We can now create and jump in iptables. For example:

$ iptables -N foochain
$ iptables -A INPUT -j foochain

1 files changed, 6 insertions, 3 deletions

diff --git a/pkg/abi/linux/netfilter.go b/pkg/abi/linux/netfilter.go
index bbc4df74c..bd2e13ba1 100644
--- a/pkg/abi/linux/netfilter.go
+++ b/pkg/abi/linux/netfilter.go
@@ -225,11 +225,14 @@ type XTEntryTarget struct {
 // SizeOfXTEntryTarget is the size of an XTEntryTarget.
 const SizeOfXTEntryTarget = 32
 
-// XTStandardTarget is a builtin target, one of ACCEPT, DROP, JUMP, QUEUE, or
-// RETURN. It corresponds to struct xt_standard_target in
+// XTStandardTarget is a built-in target, one of ACCEPT, DROP, JUMP, QUEUE,
+// RETURN, or jump. It corresponds to struct xt_standard_target in
 // include/uapi/linux/netfilter/x_tables.h.
 type XTStandardTarget struct {
-	Target  XTEntryTarget
+	Target XTEntryTarget
+	// A positive verdict indicates a jump, and is the offset from the
+	// start of the table to jump to. A negative value means one of the
+	// other built-in targets.
 	Verdict int32
 	_       [4]byte
 }