Kernels higher than 2.6.10 don't support multiple --to arguments in
DNAT and SNAT targets. At present, the error is somewhat vague:
# iptables -t nat -A foo -j SNAT --to 1.2.3.4 --to 2.3.4.5
iptables: Invalid argument
But if we want current iptables to work with kernels <= 2.6.10, we
cannot simply disallow this in all cases.
So the below patch adds kernel version checking to iptables, and
utilizes it in [DS]NAT. Now, users will see a more informative error:
# iptables -t nat -A foo -j SNAT --to 1.2.3.4 --to 2.3.4.5
iptables v1.3.3: Multiple --to-source not supported
This generic infrastructure (shamelessly lifted from procps btw) may
come in handy in the future for other changes.
This fixes bugzilla #367. (Phil Oester)
diff --git a/include/iptables.h b/include/iptables.h
index f0cad8d..fbcf2eb 100644
--- a/include/iptables.h
+++ b/include/iptables.h
@@ -175,4 +175,13 @@
iptc_handle_t *handle);
extern int for_each_chain(int (*fn)(const ipt_chainlabel, int, iptc_handle_t *),
int verbose, int builtinstoo, iptc_handle_t *handle);
+
+/* kernel revision handling */
+extern int kernel_version;
+extern void get_kernel_version(void);
+#define LINUX_VERSION(x,y,z) (0x10000*(x) + 0x100*(y) + z)
+#define LINUX_VERSION_MAJOR(x) (((x)>>16) & 0xFF)
+#define LINUX_VERSION_MINOR(x) (((x)>> 8) & 0xFF)
+#define LINUX_VERSION_PATCH(x) ( (x) & 0xFF)
+
#endif /*_IPTABLES_USER_H*/