diff --git a/src/crimson/CMakeLists.txt b/src/crimson/CMakeLists.txt
index cff5f86c01b..410f59aa97d 100644
--- a/src/crimson/CMakeLists.txt
+++ b/src/crimson/CMakeLists.txt
@@ -80,6 +80,7 @@ add_library(crimson-common STATIC
   ${PROJECT_SOURCE_DIR}/src/msg/msg_types.cc
   ${PROJECT_SOURCE_DIR}/src/msg/Message.cc
   ${PROJECT_SOURCE_DIR}/src/mon/MonCap.cc
+  ${PROJECT_SOURCE_DIR}/src/mon/MonMap.cc
   ${PROJECT_SOURCE_DIR}/src/osd/osd_types.cc
   ${PROJECT_SOURCE_DIR}/src/osd/ECMsgTypes.cc
   ${PROJECT_SOURCE_DIR}/src/osd/HitSet.cc
@@ -110,7 +111,6 @@ set(crimson_auth_srcs
   auth/KeyRing.cc)
 set(crimson_mon_srcs
   mon/MonClient.cc
-  ${PROJECT_SOURCE_DIR}/src/mon/MonMap.cc
   ${PROJECT_SOURCE_DIR}/src/mon/MonSub.cc)
 set(crimson_net_srcs
   net/Dispatcher.cc
@@ -134,3 +134,4 @@ target_link_libraries(crimson
     crimson-common
     crimson::cflags)
 add_subdirectory(os)
+add_subdirectory(osd)
diff --git a/src/crimson/osd/CMakeLists.txt b/src/crimson/osd/CMakeLists.txt
new file mode 100644
index 00000000000..2c109366460
--- /dev/null
+++ b/src/crimson/osd/CMakeLists.txt
@@ -0,0 +1,5 @@
+add_executable(crimson-osd
+  main.cc
+  osd.cc)
+target_link_libraries(crimson-osd
+  crimson-common crimson-os crimson)
diff --git a/src/crimson/osd/main.cc b/src/crimson/osd/main.cc
new file mode 100644
index 00000000000..1d7e9297a3f
--- /dev/null
+++ b/src/crimson/osd/main.cc
@@ -0,0 +1,81 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:nil -*-
+// vim: ts=8 sw=2 smarttab
+
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <iostream>
+
+#include <seastar/core/app-template.hh>
+#include <seastar/core/thread.hh>
+
+#include "common/ceph_argparse.h"
+#include "crimson/common/config_proxy.h"
+
+#include "osd.h"
+
+using config_t = ceph::common::ConfigProxy;
+
+void usage(const char* prog) {
+  std::cout << "usage: " << prog << " -i <ID>" << std::endl;
+  generic_server_usage();
+}
+
+int main(int argc, char* argv[])
+{
+  std::vector<const char*> args{argv + 1, argv + argc};
+  if (ceph_argparse_need_usage(args)) {
+    usage(argv[0]);
+    return EXIT_SUCCESS;
+  }
+  std::string cluster;
+  std::string conf_file_list;
+  // ceph_argparse_early_args() could _exit(), while local_conf() won't ready
+  // until it's started. so do the boilerplate-settings parsing here.
+  auto init_params = ceph_argparse_early_args(args,
+                                              CEPH_ENTITY_TYPE_OSD,
+                                              &cluster,
+                                              &conf_file_list);
+  seastar::app_template app;
+  seastar::sharded<OSD> osd;
+
+  using ceph::common::sharded_conf;
+  using ceph::common::sharded_perf_coll;
+  using ceph::common::local_conf;
+
+  args.insert(begin(args), argv[0]);
+  try {
+    return app.run_deprecated(args.size(), const_cast<char**>(args.data()), [&] {
+      seastar::engine().at_exit([] {
+        return sharded_conf().stop();
+      });
+      seastar::engine().at_exit([] {
+        return sharded_perf_coll().stop();
+      });
+      seastar::engine().at_exit([&] {
+       return osd.stop();
+      });
+      return sharded_conf().start(init_params.name, cluster).then([] {
+        return sharded_perf_coll().start();
+      }).then([&conf_file_list] {
+        return local_conf().parse_config_files(conf_file_list);
+      }).then([&] {
+        return osd.start_single(std::stoi(local_conf()->name.get_id()),
+                                static_cast<uint32_t>(getpid()));
+      }).then([&] {
+        return osd.invoke_on(0, &OSD::start);
+      });
+    });
+  } catch (...) {
+    seastar::fprint(std::cerr, "FATAL: Exception during startup, aborting: %s\n", std::current_exception());
+    return EXIT_FAILURE;
+  }
+}
+
+/*
+ * Local Variables:
+ * compile-command: "make -j4 \
+ * -C ../../../build \
+ * crimson-osd"
+ * End:
+ */
diff --git a/src/crimson/osd/osd.cc b/src/crimson/osd/osd.cc
new file mode 100644
index 00000000000..5692edc7a14
--- /dev/null
+++ b/src/crimson/osd/osd.cc
@@ -0,0 +1,42 @@
+#include "osd.h"
+
+#include "crimson/net/SocketMessenger.h"
+
+namespace {
+  seastar::logger& logger() {
+    return ceph::get_logger(ceph_subsys_osd);
+  }
+}
+
+using ceph::common::local_conf;
+
+OSD::OSD(int id, uint32_t nonce)
+  : whoami{id},
+    cluster_msgr{new ceph::net::SocketMessenger{entity_name_t::OSD(whoami),
+                                                "cluster", nonce}},
+    client_msgr{new ceph::net::SocketMessenger{entity_name_t::OSD(whoami),
+                                               "client", nonce}},
+    monc{*client_msgr}
+{
+  for (auto msgr : {cluster_msgr.get(), client_msgr.get()}) {
+    if (local_conf()->ms_crc_data) {
+      msgr->set_crc_data();
+    }
+    if (local_conf()->ms_crc_header) {
+      msgr->set_crc_header();
+    }
+  }
+}
+
+OSD::~OSD() = default;
+
+seastar::future<> OSD::start()
+{
+  logger().info("start");
+  return seastar::now();
+}
+
+seastar::future<> OSD::stop()
+{
+  return gate.close();
+}
diff --git a/src/crimson/osd/osd.h b/src/crimson/osd/osd.h
new file mode 100644
index 00000000000..a648f136461
--- /dev/null
+++ b/src/crimson/osd/osd.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <seastar/core/future.hh>
+#include <seastar/core/gate.hh>
+
+#include "crimson/net/Dispatcher.h"
+
+namespace ceph::net {
+  class Messenger;
+}
+
+class OSD : public ceph::net::Dispatcher {
+  seastar::gate gate;
+  const int whoami;
+  // talk with osd
+  std::unique_ptr<ceph::net::Messenger> cluster_msgr;
+  // talk with mon/mgr
+  std::unique_ptr<ceph::net::Messenger> client_msgr;
+
+public:
+  OSD(int id, uint32_t nonce);
+  ~OSD();
+
+  seastar::future<> start();
+  seastar::future<> stop();
+};