bgpd: RFC 5082 Generalized TTL Security Mechanism support
* bgpd: Add support for RFC 5082 GTSM, which allows the TTL field to be used
to verify that incoming packets have been sent from neighbours no more
than X IP hops away. In other words, this allows packets that were sent from
further away (i.e. not by the neighbour with known distance, and so possibly
a miscreant) to be filtered out.
* lib/sockunion.{c,h}: (sockopt_minttl) new function, to set a minimum TTL
using the IP_MINTTL socket opt.
* bgpd.h: (BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK) define for command
error for minttl.
(struct peer) add a config variable, to store the configured minttl.
(peer_ttl_security_hops_{set,unset}) configuration handlers
* bgpd.c: (peer_group_get) init gtsm_hops
(peer_ebgp_multihop_{un,}set) check for conflicts with GTSM. Multihop and
GTSM can't both be active for a peer at the same time.
(peer_ttl_security_hops_set) set minttl, taking care to avoid conflicts with
ebgp_multihop.
(bgp_config_write_peer) write out minttl as "neighbor .. ttl-security hops X".
* bgp_vty.c: (bgp_vty_return) message for
BGP_ERR_NO_EBGP_MULTIHOP_WITH_TTLHACK
(peer_ebgp_multihop_{un,}set_vty)
* bgp_network.c: (bgp_accept) set minttl on accepted sockets if appropriate.
(bgp_connect) ditto for outbound.
6 files changed