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--- network_stuff:linux [2023/01/17 09:56] – jotasandoku
+++ network_stuff:linux [2024/10/06 17:17] (current) – jotasandoku
@@ Line 121: / Line 121: @@
   * DHCPRequest: src:0.0.0.0 ; dst: broadcast << PACKET HAS BOOTP FLAG UNSET
   * DHCPAck: : src: server IP ; dst: client-mac + tentative IP Address
+===== DHCP Options =====
+  * **Default gateway (3):** Specifies the default gateway. Not used in DHCPv6.
+  * **Domain names (15):** Provides domain names for DNS resolution.
+  * **Vendor-Specific Info (43):** Used in Cisco PnP to point to the PnP server.
+  * **Subnet Mask (1):** Defines the subnet mask for the network.
+  * **IP lease time (51):** Specifies the duration of the IP address lease.
+  * **Renewal time (58):** Time when the client should renew the lease with the DHCP server.
+  * **Rebinding time (59):** Time when the client should attempt to rebind if the lease cannot be renewed.
+  * **Bootfile name (67):** Location of the boot file or script, often used in ZTP (Zero Touch Provisioning).
+  * **Relay Agent Info (82):** Adds metadata (e.g., VLAN, switch ID) to DHCP requests. Enabled by default with DHCP snooping for security. Can cause issues with non-Cisco DHCP servers.
+    * **Suboptions:**
+      * **Circuit ID:** Identifies the switch port (e.g., VLAN 10, port 2).
+      * **Remote ID:** Identifies the relay agent (e.g., Switch-1).
+===== Additional Relevant Options =====
+  * **DNS Servers (6):** Provides the IP addresses of DNS servers.
+  * **Router (3):** Specifies the router’s IP address for client devices.
+  * **TFTP Server (66):** Location of the TFTP server, often used for network device configurations.
+  * **NTP Servers (42):** Specifies the Network Time Protocol (NTP) server to synchronize time.
@@ Line 292: / Line 313: @@
   iptables-restore /etc/sysconfig/iptables
 Classical view:
-  iptables -L -v
+  iptables -L -v  # -t <nat/filter/mangle>
 Save and apply (debian):
   iptables-save
@@ Line 348: / Line 369: @@
 ----
 BRCTL COMMANDS
+[[https://www.thegeekstuff.com/2017/06/brctl-bridge/]]
   brctl show
   brctl addbr br0
@@ Line 353: / Line 375: @@
 To disable the network bridge, just shut down the interface:
    ip link set <name-of-the-bridge> down
+To delete a bridge link:
+   ip link set <name-of-the-bridge> down
+   # usefule when getting the error Network is already in use by interface
 \\
@@ Line 434: / Line 459: @@
   telnet google.com 443 > test_myhost2 < escape
+GENERATE TRAFFIC:
 ----
@@ Line 456: / Line 483: @@
   dig +noall +answer google.de
   dig +trace rule11.tech
-  dig -x 209.132.183.81 +short    # reverse records
+  dig -x 142.250.187.238 @9.9.9.9 +short   # PTR (reverse DNS record)
+  dig NS panda314159.net @9.9.9.9 +short   # DNS name server
+  dig SOA panda314159.net @9.9.9.9 +short  # Authoritative server (Start Of Authority)
   dig @9.9.9.9 redhat.com  # for a specific dns server
   dig yahoo.com +short
@@ Line 480: / Line 509: @@
 List all PCI devices
   lspci
+  * BDF or B/D/F, as abbreviated from bus/device/function
+    * Bus number: pci specification allows up to 256 buses. The bus number is the address for the device in the PCI world.
+    * Device number: It can be 32 devicesi in each bus
+    * Function number
+      * Capabilities
+[[https://en.wikipedia.org/wiki/PCI_configuration_space]]
 List USB devices
   lsusb
@@ Line 491: / Line 529: @@
 ----
+__**CONSOLE ACCESS SCENARIOS**__
+\\
+**IPMI**
+  * IPMI: is a set of computer interface specifications for an autonomous computer subsystem that provides management and monitoring capabilities independently of the host system's CPU, firmware (BIOS or UEFI) and operating system.
+    * IPMI is: Netscaler LOM, Dell iDRAC, HP iLO, IBM IMM ..
+ipmitool : [[https://github.com/ipmitool/ipmitool]] simple command-line interface to this baseboard management controller (BMC). It follows the IPMI specification. Normally ipmi is over lan, not serial. BMC encapsulated in Remote Management Control
+Protocol (RMCP)
+  ipmitool mc selftest    # testing ipmi
+  ipmitool -vv mc info
+  ipmitool sel list    # sel is System Event Log
+  base /tmp/ipmiutil sensor
+\\
 \\
@@ Line 850: / Line 903: @@
 DELL R740 RISERS AND PCI CONFIGURATION:
 \\
-{{ :network_stuff:dell_risers_configuration.docx |}}
+{{ :network_stuff:dell-r740_risers_configuration.docx |}}
@@ Line 1031: / Line 1084: @@
 ----
+JIRA
+\\
+----
@@ Line 1083: / Line 1141: @@
 TC NOTES TRAFFIC CONTROL:\\
   - [[http://luxik.cdi.cz/~devik/qos/htb/manual/userg.htm]] (in 7. Understanding statistics)
-  - This is a nice (and modern) tc frontend for linux (unrelated to the ISP): [[https://github.com/tylertreat/Comcast]]
+  - This is a nice (and modern) tc frontend for linux in python: [[https://github.com/thombashi/tcconfig]]
 ----
 FQ NOTES

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