diff --git a/metrics/network_io.sh b/metrics/network_io.sh
index 59c7190..f45e695 100644
--- a/metrics/network_io.sh
+++ b/metrics/network_io.sh
@@ -8,12 +8,12 @@ if [ -z $NETWORK_IO_INTERFACE ]; then
   fi
 fi
 
-declare -r __network_io_divisor=$(($INTERVAL*1024))
+declare -r __network_io_divisor=$[$INTERVAL * 1024]
 __network_io_sample=(0 0)
 
 __network_io_calc_kBps() {
   echo $1 $2 | awk -v divisor=$__network_io_divisor \
-        '{printf "%.2f", ($1 - $2) / divisor}'
+                '{printf "%.2f", ($1 - $2) / divisor}'
 }
 
 if is_osx; then
@@ -23,7 +23,8 @@ if is_osx; then
   }
 else
   __network_io_collect () {
-    echo TODO
+    cat /proc/net/dev | awk -v iface_regex="$NETWORK_IO_INTERFACE:" \
+                          '$0 ~ iface_regex {print $2" "$10}'
   }
 fi
 
@@ -38,4 +39,5 @@ collect () {
 
 docs () {
   echo "Network traffic in kB/s."
+  echo "\$NETWORK_IO_INTERFACE=$NETWORK_IO_INTERFACE"
 }
\ No newline at end of file
diff --git a/sysmetricsd.sh b/sysmetricsd.sh
index 4ee847a..84ff1cc 100755
--- a/sysmetricsd.sh
+++ b/sysmetricsd.sh
@@ -56,6 +56,18 @@ for metric in ${__METRICS[@]}; do
   echo
 done
 
+report () {
+  local result
+  if [ -z $2 ]; then
+    label=$metric
+    result="$1"
+  else
+    label="$metric.$1"
+    result="$2"
+  fi
+  __r_${REPORTER}_report $label $result
+}
+
 # collect metrics
 while true; do
   for metric in ${__METRICS[@]}; do
@@ -63,18 +75,6 @@ while true; do
       continue
     fi
 
-    report () {
-      local result
-      if [ -z $2 ]; then
-        label=$metric
-        result="$1"
-      else
-        label="$metric.$1"
-        result="$2"
-      fi
-      __r_${REPORTER}_report $label $result
-    }
-
     __m_${metric}_collect
   done