diff --git a/client/status.go b/client/status.go
index 5182772..7847c84 100644
--- a/client/status.go
+++ b/client/status.go
@@ -62,7 +62,7 @@ func (t *tui) addIndent(indent int) {
 	t.moveLine(0, 0)
 }
 
-func RunStatus(config config.Config, args []string) error {
+func RunStatus(config *config.Config, args []string) error {
 	httpc, err := controlHttpClient(config.Global.Control.SockPath)
 	if err != nil {
 		return err
diff --git a/client/wakeup.go b/client/wakeup.go
index 97fb180..d6a224f 100644
--- a/client/wakeup.go
+++ b/client/wakeup.go
@@ -6,7 +6,7 @@ import (
 	"github.com/zrepl/zrepl/daemon"
 )
 
-func RunWakeup(config config.Config, args []string) error {
+func RunWakeup(config *config.Config, args []string) error {
 	if len(args) != 1 {
 		return errors.Errorf("Expected 1 argument: job")
 	}
diff --git a/config/config.go b/config/config.go
index 93a7a29..d6a334f 100644
--- a/config/config.go
+++ b/config/config.go
@@ -9,11 +9,12 @@ import (
 	"regexp"
 	"strconv"
 	"time"
+	"reflect"
 )
 
 type Config struct {
 	Jobs   []JobEnum `yaml:"jobs"`
-	Global Global    `yaml:"global"`
+	Global *Global    `yaml:"global,optional,fromdefaults"`
 }
 
 type JobEnum struct {
@@ -102,11 +103,51 @@ type PruningLocal struct {
 	Keep []PruningEnum `yaml:"keep"`
 }
 
+type LoggingOutletEnumList []LoggingOutletEnum
+
+func (l *LoggingOutletEnumList) SetDefault() {
+	def := `
+type: "stdout"
+time: true
+level: "warn"
+format: "human"
+`
+	s := StdoutLoggingOutlet{}
+	err := yaml.UnmarshalStrict([]byte(def), &s)
+	if err != nil {
+		panic(err)
+	}
+	*l = []LoggingOutletEnum{LoggingOutletEnum{Ret: s}}
+}
+
+var _ yaml.Defaulter = &LoggingOutletEnumList{}
+
 type Global struct {
-	Logging    []LoggingOutletEnum `yaml:"logging"`
+	Logging    *LoggingOutletEnumList `yaml:"logging,optional,fromdefaults"`
 	Monitoring []MonitoringEnum    `yaml:"monitoring,optional"`
-	Control    GlobalControl       `yaml:"control"`
-	Serve      GlobalServe         `yaml:"serve"`
+	Control    *GlobalControl       `yaml:"control,optional,fromdefaults"`
+	Serve      *GlobalServe         `yaml:"serve,optional,fromdefaults"`
+	RPC 		*RPCConfig          `yaml:"rpc,optional,fromdefaults"`
+}
+
+func Default(i interface{}) {
+	v := reflect.ValueOf(i)
+	if v.Kind() != reflect.Ptr {
+		panic(v)
+	}
+	y := `{}`
+	err := yaml.Unmarshal([]byte(y), v.Interface())
+	if err != nil {
+		panic(err)
+	}
+}
+
+type RPCConfig struct {
+	Timeout time.Duration `yaml:"timeout,optional,positive,default=10s"`
+	TxChunkSize uint `yaml:"tx_chunk_size,optional,default=32768"`
+	RxStructuredMaxLen uint `yaml:"rx_structured_max,optional,default=16777216"`
+	RxStreamChunkMaxLen uint `yaml:"rx_stream_chunk_max,optional,default=16777216"`
+	RxHeaderMaxLen uint `yaml:"rx_header_max,optional,default=40960"`
 }
 
 type ConnectEnum struct {
@@ -115,12 +156,14 @@ type ConnectEnum struct {
 
 type TCPConnect struct {
 	Type        string        `yaml:"type"`
+	RPC 		*RPCConfig	   `yaml:"rpc,optional"`
 	Address     string        `yaml:"address"`
 	DialTimeout time.Duration `yaml:"dial_timeout,positive,default=10s"`
 }
 
 type TLSConnect struct {
 	Type        string        `yaml:"type"`
+	RPC 		*RPCConfig	   `yaml:"rpc,optional"`
 	Address     string        `yaml:"address"`
 	Ca          string        `yaml:"ca"`
 	Cert        string        `yaml:"cert"`
@@ -131,6 +174,7 @@ type TLSConnect struct {
 
 type SSHStdinserverConnect struct {
 	Type                 string        `yaml:"type"`
+	RPC 		*RPCConfig	   `yaml:"rpc,optional"`
 	Host                 string        `yaml:"host"`
 	User                 string        `yaml:"user"`
 	Port                 uint16        `yaml:"port"`
@@ -233,7 +277,7 @@ type GlobalControl struct {
 }
 
 type GlobalServe struct {
-	StdinServer GlobalStdinServer `yaml:"stdinserver"`
+	StdinServer *GlobalStdinServer `yaml:"stdinserver,optional,fromdefaults"`
 }
 
 type GlobalStdinServer struct {
@@ -241,10 +285,11 @@ type GlobalStdinServer struct {
 }
 
 type JobDebugSettings struct {
-	Conn struct {
+	Conn *struct {
 		ReadDump  string `yaml:"read_dump"`
 		WriteDump string `yaml:"write_dump"`
-	} `yaml:"conn"`
+	} `yaml:"conn,optional"`
+	RPCLog bool `yaml:"rpc_log,optional,default=false"`
 }
 
 func enumUnmarshal(u func(interface{}, bool) error, types map[string]interface{}) (interface{}, error) {
@@ -328,7 +373,7 @@ var ConfigFileDefaultLocations = []string{
 	"/usr/local/etc/zrepl/zrepl.yml",
 }
 
-func ParseConfig(path string) (i Config, err error) {
+func ParseConfig(path string) (i *Config, err error) {
 
 	if path == "" {
 		// Try default locations
@@ -352,11 +397,18 @@ func ParseConfig(path string) (i Config, err error) {
 		return
 	}
 
-	if err = yaml.UnmarshalStrict(bytes, &i); err != nil {
-		return
-	}
+	return ParseConfigBytes(bytes)
+}
 
-	return
+func ParseConfigBytes(bytes []byte) (*Config, error) {
+	var c *Config
+	if err := yaml.UnmarshalStrict(bytes, &c); err != nil {
+		return nil, err
+	}
+	if c == nil {
+		return nil, fmt.Errorf("config is empty or only consists of comments")
+	}
+	return c, nil
 }
 
 var durationStringRegex *regexp.Regexp = regexp.MustCompile(`^\s*(\d+)\s*(s|m|h|d|w)\s*$`)
diff --git a/config/config_minimal_test.go b/config/config_minimal_test.go
new file mode 100644
index 0000000..82edde8
--- /dev/null
+++ b/config/config_minimal_test.go
@@ -0,0 +1,41 @@
+package config
+
+import (
+	"testing"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConfigEmptyFails(t *testing.T) {
+	conf, err := testConfig(t, "\n")
+	assert.Nil(t, conf)
+	assert.Error(t, err)
+}
+
+func TestJobsOnlyWorks(t *testing.T) {
+	testValidConfig(t, `
+jobs:
+- name: push
+  type: push
+  # snapshot the filesystems matched by the left-hand-side of the mapping
+  # every 10m with zrepl_ as prefix
+  replication:
+    connect:
+      type: tcp
+      address: localhost:2342
+    filesystems: {
+      "pool1/var/db<": true,
+      "pool1/usr/home<": true,
+      "pool1/usr/home/paranoid": false, #don't backup paranoid user
+      "pool1/poudriere/ports<": false #don't backup the ports trees
+    }
+  snapshotting:
+    snapshot_prefix: zrepl_
+    interval: 10m
+  pruning:
+    keep_sender:
+    - type: not_replicated
+    keep_receiver:
+    - type: last_n 
+      count: 1
+`)
+}
\ No newline at end of file
diff --git a/config/config_rpc_test.go b/config/config_rpc_test.go
new file mode 100644
index 0000000..0fd2a4c
--- /dev/null
+++ b/config/config_rpc_test.go
@@ -0,0 +1,61 @@
+package config
+
+import (
+	"testing"
+	"github.com/stretchr/testify/assert"
+	"time"
+)
+
+func TestRPC (t *testing.T) {
+	conf := testValidConfig(t, `
+jobs:
+- name: pull_servers
+  type: pull
+  replication:
+    connect:
+      type: tcp
+      address: "server1.foo.bar:8888"
+      rpc:
+        timeout: 20s # different form default, should merge
+    root_dataset: "pool2/backup_servers"
+    interval: 10m
+  pruning:
+    keep_sender:
+      - type: not_replicated
+    keep_receiver:
+      - type: last_n
+        count: 100
+
+- name: pull_servers2
+  type: pull
+  replication:
+    connect:
+      type: tcp
+      address: "server1.foo.bar:8888"
+      rpc:
+        tx_chunk_size: 0xabcd # different from default, should merge
+    root_dataset: "pool2/backup_servers"
+    interval: 10m
+  pruning:
+    keep_sender:
+    - type: not_replicated
+    keep_receiver:
+    - type: last_n
+      count: 100
+`)
+
+	assert.Equal(t, 20*time.Second, conf.Jobs[0].Ret.(*PullJob).Replication.Connect.Ret.(*TCPConnect).RPC.Timeout)
+	assert.Equal(t, uint(0xabcd), conf.Jobs[1].Ret.(*PullJob).Replication.Connect.Ret.(*TCPConnect).RPC.TxChunkSize)
+	defConf := RPCConfig{}
+	Default(&defConf)
+	assert.Equal(t, defConf.Timeout, conf.Global.RPC.Timeout)
+}
+
+func TestGlobal_DefaultRPCConfig(t *testing.T) {
+	assert.NotPanics(t, func() {
+		var c RPCConfig
+		Default(&c)
+		assert.NotNil(t, c)
+		assert.Equal(t, c.TxChunkSize, uint(1)<<15)
+	})
+}
diff --git a/config/config_test.go b/config/config_test.go
index ad975d0..64a12f9 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -4,6 +4,9 @@ import (
 	"github.com/kr/pretty"
 	"path/filepath"
 	"testing"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/zrepl/yaml-config"
 )
 
 func TestSampleConfigsAreParsedWithoutErrors(t *testing.T) {
@@ -27,3 +30,26 @@ func TestSampleConfigsAreParsedWithoutErrors(t *testing.T) {
 	}
 
 }
+
+func TestLoggingOutletEnumList_SetDefaults(t *testing.T) {
+	e := &LoggingOutletEnumList{}
+	var i yaml.Defaulter = e
+	require.NotPanics(t, func() {
+		i.SetDefault()
+		assert.Equal(t, "warn", (*e)[0].Ret.(StdoutLoggingOutlet).Level)
+	})
+}
+
+
+func testValidConfig(t *testing.T, input string) (*Config) {
+	t.Helper()
+	conf, err := testConfig(t, input)
+	require.NoError(t, err)
+	require.NotNil(t, conf)
+	return conf
+}
+
+func testConfig(t *testing.T, input string) (*Config, error) {
+	t.Helper()
+	return ParseConfigBytes([]byte(input))
+}
\ No newline at end of file
diff --git a/daemon/connecter/connecter.go b/daemon/connecter/connecter.go
index a27ba7d..a5d95ad 100644
--- a/daemon/connecter/connecter.go
+++ b/daemon/connecter/connecter.go
@@ -6,7 +6,7 @@ import (
 	"github.com/zrepl/zrepl/config"
 )
 
-func FromConfig(g config.Global, in config.ConnectEnum) (streamrpc.Connecter, error) {
+func FromConfig(g *config.Global, in config.ConnectEnum) (streamrpc.Connecter, error) {
 	switch v := in.Ret.(type) {
 	case *config.SSHStdinserverConnect:
 		return SSHStdinserverConnecterFromConfig(v)
diff --git a/daemon/daemon.go b/daemon/daemon.go
index e231d72..078f1f4 100644
--- a/daemon/daemon.go
+++ b/daemon/daemon.go
@@ -17,7 +17,7 @@ import (
 	"time"
 )
 
-func Run(conf config.Config) error {
+func Run(conf *config.Config) error {
 
 	ctx, cancel := context.WithCancel(context.Background())
 
@@ -29,7 +29,7 @@ func Run(conf config.Config) error {
 		cancel()
 	}()
 
-	outlets, err := logging.OutletsFromConfig(conf.Global.Logging)
+	outlets, err := logging.OutletsFromConfig(*conf.Global.Logging)
 	if err != nil {
 		return errors.Wrap(err, "cannot build logging from config")
 	}
diff --git a/daemon/job/build_jobs.go b/daemon/job/build_jobs.go
index 8843b55..b438cac 100644
--- a/daemon/job/build_jobs.go
+++ b/daemon/job/build_jobs.go
@@ -6,7 +6,7 @@ import (
 	"github.com/pkg/errors"
 )
 
-func JobsFromConfig(c config.Config) ([]Job, error) {
+func JobsFromConfig(c *config.Config) ([]Job, error) {
 	js := make([]Job, len(c.Jobs))
 	for i := range c.Jobs {
 		j, err := buildJob(c.Global, c.Jobs[i])
@@ -18,7 +18,7 @@ func JobsFromConfig(c config.Config) ([]Job, error) {
 	return js, nil
 }
 
-func buildJob(c config.Global, in config.JobEnum) (j Job, err error) {
+func buildJob(c *config.Global, in config.JobEnum) (j Job, err error) {
 	switch v := in.Ret.(type) {
 	case *config.SinkJob:
 		j, err = SinkFromConfig(c, v)
diff --git a/daemon/job/push.go b/daemon/job/push.go
index e4750c2..088e863 100644
--- a/daemon/job/push.go
+++ b/daemon/job/push.go
@@ -25,7 +25,7 @@ type Push struct {
 	replication *replication.Replication
 }
 
-func PushFromConfig(g config.Global, in *config.PushJob) (j *Push, err error) {
+func PushFromConfig(g *config.Global, in *config.PushJob) (j *Push, err error) {
 
 	j = &Push{}
 	j.name = in.Name
diff --git a/daemon/job/sink.go b/daemon/job/sink.go
index 8c9f496..3c20ae3 100644
--- a/daemon/job/sink.go
+++ b/daemon/job/sink.go
@@ -19,7 +19,7 @@ type Sink struct {
 	fsmapInv endpoint.FSFilter
 }
 
-func SinkFromConfig(g config.Global, in *config.SinkJob) (s *Sink, err error) {
+func SinkFromConfig(g *config.Global, in *config.SinkJob) (s *Sink, err error) {
 
 	// FIXME multi client support
 
diff --git a/daemon/logging/build_logging.go b/daemon/logging/build_logging.go
index 9d88d41..fbaf9c2 100644
--- a/daemon/logging/build_logging.go
+++ b/daemon/logging/build_logging.go
@@ -16,7 +16,7 @@ import (
 	"os"
 )
 
-func OutletsFromConfig(in []config.LoggingOutletEnum) (*logger.Outlets, error) {
+func OutletsFromConfig(in config.LoggingOutletEnumList) (*logger.Outlets, error) {
 
 	outlets := logger.NewOutlets()
 
diff --git a/daemon/serve/serve.go b/daemon/serve/serve.go
index 8ab7945..4df8488 100644
--- a/daemon/serve/serve.go
+++ b/daemon/serve/serve.go
@@ -10,7 +10,7 @@ type ListenerFactory interface {
 	Listen() (net.Listener, error)
 }
 
-func FromConfig(g config.Global, in config.ServeEnum) (ListenerFactory, error) {
+func FromConfig(g *config.Global, in config.ServeEnum) (ListenerFactory, error) {
 
 	switch v := in.Ret.(type) {
 	case *config.TCPServe:
diff --git a/daemon/serve/serve_stdinserver.go b/daemon/serve/serve_stdinserver.go
index 4048d65..f6403d3 100644
--- a/daemon/serve/serve_stdinserver.go
+++ b/daemon/serve/serve_stdinserver.go
@@ -15,7 +15,7 @@ type StdinserverListenerFactory struct {
 	sockpath       string
 }
 
-func StdinserverListenerFactoryFromConfig(g config.Global, in *config.StdinserverServer) (f *StdinserverListenerFactory, err error) {
+func StdinserverListenerFactoryFromConfig(g *config.Global, in *config.StdinserverServer) (f *StdinserverListenerFactory, err error) {
 
 	f = &StdinserverListenerFactory{
 		ClientIdentity: in.ClientIdentity,
diff --git a/daemon/serve/serve_tcp.go b/daemon/serve/serve_tcp.go
index a5bad28..21cab59 100644
--- a/daemon/serve/serve_tcp.go
+++ b/daemon/serve/serve_tcp.go
@@ -9,7 +9,7 @@ type TCPListenerFactory struct {
 	Address string
 }
 
-func TCPListenerFactoryFromConfig(c config.Global, in *config.TCPServe) (*TCPListenerFactory, error) {
+func TCPListenerFactoryFromConfig(c *config.Global, in *config.TCPServe) (*TCPListenerFactory, error) {
 	lf := &TCPListenerFactory{
 		Address: in.Listen,
 	}
diff --git a/daemon/serve/serve_tls.go b/daemon/serve/serve_tls.go
index f24f5ad..0b80345 100644
--- a/daemon/serve/serve_tls.go
+++ b/daemon/serve/serve_tls.go
@@ -18,7 +18,7 @@ type TLSListenerFactory struct {
 	handshakeTimeout time.Duration
 }
 
-func TLSListenerFactoryFromConfig(c config.Global, in *config.TLSServe) (lf *TLSListenerFactory, err error) {
+func TLSListenerFactoryFromConfig(c *config.Global, in *config.TLSServe) (lf *TLSListenerFactory, err error) {
 	lf = &TLSListenerFactory{
 		address: in.Listen,
 	}