Autosave: 2025-01-13 20:54:49

neuron/4769804b-fe54-4891-992f-720e46f2fc37/Monitor_DNS_resolution_and_internet_connectivity_script.md

@@ -1,18 +0,0 @@
----
-tags: [procedural, networks]
-created: Saturday, January 04, 2025
----
-
-# Monitor DNS resolution and internet connectivity script
-
-```bash
- while true; do
-    date
-    echo "DNS check:"
-    host google.com
-    echo "Ping check:"
-    ping -c 1 google.com | grep "time="
-    echo "---"
-    sleep 5
-done
-```

neuron/cd5cdd66-905b-4f1f-b8e8-3a11ad507325/ICMP_Protocol.md

@@ -0,0 +1,17 @@
+---
+tags: [networks]
+created: Monday, January 13, 2025
+---
+
+# ICMP Protocol
+
+The Internet Control Message Protocol operates alongside the
+[Internet Protocol](Internet_Layer_of_Internet_Protocol.md) at the
+[Transport Layer](Transport_Layer_of_Internet_Protocol.md).
+
+It doesn't carry any actual user data and thus there is no
+[Application Layer](Application_Layer_of_Internet_Protocol.md) processes above
+it. It's usage is primarily for diagnostics and debugging. When network problems
+occur, ICMP generates messages to report errors back to the source.
+
+Probably the most familiar tools related to ICMP is [Ping](Ping.md).

neuron/cd5cdd66-905b-4f1f-b8e8-3a11ad507325/Monitor_DNS_resolution_and_internet_connectivity_script.md

@@ -0,0 +1,23 @@
+---
+tags: [networks, procedural]
+created: Monday, January 13, 2025
+---
+
+# Monitor DNS resolution and internet connectivity script
+
+```bash
+ while true; do
+    date
+    echo "DNS check:"
+    host google.com
+    echo "Ping check:"
+    ping -c 1 google.com | grep "time="
+    echo "---"
+    sleep 5
+done
+```
+
+See [ping](./Ping.md) for more details on what this is doing.
+
+The `host` command contacts a DNS server and does a reverse lookup for the
+IP-address of the human-readable domain name.

neuron/cd5cdd66-905b-4f1f-b8e8-3a11ad507325/Ping.md

@@ -0,0 +1,38 @@
+---
+tags: [networks, procedural]
+created: Monday, January 13, 2025
+---
+
+# Ping
+
+`ping` is perhaps the most basic network debugging tool. It sends
+[ICMP](./ICMP_Protocol.md) echo request packets to a recipient host.
+
+If the recipient receives the packet and is configured to reply, it sends an
+ICMP echo response packet in return.
+
+For example:
+
+```
+$ ping google.com
+PING google.com (142.250.200.14) 56(84) bytes of data.
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=1 ttl=116 time=19.1 ms
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=2 ttl=116 time=19.2 ms
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=3 ttl=116 time=19.1 ms
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=4 ttl=116 time=21.1 ms
+```
+
+The first indicates the IP address of the host you are pinging (once per second,
+by default). The subsequent lines are the response packets, echoed back from
+this host.
+
+The `icmp_seq` is the number of the request in the sequence. If there was to be
+a gap in the sequence, this would be the clearest indication of a connection
+problem.The packets should not arrive out of order since there is only one
+packet being sent per second.
+
+`time` is the round-trip time - from the sending of the packet to its return to
+the sender.
+
+If the packet cannot reach the destination host, the final router to see the
+packet retunes a "host unreachable" packet to `ping`.

neuron/cd5cdd66-905b-4f1f-b8e8-3a11ad507325/index.md

@@ -13,27 +13,27 @@ computer science.
 
 ![not-by-ai-badge](static/not-by-ai-alternative--light.svg)
  
-**Build ID:** 4769804b-fe54-4891-992f-720e46f2fc37
+**Build ID:** cd5cdd66-905b-4f1f-b8e8-3a11ad507325
 
-**Published:** Fri 10 Jan 2025 17:09:45
+**Published:** Mon 13 Jan 2025 20:54:48
 
 ### Recent edits 
 
+- [[Ping]] 
+- [[Monitor_DNS_resolution_and_internet_connectivity_script]] 
+- [[ICMP_Protocol]] 
 - [[IP_addresses]] 
 - [[View_IP_addresses]] 
 - [[747589ad_effects_of_privacy_violation]] 
 - [[fbbfbc32-political-accommodation-inveigelment-surveillance-capitalism]] 
 - [[f6564af9_AOL_and_early_internet_enclosure]] 
 - [[Weaving_the_Web_Berners_Lee]] 
-- [[Monitor_DNS_resolution_and_internet_connectivity_script]] 
 - [[738d0481_sound_recording_as_wave_phenomena]] 
 - [[Audio_file_formats]] 
 - [[Binary_encoding_of_sound]] 
-- [[Recording_and_playback_of_sound]] 
-- [[Type_hinting]] 
 
 
-### All notes (515) 
+### All notes (517) 
 
 - [[0716531c_rewilding_the_internet]] 
 - [[241fe1a3_the_Web_versus_modem_BBSs]] 
@@ -248,6 +248,7 @@ computer science.
 - [[Headless_Raspi_network_setup]] 
 - [[Heap_memory]] 
 - [[Hexadecimal_number_system]] 
+- [[ICMP_Protocol]] 
 - [[IP_addresses]] 
 - [[Identify_merged_branches]] 
 - [[Importing_MongoDB_data]] 
@@ -362,6 +363,7 @@ computer science.
 - [[Passing_arguments_and_options_to_Bash_scripts]] 
 - [[Passing_arguments_to_Python_scripts]] 
 - [[Peer_to_peer_network]] 
+- [[Ping]] 
 - [[Ports_in_NodeJS]] 
 - [[Practical_walkthrough_Lambda_creation_within_AWS]] 
 - [[Prefixes_for_units_of_electrical_measurement]] 

zk/ICMP_Protocol.md

@@ -0,0 +1,17 @@
+---
+tags: [networks]
+created: Monday, January 13, 2025
+---
+
+# ICMP Protocol
+
+The Internet Control Message Protocol operates alongside the
+[Internet Protocol](Internet_Layer_of_Internet_Protocol.md) at the
+[Transport Layer](Transport_Layer_of_Internet_Protocol.md).
+
+It doesn't carry any actual user data and thus there is no
+[Application Layer](Application_Layer_of_Internet_Protocol.md) processes above
+it. It's usage is primarily for diagnostics and debugging. When network problems
+occur, ICMP generates messages to report errors back to the source.
+
+Probably the most familiar tools related to ICMP is [Ping](Ping.md).

zk/Monitor_DNS_resolution_and_internet_connectivity_script.md

@@ -1,6 +1,6 @@
 ---
-tags: [procedural, networks]
-created: Saturday, January 04, 2025
+tags: [networks, procedural]
+created: Monday, January 13, 2025
 ---
 
 # Monitor DNS resolution and internet connectivity script
@@ -16,3 +16,8 @@ created: Saturday, January 04, 2025
     sleep 5
 done
 ```
+
+See [ping](./Ping.md) for more details on what this is doing.
+
+The `host` command contacts a DNS server and does a reverse lookup for the
+IP-address of the human-readable domain name.

zk/Ping.md

@@ -0,0 +1,38 @@
+---
+tags: [networks, procedural]
+created: Monday, January 13, 2025
+---
+
+# Ping
+
+`ping` is perhaps the most basic network debugging tool. It sends
+[ICMP](./ICMP_Protocol.md) echo request packets to a recipient host.
+
+If the recipient receives the packet and is configured to reply, it sends an
+ICMP echo response packet in return.
+
+For example:
+
+```
+$ ping google.com
+PING google.com (142.250.200.14) 56(84) bytes of data.
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=1 ttl=116 time=19.1 ms
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=2 ttl=116 time=19.2 ms
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=3 ttl=116 time=19.1 ms
+64 bytes from lhr48s29-in-f14.1e100.net (142.250.200.14): icmp_seq=4 ttl=116 time=21.1 ms
+```
+
+The first indicates the IP address of the host you are pinging (once per second,
+by default). The subsequent lines are the response packets, echoed back from
+this host.
+
+The `icmp_seq` is the number of the request in the sequence. If there was to be
+a gap in the sequence, this would be the clearest indication of a connection
+problem.The packets should not arrive out of order since there is only one
+packet being sent per second.
+
+`time` is the round-trip time - from the sending of the packet to its return to
+the sender.
+
+If the packet cannot reach the destination host, the final router to see the
+packet retunes a "host unreachable" packet to `ping`.