diff --git a/share/securityonion/sosetup.conf b/share/securityonion/sosetup.conf
index 7f2b513..980c34c 100644
--- a/share/securityonion/sosetup.conf
+++ b/share/securityonion/sosetup.conf
@@ -42,7 +42,8 @@ DOMAIN='example.com'
 # For example:
 # SNIFFING_INTERFACES='eth1 eth2'
 SNIFFING_INTERFACES='eth1'
-
+# MTU for sniffing interface(s).  Default is 1550.
+MTU='1550'
 ################################
 # Master Server
 ################################