diff --git a/src/iosource/Component.cc b/src/iosource/Component.cc
index f54c212352..20232161cd 100644
--- a/src/iosource/Component.cc
+++ b/src/iosource/Component.cc
@@ -64,10 +64,9 @@ PktSrcComponent::factory_callback PktSrcComponent::Factory() const
 	return factory;
 	}
 
-
-void PktSrcComponent::Describe(ODesc* d) const
+void PktSrcComponent::DoDescribe(ODesc* d) const
 	{
-	iosource::Component::Describe(d);
+	iosource::Component::DoDescribe(d);
 
 	string prefs;
 
@@ -77,16 +76,16 @@ void PktSrcComponent::Describe(ODesc* d) const
 		if ( prefs.size() )
 			prefs += ", ";
 
-		prefs += *i;
+		prefs += '"' + *i + '"';
 		}
 
-	d->Add(" (interface prefix");
+	d->Add("interface prefix");
 	if ( prefixes.size() > 1 )
 		d->Add("es");
 
-	d->Add(": ");
+	d->Add(" ");
 	d->Add(prefs);
-	d->Add("; ");
+	d->Add("; supports ");
 
 	switch ( type ) {
 	case LIVE:
@@ -105,7 +104,6 @@ void PktSrcComponent::Describe(ODesc* d) const
 		reporter->InternalError("unknown PkrSrc type");
 	}
 
-	d->Add(")");
 	}
 
 PktDumperComponent::PktDumperComponent(const std::string& name, const std::string& arg_prefix, factory_callback arg_factory)
@@ -141,9 +139,9 @@ bool PktDumperComponent::HandlesPrefix(const string& prefix) const
 	return false;
 	}
 
-void PktDumperComponent::Describe(ODesc* d) const
+void PktDumperComponent::DoDescribe(ODesc* d) const
 	{
-	plugin::Component::Describe(d);
+	plugin::Component::DoDescribe(d);
 
 	string prefs;
 
@@ -156,12 +154,11 @@ void PktDumperComponent::Describe(ODesc* d) const
 		prefs += *i;
 		}
 
-	d->Add(" (dumper prefix");
+	d->Add("dumper prefix");
 
 	if ( prefixes.size() > 1 )
 		d->Add("es");
 
 	d->Add(": ");
 	d->Add(prefs);
-	d->Add(")");
 	}
diff --git a/src/iosource/Component.h b/src/iosource/Component.h
index cef500e52f..35e8f612e6 100644
--- a/src/iosource/Component.h
+++ b/src/iosource/Component.h
@@ -93,7 +93,7 @@ public:
 	 * Generates a human-readable description of the component. This goes
 	 * into the output of \c "bro -NN".
 	 */
-	virtual void Describe(ODesc* d) const;
+	virtual void DoDescribe(ODesc* d) const;
 
 private:
 	std::vector<std::string> prefixes;
@@ -140,7 +140,7 @@ public:
 	 * Generates a human-readable description of the component. This goes
 	 * into the output of \c "bro -NN".
 	 */
-	virtual void Describe(ODesc* d) const;
+	virtual void DoDescribe(ODesc* d) const;
 
 private:
 	std::vector<std::string> prefixes;
diff --git a/src/iosource/PktSrc.cc b/src/iosource/PktSrc.cc
index acde8d5ff6..902aaa04be 100644
--- a/src/iosource/PktSrc.cc
+++ b/src/iosource/PktSrc.cc
@@ -89,6 +89,16 @@ double PktSrc::CurrentPacketWallClock()
 
 void PktSrc::Opened(const Properties& arg_props)
 	{
+	if ( arg_props.hdr_size < 0 )
+		{
+		char buf[512];
+		safe_snprintf(buf, sizeof(buf),
+			 "unknown data link type 0x%x", props.link_type);
+		Error(buf);
+		Close();
+		return;
+		}
+
 	props = arg_props;
 	SetClosed(false);
 
@@ -98,6 +108,9 @@ void PktSrc::Opened(const Properties& arg_props)
 		return;
 		}
 
+	if ( props.is_live )
+		Info(fmt("listening on %s, capture length %d bytes\n", props.path.c_str(), SnapLen()));
+
 	DBG_LOG(DBG_PKTIO, "Opened source %s", props.path.c_str());
 	}
 
@@ -433,6 +446,9 @@ bool PktSrc::ExtractNextPacketInternal()
 
 bool PktSrc::PrecompileBPFFilter(int index, const std::string& filter)
 	{
+	if ( index < 0 )
+		return false;
+
 	char errbuf[PCAP_ERRBUF_SIZE];
 
 	// Compile filter.
@@ -465,6 +481,9 @@ bool PktSrc::PrecompileBPFFilter(int index, const std::string& filter)
 
 BPF_Program* PktSrc::GetBPFFilter(int index)
 	{
+	if ( index < 0 )
+		return 0;
+
 	HashKey* hash = new HashKey(HashKey(bro_int_t(index)));
 	BPF_Program* code = filters.Lookup(hash);
 	delete hash;
diff --git a/src/iosource/pcap/Source.cc b/src/iosource/pcap/Source.cc
index 7cca94122b..96e0bb48e5 100644
--- a/src/iosource/pcap/Source.cc
+++ b/src/iosource/pcap/Source.cc
@@ -108,9 +108,8 @@ void PcapSource::OpenLive()
 		return;
 
 	props.is_live = true;
-	Opened(props);
 
-	Info(fmt("listening on %s, capture length %d bytes\n", props.path.c_str(), SnapLen()));
+	Opened(props);
 	}
 
 void PcapSource::OpenOffline()
@@ -264,14 +263,6 @@ void PcapSource::SetHdrSize()
 
 	props.link_type = pcap_datalink(pd);
 	props.hdr_size = GetLinkHeaderSize(props.link_type);
-
-	if ( props.hdr_size < 0 )
-		{
-		safe_snprintf(errbuf, sizeof(errbuf),
-			 "unknown data link type 0x%x", props.link_type);
-		Error(errbuf);
-		Close();
-		}
 	}
 
 iosource::PktSrc* PcapSource::Instantiate(const std::string& path, bool is_live)