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syslog (1)

syslog (1). The purpose of syslog is to write system messages to a log Syslog messages can include everything from critical alarm conditions to ordinary debugging statement It provides a general trail of activities

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syslog (1)

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  1. syslog (1) • The purpose of syslog is to write system messages to a log • Syslog messages can include everything from critical alarm conditions to ordinary debugging statement • It provides a general trail of activities • It provides the capability for the device to emit event messages without solicitation

  2. syslog (2) • Syslog message has 2 parts • A message header and the message body • The message body contains the content of the message itself (english text, unstructured) • The message header contains minimal but essential information in structured manner

  3. General syslog message • 179.19.209.130 – IP Address • 000024 – sequence number • Apr 12 18:01:55:643 – local time • ENV_MON – facility emitting the alarm • 1 – severity • SHUTDOWN – Event

  4. syslog Protocol • IETF is in process of passing a particular version of syslog as a standard • RFC 3164 BSD syslog protocol • RFC 3195 reliable delivery for syslog • Refer to RFC3164 (RFC 5424) • UDP is used as transport service • Port 514

  5. definition • A machine that can generate a message will be called a "device". • A machine that can receive the message and forward it to another machine will be called a "relay". • A machine that receives the message and does not relay it to any other machines will be called a "collector". This has been commonly known as a "syslog server".

  6. syslog message • Consists of 3 parts :PRI /HEADER/MSG • Length Maximum 2048 bytes or less

  7. PRI (Priority) part • Priority – combination of a facility and severity • Facility – category of a message (kernel message) , it is a numeric code • Severity – numeric code 0 -7 , 0 is the most severe • Priority is formed by multiplying the numeric code of the facility by 8 and adding the severity • Facility 7 and severity 3 , so priority = 59

  8. Example of Facility code

  9. Example of Severity

  10. HEADER part (1) • The HEADER part contains a timestamp and an indication of the hostname or IP address of the device • The HEADER part of the syslog packet MUST contain visible (printing) characters (7-bit Ascii) • HOSTNAME field will contain the hostname or IP address • Timestamp field will contain the local time and is in the format of “Mmm dd hh:mm:ss"

  11. HEADER part (2) • Mmm –month of the year with the first character in uppercase and the other two characters in lowercase “Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec” • dd -dd is the day of the month. • If the day of the month is less than 10, then it MUST be represented as a space and then the number. • For example, • the 7th day of August would be represented as "Aug 7", with two spaces between the "g" and the "7

  12. HEADER part (3) • hh:mm:ss is the local time. • The hour (hh) is represented in a 24-hour format. • Valid entries are between 00 and 23 • The minute (mm) and second (ss) entries are between 00 - 59

  13. MSG part(1) • It contains some additional information of the process that generated the message, and then the text of the message • It has 2 fields : TAG and CONTENT • TAG field will be the name of the program or process that generated the message.(not exceed 32 chars) • CONTENTfield contains the details of the message. • This has traditionally been a freeform message that gives some detailed information of the event

  14. Example of syslog message • <34> Oct 11 22:14:15 mymachine su: ’su root’ failed for lonvick on /dev/pts/8 • <34> - priority • Oct 11 22:14:15 – timestamp • mymachine – hostname • su – TAG • : ’su root’ failed for lonvick on /dev/pts/8- Content

  15. Security consideration (1) • Authentication • The syslog delivery mechanism does not strongly associate the message with the message sender • a misconfigured machine may send syslog messages to a collector representing itself as another machine • An attacker may transmit syslog messages to a collector.

  16. Security consideration (2) • Sequenced delivery • the syslog process and protocol do not ensure ordered delivery. • Reliable delivery • no mechanism within either the syslog process or the protocol to ensure delivery • May be maliciously intercepted or discarded • Message Integrity • syslog messages may be damaged in transit or an attacker may maliciously modify them.

  17. Security consideration (3) • Message observation • No mechanisms to provide confidentiality of the messages in transit. (clear-text messages) • Message Prioritization & Differentiation • No mechanism relating to priority message • Critical message and non critical message can be treated as equal in term of reception

  18. Security consideration (4) • Misconfiguration • The syslog message may go to untended receiver • Load Considerations • An attacker may perform a Denial of Service attack by filling the disk of the collector with false messages.

  19. syslog deployment (1) • Two roles are distinguished • syslog sender (management agent) • syslog receiver (management manager) • Syslog receiver (1) • Device itself writing the messages to a local log file • use circular log file for a limit size • Log files are created with a certain capacity

  20. syslog deployment (2) Circular log file

  21. syslog deployment (3) • syslog receiver (con’t) • Centralized logging host • Receiving messages from several devices and logging those messages • Applications access this logging host instead of individual devices • It often function as a syslog relay , forwarding syslog messages to various apps.

  22. syslog deployment (4) Logging host syslog relay

  23. Netconf (1) • Netconf is a network management protocol developed in the IETF by the Netconf working group. • It was published as RFC 4741. • The NETCONF protocol provides mechanisms to install, manipulate, and delete the configuration of network devices. • It also can perform some monitoring functions.

  24. Netconf (2) • It uses an Extensible Markup Language (XML) based data encoding for the configuration data as well as the protocol messages. • The NETCONF protocol operations are realized on top of a simple Remote Procedure Call (RPC) layer.

  25. Netconf Datastore (1) • The configuration information of devices can be thought of and handle as being contained in a datastore (like a file) • The datastore resembles a MIB. • Netconf provides the operations to manage those datastores. • SNMP targets the individual managed object in side MIB • Netconf targets the MIB as a whole or portion

  26. Netconf Datastore (2) A hierarchical datastore in Netconf

  27. Netconf Datastore (3) • Management operations can be applied to individual subtrees • This capability feature is called as subtree filtering

  28. Netconf and XML (1) • Netconf uses XML as encoding for its management operations • XML documents contain so-called tags to delimit different pieces of information • Tags are defined by users such as <email>alex@cisco.com(/email)

  29. Netconf Architecture (1)

  30. Netconf Architecture (2) • Transport layer (using Netconf over) • Secure Shell (SSH) RFC4742 • Block Extensible Exchange Protocol (BEEP) RFC4744 • Simple Object Access Protocol (SOAP) RFC4743 • Remote Procedure Call layer • Allow manager to invoke function on agent • rpc request / rpc reply

  31. Netconf Architecture (3) • The operation layer • To manipulate configuration files • Get-config / Edit-config • The content layer • Configuration data • The management information will be transported and exchanged as XML documents

  32. Netconf Message Structure • Fig 8-14

  33. A netconf request(1) • Ex 8-4

  34. A netconf request(2) • RPC tag <rpc message-id =“101 … > …. </rpc> - frame the overall message • Netconf operation – get-config <get-config> … </get-config> • <source>… </source> specifies the config being requested (running config) • <filter> … </filter> specifies the subtree within the config (all belongs in bgp)

  35. A netconf reply • Ex 8-5

  36. Management operations • Get-config – to retrieve config file (default is running config) • Get – to retrieve state information • Edit-config – to modify or change a configuration • Copy-config – to copy new configuration • Delete-config – to remove a configuration • Lock and unlock – to protect configuration file

  37. Netflow protocol/IPFIX(1) • RFC 3954 (Netflow V.9) • RFC 5101 (IPFIX- aka. Netflow V.10) • Netflow was introduced by cisco to collect data about networking traffic from a device. • Who are the top “talker” in the network • How much traffic is being exchanged between two destination • How are links in the network being used • Where are the traffic bottlenecks in the network?

  38. Netflow protocol/IPFIX(2) • Netflow communicates statistical information about IP-based data traffic that flow over router • The statistics are provided on a per-flow basis • A flow consists of all traffic that belongs to the same communication context • A file–transfer application ,all packets belong to the same transfer

  39. Fig 8-15

  40. Flow • Identified by the following information • Source address/Source port • Destination address/Destination port • Protocol type (TCP or UDP) • Type of service (TOS) • Input logical interface (same index in SNMP MIB) • Flow record includes the keys that identify the flow as well as the time when flow started /stopped /how many packets were transported

  41. Benefit • Allow network managers to account for detailed network use by individual users • Charge based on actual traffic consumption • Provide a wealth of data for traffic analysis, bottleneck and network planning • Provide tool to spot and defend against attacks on a network

  42. Netflow Protocol • Netflow version5 is commonly used • The newest version is RFC 3954 (version 9) • Flow informationis exported from the router in User Datagram Protocol (UDP) or Stream Control Transmission Protocol (SCTP) packets and collected using a netflow collector. • Juniper Networks provides a similar feature for its routers called Jflow . • Huawei Technology routers also support the same technology, but call it NetStream

  43. Netflow packet structure

  44. Packet structure • Header • Sequence number of the packet • The number of flow records contained in the Netflow packet • The version number of the netflow protocol itself • Flow record • keys to identify flow • Start/finish time • Statistical data

  45. Finishing the flow • No traffic has been detected on a flow for a certain time • A packet is detected at the app-protocol level that the data transfer supported by the flow has completed • If a flow has been going on for a long time (30 minutes) ,the router simply declare the flow ends and start a new one

  46. Management protocol positioning

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