Error Messages: “%CRYPTO-**_SPI”

Posted on May 17, 2024

In the realm of network management, encountering error messages is not uncommon. One such error that may pop up occasionally, even in an otherwise smoothly functioning VPN setup, is the “%CRYPTO-4-RECVD_PKT_INV_SPI” error. While it may seem alarming at first glance, understanding its cause and knowing how to address it can help maintain the integrity of your network connections.

What Causes “%CRYPTO-4-RECVD_PKT_INV_SPI” Errors? The “%CRYPTO-4-RECVD_PKT_INV_SPI: decaps: rec’d IPSEC packet has invalid spi” error message indicates that one side of an IPSEC tunnel has received a packet with an invalid Security Parameter Index (SPI). The SPI is crucial as it identifies the Security Association (SA) associated with the packet, containing vital information for handling encrypted traffic.

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BGP Regular Expressions

Posted on May 17, 2024

There can be instances where identifying all the networks from a certain provider may be too complicated or numerous, and a regular expression may be more suitable to filter all networks from a certain AS. Regular expression can be used for this.

A quick guide to regular expression

ModifierPurpose
_Matches a space
^Indicates the start of a string
$Indicates the end of a string
[]Matches a single character with a range of characters
–Indicates a range of numbers in brackets
[^]Excludes the characters listed in the brackets
()Nesting of search patterns uses parentheses
|Acts as an OR logic to a query
.Matches a single character including space
*Matches zero or more characters, or pattern
+Matches one or more instances of the character, or pattern
?Matches one or no instances of the character, or pattern
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Navigating OSPF Path Selection

Posted on May 16, 2024

A Deep Dive into Inter-area and Intra-area Routes, External Routes, and Link Costs

Introduction: Open Shortest Path First (OSPF) is a robust and widely used routing protocol in computer networks, particularly in large-scale enterprise environments. One of the key aspects of OSPF is its path selection mechanism, which determines how routers choose the best path to reach a destination. In this blog post, we’ll delve into OSPF path selection, focusing on inter-area and intra-area routes, type 1 and type 2 external routes, and the significance of link costs in the routing decision process.

Understanding OSPF Routing Hierarchy: OSPF organizes routers and networks into areas to scale efficiently. Routers within the same area share a common link-state database, which contains information about the network topology. OSPF defines two types of areas: backbone area (Area 0) and non-backbone areas (other numbered areas). Inter-area and intra-area routes are determined based on the area boundaries.

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Activate Office 365 via CMD

Posted on September 20, 2022

Microsoft Office 365 is software that provides all the tools for writing, counting, making databases, and also making presentations. This software is very popular because it is very widely used by many people in the world. By using this software the daily work related to optimization will be able to be made quickly and efficiently.

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