Don't limit iptables connection tracking to TCP protocol; allow connection tracking for all protocols. This allows services like NTP, which is UDP-based, to receive replies from an NTP server even if the port is blocked, as long as it is in reply to a request sent from the device itself.
I found that with IPv4Network types, calling list(ip_ntwrk.hosts()) is reliable. However, when doing the same with an IPv6Network, I found that the conversion to a list can hang indefinitely. This appears to me to be a bug in the ipaddress.IPv6Network implementation. However, I could not find any other reports on the web.
This patch changes the behavior to call next() on the ip_ntwrk.hosts() generator instead, which returns the IP address of the first host.
Since the introduction of VRF, interface-related tables in ConfigDB will have multiple entries, one of which only contains the interface name and no IP prefix. Thus, when iterating over the keys in the tables, we need to ignore the entries which do not contain IP prefixes.
Modified caclmgrd behavior to enhance control plane security as follows:
Upon starting or receiving notification of ACL table/rule changes in Config DB:
1. Add iptables/ip6tables commands to allow all incoming packets from established TCP sessions or new TCP sessions which are related to established TCP sessions
2. Add iptables/ip6tables commands to allow bidirectional ICMPv4 ping and traceroute
3. Add iptables/ip6tables commands to allow bidirectional ICMPv6 ping and traceroute
4. Add iptables/ip6tables commands to allow all incoming Neighbor Discovery Protocol (NDP) NS/NA/RS/RA messages
5. Add iptables/ip6tables commands to allow all incoming IPv4 DHCP packets
6. Add iptables/ip6tables commands to allow all incoming IPv6 DHCP packets
7. Add iptables/ip6tables commands to allow all incoming BGP traffic
8. Add iptables/ip6tables commands for all ACL rules for recognized services (currently SSH, SNMP, NTP)
9. For all services which we did not find configured ACL rules, add iptables/ip6tables commands to allow all incoming packets for those services (allows the device to accept SSH connections before the device is configured)
10. Add iptables rules to drop all packets destined for loopback interface IP addresses
11. Add iptables rules to drop all packets destined for management interface IP addresses
12. Add iptables rules to drop all packets destined for point-to-point interface IP addresses
13. Add iptables rules to drop all packets destined for our VLAN interface gateway IP addresses
14. Add iptables/ip6tables commands to allow all incoming packets with TTL of 0 or 1 (This allows the device to respond to tools like tcptraceroute)
15. If we found control plane ACLs in the configuration and applied them, we lastly add iptables/ip6tables commands to drop all other incoming packets
* [caclmgrd] Heuristically determine whether ACL is IPv4 or IPv6, use iptables/ip6tables accordingly
* Check all rules in table until we find one with a SRC_IP
- Move all minigraph-related action from rc.local to updategraph
- updategraph service is now after database. All feature services are now after and depending on updategraph
