CMAKE_CURRENT_LIST_DIR}/unofficial-libuuid-targets.cmake")
diff --git a/eng/vcpkg-overlay-ports/libuuid/vcpkg.json b/eng/vcpkg-overlay-ports/libuuid/vcpkg.json
new file mode 100644
index 0000000000..4cefc114b9
--- /dev/null
+++ b/eng/vcpkg-overlay-ports/libuuid/vcpkg.json
@@ -0,0 +1,19 @@
+{
+  "name": "libuuid",
+  "version": "1.0.3",
+  "port-version": 16,
+  "description": "Universally unique id library",
+  "homepage": "https://sourceforge.net/projects/libuuid/",
+  "license": "BSD-3-Clause",
+  "supports": "!osx & !windows",
+  "dependencies": [
+    {
+      "name": "vcpkg-cmake",
+      "host": true
+    },
+    {
+      "name": "vcpkg-cmake-config",
+      "host": true
+    }
+  ]
+}
diff --git a/vcpkg-configuration.json b/vcpkg-configuration.json
new file mode 100644
index 0000000000..1924602513
--- /dev/null
+++ b/vcpkg-configuration.json
@@ -0,0 +1,6 @@
+{
+  "$schema": "https://raw.githubusercontent.com/microsoft/vcpkg-tool/main/docs/vcpkg-configuration.schema.json",
+  "overlay-ports": [
+    "./eng/vcpkg-overlay-ports"
+  ]
+}