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@jennifer/routeros

IP addresses

File: src/topics/ip.j. Path: /ip/address (IP_ADDRESS_PATH).

Background

An interface takes part in an IP network by carrying an address with a prefix length: 192.168.88.1/24 means "I am 192.168.88.1, and everything in 192.168.88.0-255 is directly reachable here". The prefix is not decoration - it tells the router how big the network is, so routeros refuses an address without one rather than letting RouterOS guess.

Addresses can be static (you set them) or dynamic (a DHCP client or PPPoE session put them there; those cannot be removed by hand).

Struct

jennifer
mt.IpAddress {
    id,
    address,          # "192.168.88.1/24"
    network,          # "192.168.88.0" - derived by RouterOS
    interfaceName,
    dynamic,          # true: DHCP/PPP assigned it
    disabled, comment
}

Functions

FunctionPurpose
ipAddresses(c) → list of IpAddressevery address, static and dynamic
addIpAddress(c, address, interfaceName) → idassign an address (CIDR required)
removeIpAddress(c, address)remove by exact address string

addIpAddress validates the CIDR via real parsing (ipnet) and checks the interface exists.

Examples

Give the LAN bridge its gateway address:

jennifer
mt.addIpAddress($c, "192.168.88.1/24", "brlan");

List everything with provenance:

jennifer
def addrs as list of mt.IpAddress init mt.ipAddresses($c);
for (def a in $addrs) {
    io.printf("%s on %s dynamic=%t %s\n",
        $a.address, $a.interfaceName, $a.dynamic, $a.comment);
}

Renumber an interface (remove old, add new):

jennifer
mt.removeIpAddress($c, "192.168.88.1/24");
mt.addIpAddress($c, "10.0.10.1/24", "brlan");

Pitfalls

  • The prefix is mandatory. "192.168.88.1" is rejected with a message telling you to write "192.168.88.1/24" - a bare address would otherwise become a /32 with no reachable network.
  • Renumbering the interface your session runs over disconnects you the moment the old address goes; do it from another path (or accept the reconnect).
  • removeIpAddress matches the address string exactly as listed - "192.168.88.1/24", not "192.168.88.1".
  • Dynamic addresses (from dhcp.md WAN or ppp.md) disappear with their session; do not try to manage them here.
  • Two interfaces in the same subnet (overlapping networks) confuse routing; RouterOS allows it, your network will not enjoy it.
  • bridges.md - the LAN address belongs on the bridge.
  • dhcp.md - serve the network you just addressed.
  • routing.md - addresses create "connected" routes automatically.