The neighbour table establishes bindings between protocol addresses and link layer addresses for hosts sharing the same physical link. More...

Functions
int	rtnl_neigh_parse (struct nlmsghdr n, struct rtnl_neigh *result)

Neighbour States Translations
char *	rtnl_neigh_state2str (int state, char *buf, size_t len)

int	rtnl_neigh_str2state (const char *name)

Neighbour Flags Translations
char *	rtnl_neigh_flags2str (int flags, char *buf, size_t len)

int	rtnl_neigh_str2flag (const char *name)

Neighbour Object Allocation/Freeage
struct rtnl_neigh *	rtnl_neigh_alloc (void)

void	rtnl_neigh_put (struct rtnl_neigh *neigh)

Neighbour Cache Managament
int	rtnl_neigh_alloc_cache (struct nl_sock sock, struct nl_cache *result)
	Build a neighbour cache including all neighbours currently configured in the kernel. More...

int	rtnl_neigh_alloc_cache_flags (struct nl_sock sock, struct nl_cache *result, unsigned int flags)
	Build a neighbour cache including all neighbours currently configured in the kernel. More...

struct rtnl_neigh *	rtnl_neigh_get (struct nl_cache cache, int ifindex, struct nl_addr dst)
	Look up a neighbour by interface index and destination address. More...

struct rtnl_neigh *	rtnl_neigh_get_by_vlan (struct nl_cache cache, int ifindex, struct nl_addr lladdr, int vlan)
	Look up a neighbour by interface index, link layer address and vlan id. More...

Neighbour Addition
int	rtnl_neigh_build_add_request (struct rtnl_neigh tmpl, int flags, struct nl_msg *result)
	Build netlink request message to add a new neighbour. More...

int	rtnl_neigh_add (struct nl_sock sk, struct rtnl_neigh tmpl, int flags)
	Add a new neighbour. More...

Neighbour Deletion
int	rtnl_neigh_build_delete_request (struct rtnl_neigh neigh, int flags, struct nl_msg *result)
	Build a netlink request message to delete a neighbour. More...

int	rtnl_neigh_delete (struct nl_sock sk, struct rtnl_neigh neigh, int flags)
	Delete a neighbour. More...

Attributes
void	rtnl_neigh_set_state (struct rtnl_neigh *neigh, int state)

int	rtnl_neigh_get_state (struct rtnl_neigh *neigh)

void	rtnl_neigh_unset_state (struct rtnl_neigh *neigh, int state)

void	rtnl_neigh_set_flags (struct rtnl_neigh *neigh, unsigned int flags)

unsigned int	rtnl_neigh_get_flags (struct rtnl_neigh *neigh)

void	rtnl_neigh_unset_flags (struct rtnl_neigh *neigh, unsigned int flags)

void	rtnl_neigh_set_ifindex (struct rtnl_neigh *neigh, int ifindex)

int	rtnl_neigh_get_ifindex (struct rtnl_neigh *neigh)

void	rtnl_neigh_set_lladdr (struct rtnl_neigh neigh, struct nl_addr addr)

struct nl_addr *	rtnl_neigh_get_lladdr (struct rtnl_neigh *neigh)

int	rtnl_neigh_set_dst (struct rtnl_neigh neigh, struct nl_addr addr)

struct nl_addr *	rtnl_neigh_get_dst (struct rtnl_neigh *neigh)

void	rtnl_neigh_set_family (struct rtnl_neigh *neigh, int family)

int	rtnl_neigh_get_family (struct rtnl_neigh *neigh)

void	rtnl_neigh_set_type (struct rtnl_neigh *neigh, int type)

int	rtnl_neigh_get_type (struct rtnl_neigh *neigh)

void	rtnl_neigh_set_vlan (struct rtnl_neigh *neigh, int vlan)

int	rtnl_neigh_get_vlan (struct rtnl_neigh *neigh)

void	rtnl_neigh_set_master (struct rtnl_neigh *neigh, int ifindex)

int	rtnl_neigh_get_master (struct rtnl_neigh *neigh)

Detailed Description

The neighbour table establishes bindings between protocol addresses and link layer addresses for hosts sharing the same physical link.

This module allows you to access and manipulate the content of these tables.

Neighbour States: NUD_INCOMPLETE

NUD_REACHABLE

NUD_STALE

NUD_DELAY

NUD_PROBE

NUD_FAILED

NUD_NOARP

NUD_PERMANENT

Neighbour Flags: NTF_USE

NTF_PROXY

NTF_ROUTER

NTF_SELF

Neighbour Identification

A neighbour is uniquely identified by the attributes listed below, whenever you refer to an existing neighbour all of the attributes must be set. Neighbours from caches automatically have all required attributes set.

interface index (rtnl_neigh_set_ifindex())
destination address (rtnl_neigh_set_dst())

Changeable Attributes

state (rtnl_neigh_set_state())
link layer address (rtnl_neigh_set_lladdr())

Required Caches for Dumping

In order to dump neighbour attributes you must provide the following caches via nl_cache_provide()

link cache holding all links

TODO

Document proxy settings
Document states and their influence

1) Retrieving information about configured neighbours: // The first step is to retrieve a list of all available neighbour within

// the kernel and put them into a cache.

struct nl_cache *cache = rtnl_neigh_alloc_cache(sk);

// Neighbours can then be looked up by the interface and destination

// address:

struct rtnl_neigh *neigh = rtnl_neigh_get(cache, ifindex, dst_addr);

// After successful usage, the object must be given back to the cache

rtnl_neigh_put(neigh);

rtnl_neigh_alloc_cache
int rtnl_neigh_alloc_cache(struct nl_sock *sock, struct nl_cache **result)
Build a neighbour cache including all neighbours currently configured in the kernel.
Definition: neigh.c:590

rtnl_neigh_get
struct rtnl_neigh * rtnl_neigh_get(struct nl_cache *cache, int ifindex, struct nl_addr *dst)
Look up a neighbour by interface index and destination address.
Definition: neigh.c:635

2) Adding new neighbours: // Allocate an empty neighbour handle to be filled out with the attributes

// of the new neighbour.

struct rtnl_neigh *neigh = rtnl_neigh_alloc();

// Fill out the attributes of the new neighbour

rtnl_neigh_set_ifindex(neigh, ifindex);

rtnl_neigh_set_dst(neigh, dst_addr);

rtnl_neigh_set_state(neigh, rtnl_neigh_str2state("permanent"));

// Build the netlink message and send it to the kernel, the operation will

// block until the operation has been completed. Alternatively the required

// netlink message can be built using rtnl_neigh_build_add_request()

// to be sent out using nl_send_auto_complete().

rtnl_neigh_add(sk, neigh, NLM_F_CREATE);

// Free the memory

rtnl_neigh_put(neigh);

rtnl_neigh_add
int rtnl_neigh_add(struct nl_sock *sk, struct rtnl_neigh *tmpl, int flags)
Add a new neighbour.
Definition: neigh.c:776

3) Deleting an existing neighbour: // Allocate an empty neighbour object to be filled out with the attributes

// matching the neighbour to be deleted. Alternatively a fully equipped

// neighbour object out of a cache can be used instead.

struct rtnl_neigh *neigh = rtnl_neigh_alloc();

// Neighbours are uniquely identified by their interface index and

// destination address, you may fill out other attributes but they

// will have no influence.

rtnl_neigh_set_ifindex(neigh, ifindex);

rtnl_neigh_set_dst(neigh, dst_addr);

// Build the netlink message and send it to the kernel, the operation will

// block until the operation has been completed. Alternatively the required

// netlink message can be built using rtnl_neigh_build_delete_request()

// to be sent out using nl_send_auto_complete().

rtnl_neigh_delete(sk, neigh, 0);

// Free the memory

rtnl_neigh_put(neigh);

rtnl_neigh_delete
int rtnl_neigh_delete(struct nl_sock *sk, struct rtnl_neigh *neigh, int flags)
Delete a neighbour.
Definition: neigh.c:831

4) Changing neighbour attributes: // Allocate an empty neighbour object to be filled out with the attributes

// matching the neighbour to be changed and the new parameters. Alternatively

// a fully equipped modified neighbour object out of a cache can be used.

struct rtnl_neigh *neigh = rtnl_neigh_alloc();

// Identify the neighbour to be changed by its interface index and

// destination address

rtnl_neigh_set_ifindex(neigh, ifindex);

rtnl_neigh_set_dst(neigh, dst_addr);

// The link layer address may be modified, if so it is wise to change

// its state to "permanent" in order to avoid having it overwritten.

rtnl_neigh_set_lladdr(neigh, lladdr);

// Secondly the state can be modified allowing normal neighbours to be

// converted into permanent entries or to manually confirm a neighbour.

rtnl_neigh_set_state(neigh, state);

// Build the netlink message and send it to the kernel, the operation will

// block until the operation has been completed. Alternatively the required

// netlink message can be built using rtnl_neigh_build_change_request()

// to be sent out using nl_send_auto_complete().

rtnl_neigh_add(sk, neigh, NLM_F_REPLACE);

// Free the memory

rtnl_neigh_put(neigh);

Function Documentation

◆ rtnl_neigh_parse()

int rtnl_neigh_parse	(	struct nlmsghdr *	n,
		struct rtnl_neigh **	result
	)

Definition at line 349 of file neigh.c.

◆ rtnl_neigh_alloc()

struct rtnl_neigh * rtnl_neigh_alloc ( void )

Definition at line 563 of file neigh.c.

◆ rtnl_neigh_put()

void rtnl_neigh_put ( struct rtnl_neigh * neigh )

Definition at line 568 of file neigh.c.

◆ rtnl_neigh_alloc_cache()

int rtnl_neigh_alloc_cache	(	struct nl_sock *	sock,
		struct nl_cache **	result
	)

Build a neighbour cache including all neighbours currently configured in the kernel.

Parameters

sock	Netlink socket.
result	Pointer to store resulting cache.

Allocates a new neighbour cache, initializes it properly and updates it to include all neighbours currently configured in the kernel.

Returns: 0 on success or a negative error code.

Definition at line 590 of file neigh.c.

References nl_cache_alloc_and_fill().

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◆ rtnl_neigh_alloc_cache_flags()

int rtnl_neigh_alloc_cache_flags	(	struct nl_sock *	sock,
		struct nl_cache **	result,
		unsigned int	flags
	)

Build a neighbour cache including all neighbours currently configured in the kernel.

Parameters

sock	Netlink socket.
result	Pointer to store resulting cache.
flags	Flags to apply to cache before filling

Allocates a new neighbour cache, initializes it properly and updates it to include all neighbours currently configured in the kernel.

Returns: 0 on success or a negative error code.

Definition at line 606 of file neigh.c.

References nl_cache_alloc(), nl_cache_free(), nl_cache_refill(), and nl_cache_set_flags().

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◆ rtnl_neigh_get()

struct rtnl_neigh * rtnl_neigh_get	(	struct nl_cache *	cache,
		int	ifindex,
		struct nl_addr *	dst
	)

Look up a neighbour by interface index and destination address.

Parameters

cache	neighbour cache
ifindex	interface index the neighbour is on
dst	destination address of the neighbour

Returns: neighbour handle or NULL if no match was found.

Definition at line 635 of file neigh.c.

References nl_addr_cmp(), and nl_object_get().

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◆ rtnl_neigh_get_by_vlan()

struct rtnl_neigh * rtnl_neigh_get_by_vlan	(	struct nl_cache *	cache,
		int	ifindex,
		struct nl_addr *	lladdr,
		int	vlan
	)

Look up a neighbour by interface index, link layer address and vlan id.

Parameters

cache	neighbour cache
ifindex	interface index the neighbour is on
lladdr	link layer address of the neighbour
vlan	vlan id of the neighbour

Returns: neighbour handle or NULL if no match was found.

Definition at line 661 of file neigh.c.

References nl_addr_cmp(), and nl_object_get().

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◆ rtnl_neigh_build_add_request()

int rtnl_neigh_build_add_request	(	struct rtnl_neigh *	tmpl,
		int	flags,
		struct nl_msg **	result
	)

Build netlink request message to add a new neighbour.

Parameters

tmpl	template with data of new neighbour
flags	additional netlink message flags
result	Pointer to store resulting message.

Builds a new netlink message requesting a addition of a new neighbour. The netlink message header isn't fully equipped with all relevant fields and must thus be sent out via nl_send_auto_complete() or supplemented as needed. tmpl must contain the attributes of the new neighbour set via rtnl_neigh_set_* functions.

The following attributes must be set in the template:

Interface index (rtnl_neigh_set_ifindex())
State (rtnl_neigh_set_state())
Destination address (rtnl_neigh_set_dst())
Link layer address (rtnl_neigh_set_lladdr())

Returns: 0 on success or a negative error code.

Definition at line 752 of file neigh.c.

Referenced by rtnl_neigh_add().

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◆ rtnl_neigh_add()

int rtnl_neigh_add	(	struct nl_sock *	sk,
		struct rtnl_neigh *	tmpl,
		int	flags
	)

Add a new neighbour.

Parameters

sk	Netlink socket.
tmpl	template with requested changes
flags	additional netlink message flags

Builds a netlink message by calling rtnl_neigh_build_add_request(), sends the request to the kernel and waits for the next ACK to be received and thus blocks until the request has been fullfilled.

The following attributes must be set in the template:

Interface index (rtnl_neigh_set_ifindex())
State (rtnl_neigh_set_state())
Destination address (rtnl_neigh_set_dst())
Link layer address (rtnl_neigh_set_lladdr())

Returns: 0 on success or a negative error if an error occured.

Definition at line 776 of file neigh.c.

References nl_send_auto_complete(), nlmsg_free(), and rtnl_neigh_build_add_request().

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◆ rtnl_neigh_build_delete_request()

int rtnl_neigh_build_delete_request	(	struct rtnl_neigh *	neigh,
		int	flags,
		struct nl_msg **	result
	)

Build a netlink request message to delete a neighbour.

Parameters

neigh	neighbour to delete
flags	additional netlink message flags
result	Pointer to store resulting message.

Builds a new netlink message requesting a deletion of a neighbour. The netlink message header isn't fully equipped with all relevant fields and must thus be sent out via nl_send_auto_complete() or supplemented as needed. neigh must point to an existing neighbour.

Returns: 0 on success or a negative error code.

Definition at line 813 of file neigh.c.

Referenced by rtnl_neigh_delete().

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◆ rtnl_neigh_delete()

int rtnl_neigh_delete	(	struct nl_sock *	sk,
		struct rtnl_neigh *	neigh,
		int	flags
	)

Delete a neighbour.

Parameters

sk	Netlink socket.
neigh	neighbour to delete
flags	additional netlink message flags

Builds a netlink message by calling rtnl_neigh_build_delete_request(), sends the request to the kernel and waits for the next ACK to be received and thus blocks until the request has been fullfilled.

Returns: 0 on success or a negative error if an error occured.

Definition at line 831 of file neigh.c.

References nl_send_auto_complete(), nlmsg_free(), and rtnl_neigh_build_delete_request().

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◆ rtnl_neigh_state2str()

char * rtnl_neigh_state2str	(	int	state,
		char *	buf,
		size_t	len
	)

Definition at line 871 of file neigh.c.

◆ rtnl_neigh_str2state()

int rtnl_neigh_str2state ( const char * name )

Definition at line 877 of file neigh.c.

◆ rtnl_neigh_flags2str()

char * rtnl_neigh_flags2str	(	int	flags,
		char *	buf,
		size_t	len
	)

Definition at line 899 of file neigh.c.

◆ rtnl_neigh_str2flag()

int rtnl_neigh_str2flag ( const char * name )

Definition at line 905 of file neigh.c.

◆ rtnl_neigh_set_state()

void rtnl_neigh_set_state	(	struct rtnl_neigh *	neigh,
		int	state
	)

Definition at line 917 of file neigh.c.

◆ rtnl_neigh_get_state()

int rtnl_neigh_get_state ( struct rtnl_neigh * neigh )

Definition at line 924 of file neigh.c.

◆ rtnl_neigh_unset_state()

void rtnl_neigh_unset_state	(	struct rtnl_neigh *	neigh,
		int	state
	)

Definition at line 932 of file neigh.c.

◆ rtnl_neigh_set_flags()

void rtnl_neigh_set_flags	(	struct rtnl_neigh *	neigh,
		unsigned int	flags
	)

Definition at line 939 of file neigh.c.

◆ rtnl_neigh_get_flags()

unsigned int rtnl_neigh_get_flags ( struct rtnl_neigh * neigh )

Definition at line 946 of file neigh.c.

◆ rtnl_neigh_unset_flags()

void rtnl_neigh_unset_flags	(	struct rtnl_neigh *	neigh,
		unsigned int	flags
	)

Definition at line 951 of file neigh.c.

◆ rtnl_neigh_set_ifindex()

void rtnl_neigh_set_ifindex	(	struct rtnl_neigh *	neigh,
		int	ifindex
	)

Definition at line 958 of file neigh.c.

◆ rtnl_neigh_get_ifindex()

int rtnl_neigh_get_ifindex ( struct rtnl_neigh * neigh )

Definition at line 964 of file neigh.c.

◆ rtnl_neigh_set_lladdr()

void rtnl_neigh_set_lladdr	(	struct rtnl_neigh *	neigh,
		struct nl_addr *	addr
	)

Definition at line 993 of file neigh.c.

◆ rtnl_neigh_get_lladdr()

struct nl_addr * rtnl_neigh_get_lladdr ( struct rtnl_neigh * neigh )

Definition at line 998 of file neigh.c.

◆ rtnl_neigh_set_dst()

int rtnl_neigh_set_dst	(	struct rtnl_neigh *	neigh,
		struct nl_addr *	addr
	)

Definition at line 1006 of file neigh.c.

◆ rtnl_neigh_get_dst()

struct nl_addr * rtnl_neigh_get_dst ( struct rtnl_neigh * neigh )

Definition at line 1012 of file neigh.c.

◆ rtnl_neigh_set_family()

void rtnl_neigh_set_family	(	struct rtnl_neigh *	neigh,
		int	family
	)

Definition at line 1020 of file neigh.c.

◆ rtnl_neigh_get_family()

int rtnl_neigh_get_family ( struct rtnl_neigh * neigh )

Definition at line 1026 of file neigh.c.

◆ rtnl_neigh_set_type()

void rtnl_neigh_set_type	(	struct rtnl_neigh *	neigh,
		int	type
	)

Definition at line 1031 of file neigh.c.

◆ rtnl_neigh_get_type()

int rtnl_neigh_get_type ( struct rtnl_neigh * neigh )

Definition at line 1037 of file neigh.c.

◆ rtnl_neigh_set_vlan()

void rtnl_neigh_set_vlan	(	struct rtnl_neigh *	neigh,
		int	vlan
	)

Definition at line 1045 of file neigh.c.

◆ rtnl_neigh_get_vlan()

int rtnl_neigh_get_vlan ( struct rtnl_neigh * neigh )

Definition at line 1051 of file neigh.c.

◆ rtnl_neigh_set_master()

void rtnl_neigh_set_master	(	struct rtnl_neigh *	neigh,
		int	ifindex
	)

Definition at line 1059 of file neigh.c.

◆ rtnl_neigh_get_master()

int rtnl_neigh_get_master ( struct rtnl_neigh * neigh )

Definition at line 1065 of file neigh.c.

Functions

Neighbour States Translations

Neighbour Flags Translations

Neighbour Object Allocation/Freeage

Neighbour Cache Managament

Neighbour Addition

Neighbour Deletion

Attributes

Detailed Description

Function Documentation

◆ rtnl_neigh_parse()

◆ rtnl_neigh_alloc()

◆ rtnl_neigh_put()

◆ rtnl_neigh_alloc_cache()

◆ rtnl_neigh_alloc_cache_flags()

◆ rtnl_neigh_get()

◆ rtnl_neigh_get_by_vlan()

◆ rtnl_neigh_build_add_request()

◆ rtnl_neigh_add()

◆ rtnl_neigh_build_delete_request()

◆ rtnl_neigh_delete()

◆ rtnl_neigh_state2str()

◆ rtnl_neigh_str2state()

◆ rtnl_neigh_flags2str()

◆ rtnl_neigh_str2flag()

◆ rtnl_neigh_set_state()

◆ rtnl_neigh_get_state()

◆ rtnl_neigh_unset_state()

◆ rtnl_neigh_set_flags()

◆ rtnl_neigh_get_flags()

◆ rtnl_neigh_unset_flags()

◆ rtnl_neigh_set_ifindex()

◆ rtnl_neigh_get_ifindex()

◆ rtnl_neigh_set_lladdr()

◆ rtnl_neigh_get_lladdr()

◆ rtnl_neigh_set_dst()

◆ rtnl_neigh_get_dst()

◆ rtnl_neigh_set_family()

◆ rtnl_neigh_get_family()

◆ rtnl_neigh_set_type()

◆ rtnl_neigh_get_type()

◆ rtnl_neigh_set_vlan()

◆ rtnl_neigh_get_vlan()

◆ rtnl_neigh_set_master()

◆ rtnl_neigh_get_master()