diff --git a/src/mvlc_nng_replay.cc b/src/mvlc_nng_replay.cc
index 7e2f941..f17b89b 100644
--- a/src/mvlc_nng_replay.cc
+++ b/src/mvlc_nng_replay.cc
@@ -187,13 +187,49 @@ size_t fixup_listfile_buffer_message(const BufferType &bufferType, nng_msg *msg,
     return bytesMoved;
 }
 
+std::string socket_get_string_opt(nng_socket s, const char *opt)
+{
+    char *dest = nullptr;
+
+    if (nng_socket_get_string(s, opt, &dest))
+        return {};
+
+    std::string result{*dest};
+    nng_strfree(dest);
+    return result;
+}
+
+void log_socket_info(nng_socket s, const char *info)
+{
+    auto sockName = socket_get_string_opt(s, NNG_OPT_SOCKNAME);
+    auto localAddress = socket_get_string_opt(s, NNG_OPT_LOCADDR);
+    auto remoteAddress = socket_get_string_opt(s, NNG_OPT_REMADDR);
+
+    spdlog::info("{}: {}={}", info, NNG_OPT_SOCKNAME, sockName);
+    spdlog::info("{}: {}={}", info, NNG_OPT_LOCADDR, localAddress);
+    spdlog::info("{}: {}={}", info, NNG_OPT_REMADDR, remoteAddress);
+}
+
 void listfile_reader_producer(
-    nng_socket socket,
+    nng_socket outputSocket,
     mvlc::listfile::ReadHandle &input,
     const BufferType &bufferType)
 {
     prctl(PR_SET_NAME,"listfile_reader_producer",0,0,0);
 
+    #if 0
+    log_socket_info(outputSocket, "listfile_reader_producer - outputSocket");
+
+    if (auto res = nng_close(outputSocket))
+    {
+        spdlog::error("nng_close: {}", nng_strerror(res));
+        log_socket_info(outputSocket, "listfile_reader_producer - outputSocket");
+        return;
+    }
+
+    return;
+    #endif
+
     try
     {
         u32 bufferNumber = 0u;
@@ -238,7 +274,7 @@ void listfile_reader_producer(
 
             const auto msgSize = nng_msg_len(msg);
 
-            if (auto res = send_message_retry(socket, msg, 0, "listfile_reader_producer"))
+            if (auto res = send_message_retry(outputSocket, msg, 0, "listfile_reader_producer"))
             {
                 nng_msg_free(msg);
                 msg = nullptr;
@@ -493,27 +529,14 @@ private:
 void listfile_parser_nng(
     nng_socket inputSocket,
     nng_socket outputSocket,
-    const mvlc::listfile::Preamble &preamble)
+    const mvlc::CrateConfig &crateConfig)
 {
     prctl(PR_SET_NAME,"listfile_parser_nng",0,0,0);
 
     size_t totalInputBytes = 0u;
     u32 lastInputMessageNumber = 0u;
     size_t inputBuffersLost = 0;
-    const auto listfileFormat = (preamble.magic == mvlc::listfile::get_filemagic_eth()
-                                     ? ConnectionType::ETH
-                                     : ConnectionType::USB);
-
-    auto configSection = preamble.findCrateConfig();
-
-    if (!configSection)
-    {
-        spdlog::error("listfile_parser_nng - no CrateConfig found in listfile preamble");
-        return;
-    }
-
-    auto configYaml = configSection->contentsToString();
-    auto crateConfig = mvlc::crate_config_from_yaml(configYaml);
+    const auto listfileFormat = crateConfig.connectionType;
 
     std::string stacksYaml;
     for (const auto &stack: crateConfig.stacks)
@@ -786,7 +809,42 @@ int main(int argc, char *argv[])
     spdlog::set_level(spdlog::level::info);
 
     if (argc < 2)
+    {
+        std::cerr << fmt::format("Usage: mvlc_nng_replay <zipfile>\n");
         return 1;
+    }
+
+    const auto inputFilename = argv[1];
+
+    listfile::ZipReader zipReader;
+    try
+    {
+        zipReader.openArchive(inputFilename);
+    }
+    catch (const std::exception &e)
+    {
+        std::cout << fmt::format("Error: could not open '{}' for reading: {}\n", inputFilename, e.what());
+        return 1;
+    }
+
+    listfile::ReadHandle *readHandle = nullptr;
+
+    try
+    {
+        readHandle = zipReader.openEntry(zipReader.firstListfileEntryName());
+    }
+    catch(const std::exception& e)
+    {
+        if (zipReader.firstListfileEntryName().empty())
+            std::cout << fmt::format("Error: no MVLC listfile found in '{}'\n", inputFilename);
+        else
+            std::cout << fmt::format("Error: could not open listfile '{}' in '{}' for reading: {}\n",
+                zipReader.firstListfileEntryName(), inputFilename, e.what());
+
+        return 1;
+    }
+
+    assert(readHandle);
 
     try
     {
@@ -795,11 +853,15 @@ int main(int argc, char *argv[])
         if (int res = nng_listen(readerOutputSocket, "inproc://1", nullptr, 0))
             mesy_nng_fatal("nng_listen inproc", res);
 
+        log_socket_info(readerOutputSocket, "readerOutputSocket");
+
         auto parserInputSocket = make_pair_socket();
 
         if (int res = nng_dial(parserInputSocket, "inproc://1", nullptr, 0))
             mesy_nng_fatal("nng_dial inproc", res);
 
+        log_socket_info(parserInputSocket, "parserInputSocket");
+
         auto parserOutputSocket = make_pair_socket();
 
         if (int res = nng_listen(parserOutputSocket, "inproc://2", nullptr, 0))
@@ -810,15 +872,25 @@ int main(int argc, char *argv[])
         if (int res = nng_dial(analysisInputSocket, "inproc://2", nullptr, 0))
             mesy_nng_fatal("nng_dial inproc", res);
 
-        listfile::ZipReader zipReader;
-        zipReader.openArchive(argv[1]);
         spdlog::info("replaying from {}", zipReader.firstListfileEntryName());
-        auto readHandle = zipReader.openEntry(zipReader.firstListfileEntryName());
         auto preamble = mvlc::listfile::read_preamble(*readHandle);
         const auto bufferType = (preamble.magic == mvlc::listfile::get_filemagic_eth()
                                      ? BufferType::MVLC_ETH
                                      : BufferType::MVLC_USB);
-        // Read past the magic bytes at the start of each listfile.
+        auto crateConfigSection = preamble.findCrateConfig();
+
+        if (!crateConfigSection)
+        {
+            spdlog::error("listfile_parser_nng - no CrateConfig found in listfile preamble");
+            // FIXME: close sockets
+            return 1;
+        }
+
+        auto configYaml = crateConfigSection->contentsToString();
+        auto crateConfig = mvlc::crate_config_from_yaml(configYaml);
+
+        // Seek to start, then read past the magic bytes at the beginning of the
+        // listfile.
         (void) listfile::read_magic(*readHandle);
 
         std::vector<std::thread> threads;
@@ -827,7 +899,7 @@ int main(int argc, char *argv[])
             readerOutputSocket, std::ref(*readHandle), std::cref(bufferType)));
 
         threads.emplace_back(std::thread(listfile_parser_nng,
-            parserInputSocket, parserOutputSocket, std::cref(preamble)));
+            parserInputSocket, parserOutputSocket, std::cref(crateConfig)));
 
         threads.emplace_back(std::thread(analysis_nng,
             analysisInputSocket));