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--- blog:linux:connection_tracking_3_state_and_examples [2022-08-08] – added link to new flowtables article Andrej Stender
+++ blog:linux:connection_tracking_3_state_and_examples [2023-09-04] (current) – fix typo "UPD" -> "UDP" Andrej Stender
@@ Line 335: / Line 335: @@
 ICMP //echo-request// and //echo-reply// traversing ct hook functions,
 causing tracked connection to be created and later deleted,
-showing state and timeout changes as those occur.
+showing state and timeout changes as those occur (click to enlarge).
 </caption>
 </figure>
@@ Line 347: / Line 347: @@
 in its //tuples// to do that; see function ''[[https://elixir.bootlin.com/linux/v5.10.19/source/net/netfilter/nf_conntrack_proto_icmp.c#L27|icmp_pkt_to_tuple()]]''.
-===== UPD Example =====
+===== UDP Example =====
 This example demonstrates state changes of a tracked connection in case of a [[wp>Domain_Name_System|DNS]] //query// + //response//, as shown in Figure
 {{ref>ctudpexmsgs}}. The client host sends a DNS //query// message to
@@ Line 386: / Line 386: @@
 {{ :linux:nf-ct-udp-ex.png?direct&700 |}}
 <caption>
-DNS //query// and //response// via UDP packets, traversing ct hook functions, causing tracked connection to be created and later deleted, showing state and timeout changes as those occur.
+DNS //query// and //response// via UDP packets, traversing ct hook functions, causing tracked connection to be created and later deleted, showing state and timeout changes as those occur (click to enlarge).
 </caption>
 </figure>
@@ Line 501: / Line 501: @@
 {{ :linux:nf-ct-tcp-ex-hs.png?direct&700 |}}
 <caption>
-TCP 3-way handshake: packets traversing ct hook functions, causing tracked connection to be created, confirmed, established and assured.
+TCP 3-way handshake: packets traversing ct hook functions, causing tracked connection to be created, confirmed, established and assured (click to enlarge).
 </caption>
 </figure>
@@ Line 508: / Line 508: @@
 {{ :linux:nf-ct-tcp-ex-psh.png?direct&700 |}}
 <caption>
-TCP payload data transfer: packets traversing ct hook functions, adjusting timeout depending on outstanding TCP ACK from peer.
+TCP payload data transfer: packets traversing ct hook functions, adjusting timeout depending on outstanding TCP ACK from peer (click to enlarge).
 </caption>
 </figure>
@@ Line 515: / Line 515: @@
 {{ :linux:nf-ct-tcp-ex-fin.png?direct&700 |}}
 <caption>
-TCP connection termination((TCP connection termination consists of two independent 2-way handshakes, which can result in 4 packets being exchanged. However, if both sides like to terminate simultaneously, then this can also result in just 3 packets, as shown here. I chose that shorter variant in this example, to prevent this figure from getting too big. ;-) )): packets traversing ct hook functions, causing timeout to be adjusted, after final timeout expiration, tracked connection is deleted.
+TCP connection termination((TCP connection termination consists of two independent 2-way handshakes, which can result in 4 packets being exchanged. However, if both sides like to terminate simultaneously, then this can also result in just 3 packets, as shown here. I chose that shorter variant in this example, to prevent this figure from getting too big. ;-) )): packets traversing ct hook functions, causing timeout to be adjusted, after final timeout expiration, tracked connection is deleted (click to enlarge).
 </caption>
 </figure>
@@ Line 537: / Line 537: @@
   * [[https://conntrack-tools.netfilter.org/manual.html|The conntrack-tools user manual (Pablo Neira Ayuso, 2012)]]
-//published 2021-08-07//, //last modified 2022-08-08//
+//published 2021-08-07//, //last modified 2023-09-04//