-There are a couple of other L2TP imlementations, of which l2tpd is probably the most popular. l2tpd also will handle being either end of a tunnel, and is a lot more configurable than l2tpns. However, due to the way it works, @@ -190,39 +192,47 @@ user, both a primary and a secondary. If either is set to 0.0.0.0, then that one will not be sent. -
BGP routing configuration is entered by the command: @@ -338,6 +356,42 @@ Where peer specifies the BGP neighbour as either a hostname or IP address, as is the remote AS number and keepalive, hold are the timer values in seconds. +
Named access-lists are configured using one of the commands: +
Subsequent lines prefixed with permit or deny +define the body of the access-list. Standard access-list syntax: +
{permit|deny} ip + {host|source source-wildcard|any} + {host|destination destination-wildcard|any} [fragments] +
{permit|deny} udp + {host|source source-wildcard|any} + [{eq|neq|gt|lt} port|range from to] + {host|destination destination-wildcard|any} + [{eq|neq|gt|lt} port|range from to] + [fragments] +
{permit|deny} tcp + {host|source source-wildcard|any} + [{eq|neq|gt|lt} port|range from to] + {host|destination destination-wildcard|any} + [{eq|neq|gt|lt} port|range from to] + [{established|{match-any|match-all} + {+|-}{fin|syn|rst|psh|ack|urg} + ...|fragments] +
| Radius | The ID of the radius request. This is - sent in the packet to the radius server for identification. |
| Radius | The ID of the RADIUS request. This is + sent in the packet to the RADIUS server for identification. |
| State | The state of the request - WAIT, CHAP, AUTH, IPCP, START, STOP, NULL. |
| Session | The session ID that this radius + |
| Session | The session ID that this RADIUS request is associated with |
| Retry | If a response does not appear to the request, it will retry at this time. This is a unix timestamp. |
| Try | Retry count. The radius request is + |
| Try | Retry count. The RADIUS request is discarded after 3 retries. |
@@ -553,7 +607,7 @@ current session for that username will be forwarded to the given host/port. Specify no snoop username to disable interception for the session.
-If you want interception to be permanent, you will have to modify the radius +If you want interception to be permanent, you will have to modify the RADIUS response for the user. See Interception.
If you want throttling to be permanent, you will have to modify the -radius response for the user. See Throttling. +RADIUS response for the user. See Throttling.
@@ -643,14 +697,10 @@ killall -HUP l2tpns The signals understood are:
+
If you wish a session to be throttled permanently, you should set the -Vendor-Specific radius value Cisco-Avpair="throttle=yes", which +Vendor-Specific RADIUS value Cisco-Avpair="throttle=yes", which will be handled by the autothrottle module.
Otherwise, you can enable and disable throttling an active session using @@ -684,7 +734,7 @@ and no snoop username CLI commands. These will enable interception immediately.
If you wish the user to be intercepted whenever they reconnect, you will -need to modify the radius response to include the Vendor-Specific value +need to modify the RADIUS response to include the Vendor-Specific value Cisco-Avpair="intercept=yes". For this feature to be enabled, you need to have the autosnoop module loaded.
@@ -694,11 +744,11 @@ Whenever a session connects, it is not fully set up until authentication is completed. The remote end must send a PPP CHAP or PPP PAP authentication request to l2tpns.
-This request is sent to the radius server, which will hopefully respond with +This request is sent to the RADIUS server, which will hopefully respond with Auth-Accept or Auth-Reject.
If Auth-Accept is received, the session is set up and an IP address is -assigned. The radius server can include a Framed-IP-Address field in the +assigned. The RADIUS server can include a Framed-IP-Address field in the reply, and that address will be assigned to the client. It can also include specific DNS servers, and a Framed-Route if that is required.
@@ -708,7 +758,7 @@ walled garden module is loaded, in which case the user still receives the PPP AUTHACK, but their session is flagged as being a garden'd user, and they should not receive any service.
-The radius reply can also contain a Vendor-Specific attribute called +The RADIUS reply can also contain a Vendor-Specific attribute called Cisco-Avpair. This field is a freeform text field that most Cisco devices understand to contain configuration instructions for the session. In the case of l2tpns it is expected to be of the form @@ -758,7 +808,7 @@ supplied structure:
| Event | Description | Parameters |
|---|---|---|
| pre_auth | -This is called after a radius response has been + | This is called after a RADIUS response has been received, but before it has been processed by the code. This will allow you to modify the response in some way. @@ -775,7 +825,7 @@ supplied structure: |
| post_auth | -This is called after a radius response has been + | This is called after a RADIUS response has been received, and the basic checks have been performed. This is what the garden module uses to force authentication to be accepted. @@ -855,7 +905,7 @@ supplied structure: |
| radius_response | -This is called whenever a radius response includes a + | This is called whenever a RADIUS response includes a
Cisco-Avpair value. The value is split up into
key=value pairs, and each is processed through all
modules.
@@ -901,7 +951,7 @@ Walled Garden is implemented so that you can provide perhaps limited service
to sessions that incorrectly authenticate. Whenever a session provides incorrect authentication, and the -radius server responds with Auth-Reject, the walled garden module +RADIUS server responds with Auth-Reject, the walled garden module (if loaded) will force authentication to succeed, but set the flag garden in the session structure, and adds an iptables rule to the garden_users chain to force all packets for the session's IP @@ -926,6 +976,14 @@ command: iptables -t nat -L garden -nvx + Filtering+ +Sessions may be filtered by specifying Filter-Id attributes in +the RADIUS reply. filter.in specifies that the named +access-list filter should be applied to traffic from the +customer, filter.out specifies a list for traffic to the +customer. +ClusteringAn l2tpns cluster consists of of one* or more servers configured with @@ -973,6 +1031,22 @@ ibgp" for IBGP. If this is not supported by your IOS revision, you can use "maximum-paths" (which works for EBGP) and set as_number to a private value such as 64512.+ Avoiding Fragmentation+ +Fragmentation of encapsulated return packets to the LAC may be avoided +for TCP sessions by adding a firewall rule to clamps the MSS on +outgoing SYN packets. + +The following is appropriate for interfaces with a typical MTU of +1500: + ++iptables -A FORWARD -i tun+ -o eth0 \ + -p tcp --tcp-flags SYN,RST SYN \ + -m tcpmss --mss 1413:1600 \ + -j TCPMSS --set-mss 1412 ++ PerformancePerformance is great.
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