doc: fix typo in length manpage
References: http://bugs.debian.org/551867
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/extensions/libxt_length.man b/extensions/libxt_length.man
index e324e03..07b6ea6 100644
--- a/extensions/libxt_length.man
+++ b/extensions/libxt_length.man
@@ -1,5 +1,5 @@
This module matches the length of the layer-3 payload (e.g. layer-4 packet)
-f a packet against a specific value
+of a packet against a specific value
or range of values.
.TP
[\fB!\fP] \fB\-\-length\fP \fIlength\fP[\fB:\fP\fIlength\fP]