Differences

This shows you the differences between two versions of the page.

--- advanced-firewall [2022/01/21 01:34] – -clarity, spelling, formatting hogwild
+++ advanced-firewall [2023/05/28 05:39] (current) – [Multicast] -condense, list/explain additional features of new IGMPv2 messages hogwild
@@ Line 1: / Line 1: @@
+====== Firewall ======
+The Firewall page allows you to configure options to protect or facilitate various types of network communications.
 ===== Firewall =====
-The Firewall page allows you to configure options to protect/facilitate certain network communications.\\
+{{:pasted:20220118-182859.png}} \\
-{{:pasted:20220118-182859.png}}\\  \\
+ \\ **WAN interfaces respond to ping and traceroute:  **If enabled, this allows your device to reply to ICMP ping and traceroute request packets from Internet hosts. This is necessary for //ping //and //traceroute to //work from the Internet.
-**WAN interfaces respond to ping and traceroute** - When enabled, this allows your device to respond to certain ICMP/UDP packets so that //ping //and //traceroute //from Internet hosts will work.
+**Limit communication to:  **This specifies the maximum number of requests per second to which the Firewall will reply. Setting a limit number is recommended to prevent DDoS attacks.\\   \\   \\ {{:pasted:20220118-183317.png}}\\
-**Limit communication to**: Specifies the maximum number of requests per second to which the Firewall will reply. Setting a limit number is recommended to prevent DDoS attacks.\\
+ \\
+**Enable TCP SYN cookies:  **Enabling this uses the "SYN cookies" technique to protect the router from SYN Flood attacks. This function encodes information from the SYN packet into the (SYN/ACK) response. This is a standard method for preventing SYN floods. However, it has certain limitations which may cause issues with some old TCP/IP stacks.
+**Enable DCSP Fix:  **Checking this enables a workaround for packet marking, a well-known issue related to DSCP when connected to Comcast.
+**Allow DHCP Spoofing: **
+**Smart MTU black hole detection:**
+===== NAT =====
+**NAT loopback:** This technique allows LAN devices to access each other via the router's WAN interface. Also known as "Hairpinning", this is commonly used when connecting to the DDNS domain of your router from the LAN. These days, this legacy setting is almost never needed. It also can create speed bottlenecks.
+  * All
+  * Forwarded Only
+  * Disabled
+\\
+{{::advanced-firewall-nat.jpg?454}} \\ \\
+**NAT target** - This defines the way NAT is implemented for use during loopback. Masquerade is the default, but involves an additional lookup. ad the mapping of done towards an interface. SNAT is minutely faster, as the NAT mapping points directly to the destination IP and so it bypasses the lookup stage. However, SNAT is less reliable than Masquerade.
  \\
-{{:pasted:20220118-183317.png}}\\  \\
-**Enable TCP SYN cookies** - Enabling this protects the router from SYN Flood attacks via a well-known technique called "SYN cookies". This technique encodes info from the SYN packet into the response (SYN/ACK). Despite being a standard technique, enabling this will create some secondary limitations that my not be well-handled by some old TCP/IP stacks.
+===== Multicast =====
+ \\ \\ {{:pasted:20220118-185509.png}}\\  \\
+**Enable IGMP proxy** - Checking this enables the IGMP (Internet Group Management Protocol) service.
+LAN0 - LAN3 Specifies which bridges will participate in IGMP, with the router acting as a proxy between selected LANs. This allows IGMP to work between VLANs.
+  * LAN0 - Checking this means the LAN0 bridge will participate in IGMP proxy.
+  * LAN1 - Checking this means the LAN1 bridge will participate in IGMP proxy.
+  * LAN2 - Checking this means the LAN2 bridge will participate in IGMP proxy.
+  * LAN3 - Checking this means the LAN3 bridge will participate in IGMP proxy.
+ \\
+**Enable quick leave** - This is a feature of IGMP v2 and later. Enabling this allows the router to stop streaming multicast to an IP address as soon as that device sends a "quick leave" IGMP packet.
+**Custom Configuration** - This option allows you to set advanced parameters for the IGMP proxy daemon. Consult official IGMP documentation before using this.\\   \\
+ \\ {{:pasted:20220118-190050.png}}\\  \\
+**Enable Udpxy** - Like IGMP proxy, Udpxy allows multicast communications between devices on different VLANs. Since their behavior is very similar, you are advised to use either Udpxy or IGMP proxy, but not both at once.
+**Upstream interface** - Here, enter the stream source is expected to live. (Default: blank).
+**LAN0/LAN1/LAN2/LAN3** - This specifies the location the streaming clients are expected to be found.
+**Enable client statistics** - Enabling this causes FreshTomato to collect statistics about Udpxy clients.
+**Max clients - ** This represents the maximum number of simultaneous Udpxy clients. Udpxy is is a lightweight protocol, and only works well for a limited number of clients. For this reason, you might want to impose a maximum limit.
+**Udpxy port**- This specifies the port on which you can recive Udpxy information from your router.\\  \\   \\  {{:pasted:20220118-190844.png}}\\  \\
-**Enable DCSP Fix** - This enables a workaround for a well-known issue related to DSCP (packet marking) when connected to the Comcast ISP.
+**Efficient Multicast Forwarding (IGMP Snooping) -** IGMP snooping makes the router's switch facilitate discovery of Multicast IGMP clients. This will help to send multicast traffic only towards ports with at least one multicast subscriber, reducing overall multicast traffic.
-**IPv6 IPSec Passthrough** - FIXME\\
+However, caution is advised. IGMP Snooping can interfere with proper functioning of UPnP or DLNA. This can make Multicast configuration errors or deficiencies appear as UPnP issues. Enabling IGMP snooping on a router's/switch will interfere with UPnP/DLNA device discovery.  Specifically, it can interfere with SSDP protocol transmissions. If IGMP snooping is incorrectly or incompletely configured (say, without an active querier or IGMP proxy), this make UPnP appear unreliable.
-{{:pasted:20220118-184523.png}}\\
+A common symptom of this is a network host (say, a Smart TV) which appears after it's powered on, but then "disappears" from the network after a few minutes. To be more precise, often this period is 30 minutes. This is because the default setting for when IGMP group membership will expire. Please be aware of the wireless multicast forwarding setting in the the //Advanced///[[advanced-wireless|Wireless]] menu.
-**NAT loopback** - also known as "Hairpinning", this well-known technique allows LAN devices to access another LAN device via the WAN interface of your router. This is common practice, such as when calling the DDNS domain of your router from the LAN for administration purpose. This is a legacy setting and is rarely, if ever needed currently. Also, this function can create a bottleneck on fast connections.
+**Force IGMPv2** - IGMPv2 enhances IGMP with additional messages/behavior to optimize end-to-end client-server communication. Perhaps the most important of these additional messages is the "Leave Group" message. When a host no longer wants to listen to a multicast group address, it will report to the router that it has stopped listening. In v1, the host simply stopped listening, without informing the router.
-**NAT target** - Defines the way NAT is implemented for the sake of Hairpinning. Masquerade is the default however this involves an additional lookup ad the mapping of done towards an interface. SNAT is faster (if ever measurable) as the NAT mapping point directly to the destination IP hence bypassing the lookup stage.
+Other features of IGMPv2 include:
-Multicast\\  {{:pasted:20220118-185509.png}}\\  **Enable IGMP proxy** - Runs the IGMP (Internet Group Management Protocol) for your router.\\  **LAN0/LAN1/LAN2/LAN3** - where enabled the bridges will partecipate in IGMP subscription using the router as a proxy between the LANs selected. This essentially allows IGMP to work between VLANs.\\  **Enable quick leave** - This is a feature of IGMP v2 and allows the router to stop streaming of the multicast IP as soon as the end device sends the quick leave IGMP packet.\\  **Custom Configuration** - This option allows you to set up some advanced parameters for the IGMP proxy daemon. Make sure to consult the official documentation.\\
+Group specific membership query. The router can now send a membership query for a specific group address. When the router receives a leave group message, it will use this query to check if there are still any hosts interested in receiving the multicast traffic.
-{{:pasted:20220118-190050.png}}\\  **Enable Udpxy** - Similarly to IGMP proxy Udpxy allows multicast communication between sender and receiver sitting in different VLANs. NOTE: since the behavior is pretty much identical you should use either but not both at the same time.\\  **Upstream interface** - leave empty for default - Defines where the stream source is expected to live.\\  **LAN0/LAN1/LAN2/LAN3** - this is where the stream clients are expected to live.\\  **Enable client statistics** - As the option suggest if enabled statistical information about the clients is collected.\\  **Max clients** - Considering this is a lightwave protocol it works well for a limited number of clients, you might want to impose a maximum number if any.\\  **Udpxy port**- This is where you can consult the Udpxy information on your router.\\
+MRT (Maximum Response Time) field. This new field in query messages specifies how much time hosts have to respond to the query.
-{{:pasted:20220118-190844.png}}\\  **Efficient Multicast Forwarding (IGMP Snooping)** - IGMP snooping is a way to have the switch (router) facilitating the discovery of multicast (IGMP) clients. Beware that enabling IGMP snooping might interfare with some multicast based applications/protocols, a well know issue revolve around Upnp.\\  **Force IGMPv2** - IGMPv2 enhances the IGMP communication supporting additional messages/behavior to optimise the end-to-end communication between client and server. Possibly the most important being the "Group Leave" message which is lacking instead in IGMP v1.\\
+Querier election process. When two routers are connected to the same subnet, only one of them should send query messages. Having an "election" process ensures only one router, the router with the lowest IP address, becomes the active querier.\\   \\

FreshTomato Wiki

User Tools

Site Tools

Differences

Page Tools