[ZBX-17661] net.dns.record output not consistent Created: 2020 Apr 30  Updated: 2024 Jul 29

Status: Confirmed
Project: ZABBIX BUGS AND ISSUES
Component/s: None
Affects Version/s: 4.4.8
Fix Version/s: None

Type: Problem report Priority: Trivial
Reporter: Dirk Jan de Vries Assignee: Aleksandre Sebiskveradze
Resolution: Unresolved Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: PNG File Schermafbeelding 2020-04-30 om 12.37.48.png    

 Description   

Steps to reproduce:

  1. zabbix_agentd -t net.dns.record[8.8.8.8,bentacera.nl,TXT] | grep v=spf1

 

 

The result of this command varies;

The SPF record most of the times ends with ... -all", but ... -al", ... al?", ...al&" are also output examples that should not be there. Also discussed on IRC, confirmed by other users. Tested it and confirmed on multiple zabbix agents.

Different output examples in attachment.

 Comments   
Comment by Andrejs Sitals (Inactive) [ 2020 May 01 ]

When this was discussed in IRC, zabbix_agentd -t was used. Output was grepped, grep v=spf1 was added to the command line. That =all string is at the end of the longest line. I tried it without grepping and saw that the last char is sometimes removed from other lines as well, e.g., last digit in "MS=..." rows sometimes was missing. Tested with the latest Zabbix 5 from master branch.

$ ./zabbix_agentd -t 'net.dns.record[8.8.8.8,bentacera.nl,TXT]'
net.dns.record[8.8.8.8,bentacera.nl,TXT]      [t|bentacera.nl         TXT      "MS=ms37830344"
bentacera.nl         TXT      "MS=ms47496172"
bentacera.nl         TXT      "MS=ms58429250"
bentacera.nl         TXT      "rbHCQvkUlj5d7Mowka5mKzJoD7UPY4NYqPtWX13BvQwBWzR5C2XZ/oCLcy055ZuuObvI5JNQzRez/aeJIG9eng=="
bentacera.nl         TXT      "v=spf1 mx:mailer.twinfield.com ip4:147.253.208.0/20 ip4:31.149.122.196/32 include:spf.by-tres.nl include:_spf.afasonline.nl include:_spf.payt.nl include:spf.protection.outlook.com include:spf.exclaimer.net include:_spf.zivver.com -al"
bentacera.nl         TXT      "zpy8Z+63zhNt/N+S6CWZpexjCwkefEPI0Ol9CO2tRCI="]

$ ./zabbix_agentd -t 'net.dns.record[8.8.8.8,bentacera.nl,TXT]'
net.dns.record[8.8.8.8,bentacera.nl,TXT]      [t|bentacera.nl         TXT      "MS=ms37830344"
bentacera.nl         TXT      "MS=ms4749617"
bentacera.nl         TXT      "MS=ms58429250"
bentacera.nl         TXT      "rbHCQvkUlj5d7Mowka5mKzJoD7UPY4NYqPtWX13BvQwBWzR5C2XZ/oCLcy055ZuuObvI5JNQzRez/aeJIG9eng=="
bentacera.nl         TXT      "v=spf1 mx:mailer.twinfield.com ip4:147.253.208.0/20 ip4:31.149.122.196/32 include:spf.by-tres.nl include:_spf.afasonline.nl include:_spf.payt.nl include:spf.protection.outlook.com include:spf.exclaimer.net include:_spf.zivver.com -all"
bentacera.nl         TXT      "zpy8Z+63zhNt/N+S6CWZpexjCwkefEPI0Ol9CO2tRCI="]

$ ./zabbix_agentd -t 'net.dns.record[8.8.8.8,bentacera.nl,TXT]'
net.dns.record[8.8.8.8,bentacera.nl,TXT]      [t|bentacera.nl         TXT      "MS=ms37830344"
bentacera.nl         TXT      "MS=ms47496172"
bentacera.nl         TXT      "MS=ms58429250"
bentacera.nl         TXT      "rbHCQvkUlj5d7Mowka5mKzJoD7UPY4NYqPtWX13BvQwBWzR5C2XZ/oCLcy055ZuuObvI5JNQzRez/aeJIG9eng=="
bentacera.nl         TXT      "v=spf1 mx:mailer.twinfield.com ip4:147.253.208.0/20 ip4:31.149.122.196/32 include:spf.by-tres.nl include:_spf.afasonline.nl include:_spf.payt.nl include:spf.protection.outlook.com include:spf.exclaimer.net include:_spf.zivver.com -all"
bentacera.nl         TXT      "zpy8Z+63zhNt/N+S6CWZpexjCwkefEPI0Ol9CO2tRCI"]

Output of Valgrind:

$ valgrind --leak-check=full ./zabbix_agentd -t 'net.dns.record[8.8.8.8,bentacera.nl,TXT]'
==78520== Memcheck, a memory error detector
==78520== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==78520== Using Valgrind-3.15.0 and LibVEX; rerun with -h for copyright info
==78520== Command: ./zabbix_agentd -t net.dns.record[8.8.8.8,bentacera.nl,TXT]
==78520== 
net.dns.record[8.8.8.8,bentacera.nl,TXT]      [t|bentacera.nl         TXT      "MS=ms37830344"
bentacera.nl         TXT      "MS=ms4749617"
bentacera.nl         TXT      "MS=ms58429250"
bentacera.nl         TXT      "rbHCQvkUlj5d7Mowka5mKzJoD7UPY4NYqPtWX13BvQwBWzR5C2XZ/oCLcy055ZuuObvI5JNQzRez/aeJIG9eng=="
bentacera.nl         TXT      "v=spf1 mx:mailer.twinfield.com ip4:147.253.208.0/20 ip4:31.149.122.196/32 include:spf.by-tres.nl include:_spf.afasonline.nl include:_spf.payt.nl include:spf.protection.outlook.com include:spf.exclaimer.net include:_spf.zivver.com -all"
bentacera.nl         TXT      "zpy8Z+63zhNt/N+S6CWZpexjCwkefEPI0Ol9CO2tRCI="]
==78520== 
==78520== HEAP SUMMARY:
==78520==     in use at exit: 4,550 bytes in 80 blocks
==78520==   total heap usage: 1,627 allocs, 1,547 frees, 222,217 bytes allocated
==78520== 
==78520== LEAK SUMMARY:
==78520==    definitely lost: 0 bytes in 0 blocks
==78520==    indirectly lost: 0 bytes in 0 blocks
==78520==      possibly lost: 0 bytes in 0 blocks
==78520==    still reachable: 4,550 bytes in 80 blocks
==78520==         suppressed: 0 bytes in 0 blocks
==78520== Reachable blocks (those to which a pointer was found) are not shown.
==78520== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==78520== 
==78520== For lists of detected and suppressed errors, rerun with: -s
==78520== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Comment by alex dekker [ 2024 Jul 29 ]

Still present in 7.0.1.

Try querying google.com TXT records, you will get all kinds of random output from Zabbix agent, in amongst "record overflow" and "cannot expand domain name" errors.

Comment by alex dekker [ 2024 Jul 29 ]

Agent2 handles this a lot better BUT you must use TCP mode for TXT queries, and the results are returned in random order.

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