[syslog-ng] Problems parsing Cisco syslogs

N. Max Pierson nmaxpierson at gmail.com
Mon Mar 4 23:56:03 UTC 2019 

I have found a couple of cases where NXOS and IOS messages do not contain
the mnemonic. And the tracebacks do not contain a timestamp at all. I
should also mention that I have keep_hostname and keep_timestamp set to off
however the traceback message doesn't contain a timestamp in either case.
There is also an instance where a specific log is wrapped into a new
message due to length I'm guessing and doesn't contain the mnemonic and the
actual message portion of the log starts with several spaces before the
text.

And NXOS doesn't seem to have a seq number after the <###> start of the
message.

Having all of this said, is there a way to write at the end of those if
statements that takes anything that isn't matched past the <###> and still
logs it so that it isn't dropped (or anything that doesn't match the
triplet)? If I understood all of the elements in the plugin.conf file I
would gladly write it myself but there are several things in that file that
I do not understand. Is there any documentation on the block statements and
logic that I can look at to help me out?

Regards,
Max

On Mon, Mar 4, 2019 at 2:00 PM Scheidler, Balázs <
balazs.scheidler at oneidentity.com> wrote:

> It was a bit strange that nxos starts with a colon and that a cisco
> message didn't have a mnemonic. Cisco messages by my experience always
> contain a triplet and this one isn't, and doesn't seem to have a timestamp
> either. If you say that this was recorded the way you mentioned then i
> believe you :), they just looked a bit odd.
>
> Do all messages from the same device look the same? Or these are just the
> exceptions?
>
> Also what is nxos?
>
> On Sat, Mar 2, 2019, 21:37 Scheidler, Balázs <
> balazs.scheidler at oneidentity.com wrote:
>
>> Can you please include the log sample as it was received by syslog-ng?
>> This seems to have been mangled already.
>>
>> On Fri, Mar 1, 2019, 23:16 N. Max Pierson <nmaxpierson at gmail.com wrote:
>>
>>> Here are 2 different samples of logs without the mnemonic, one is IOS
>>> and the other is NX-OS
>>>
>>> IOS, no-parse log to file
>>> --
>>> Mar  1 16:06:07 hostname1 <185>78919861: -Traceback= 151644C 151763C
>>> 17F0094 1B8BDE8 1B82858
>>>
>>>
>>> NX-OS, no-parse log to file
>>> --
>>> Mar  1 16:10:41 hostname1 <189>: 2019 Mar  1 16:10:41 CST: last message
>>> repeated 3 times
>>>
>>> Regards,
>>> Max
>>>
>>> On Thu, Feb 28, 2019 at 5:45 PM Scheidler, Balázs <
>>> balazs.scheidler at oneidentity.com> wrote:
>>>
>>>> Log samples would be appreciated.
>>>>
>>>> On Thu, Feb 28, 2019, 18:11 N. Max Pierson <nmaxpierson at gmail.com
>>>> wrote:
>>>>
>>>>> Balázs,
>>>>>
>>>>> I modified the plugin.conf XML file (https://pastebin.com/9BruYy0S -
>>>>> added lines 62-65) for the cisco-parser and I was able to capture NX-OS
>>>>> syslogs. I also noticed that the default parser is not matching syslogs
>>>>> that do not include the Cisco mnemonic (both for IOS and NX-OS). While I
>>>>> was able to fix the NX-OS issues (which was a date parsing problem), i'm
>>>>> not sure what needs to be changed/added in this file so that even logs that
>>>>> do not contain the mnemonic are matched. Can anyone shed some light on what
>>>>> part of this parser needs to be changed to resolve the issue? I can post
>>>>> some examples of a log that doesn't contain the mnemonic should you need
>>>>> them.
>>>>>
>>>>> Regards,
>>>>> Max
>>>>>
>>>>> On Tue, Feb 26, 2019 at 11:14 AM Scheidler, Balázs <
>>>>> balazs.scheidler at oneidentity.com> wrote:
>>>>>
>>>>>> The cisco-parser() should take care about messages from cisco routers
>>>>>> assuming they were received using flags(no-parse). It will automatically
>>>>>> detect timestamp formats, but its not perfect, so if you encounter
>>>>>> something that it doesn't properly parse, do let us know, so we can add it.
>>>>>>
>>>>>> Also, default-network-drivers() makes it possible to receive both
>>>>>> cisco and non-cisco logs on the same port, automatically recognizing the
>>>>>> appropriate format. This driver relies on the app-parser() framework, which
>>>>>> can be extended by application specific parsers. With that you can
>>>>>> construct your specific source driver configuration if you find
>>>>>> default-network-drivers () too complicated.
>>>>>>
>>>>>> You can find all of these in the documentation, and their source in
>>>>>> the syslog-ng configuration library (scl for short, usually in
>>>>>> /usr/share/syslog-ng/include/scl).
>>>>>>
>>>>>> On Tue, Feb 26, 2019, 18:08 Sandor Geller <sandor.geller at ericsson.com
>>>>>> wrote:
>>>>>>
>>>>>>> Hello,
>>>>>>>
>>>>>>> When the no-parse flag is used then the macros referencing various
>>>>>>> parts of the message aren't filled in. HOST could get looked up using a
>>>>>>> reverse DNS lookup unless the keep_hostname option is set. The syslog
>>>>>>> priority is set to user.notice when parsing is disabled.
>>>>>>>
>>>>>>> Did you take a look at the existing cisco parser? Using it or
>>>>>>> adopting it should ease your job. If you could configure the Ciscos to use
>>>>>>> other port than anything else (which speaks syslog, Cisco devices usually
>>>>>>> aren't such...) would be even better.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Sandor
>>>>>>>
>>>>>>> On 02/26/2019 05:36 PM, N. Max Pierson wrote:
>>>>>>>
>>>>>>> Hi List,
>>>>>>>
>>>>>>> I have been trying to get something in place that can parse syslogs
>>>>>>> from various Cisco devices. The message format is almost the same with a
>>>>>>> few exceptions. Here is what I have tried and it works but now it has
>>>>>>> created another problem I do not know how to troubleshoot.
>>>>>>>
>>>>>>> So that I could see exactly what was being parsed, I disabled the
>>>>>>> default parsing using the below.
>>>>>>>
>>>>>>> source s_network { udp(ip(0.0.0.0) port(514) flags(no-parse)); };
>>>>>>>
>>>>>>> rewrite r_cisco{
>>>>>>> subst('^<\d+>(\d+:|:)\s+(\.\w+|\w+)\s+\d+\s+\d+\s\d+:\d+:\d+:\s|^<\d+>:\s+\d+\s+\w+\s+\d+\s+\d+:\d+:\d+\s\w+:\s|^<\d+>(\d+:|:)\s',
>>>>>>> "", value("MESSAGE"), type("pcre"), flags("ignore-case")); };
>>>>>>>
>>>>>>> destination d_mysql {
>>>>>>>     sql(type(mysql)
>>>>>>>     host("127.0.0.1")
>>>>>>>     username("syslog-ng")
>>>>>>>     password("password")
>>>>>>>     database("syslog")
>>>>>>>     table("messages_${HOST}")
>>>>>>>     columns("datetime datetime", "host varchar(50)", "level
>>>>>>> varchar(10)", "message text")
>>>>>>>     values("${R_YEAR}-${R_MONTH}-${R_DAY}
>>>>>>> ${R_HOUR}:${R_MIN}:${R_SEC}", "${HOST}", "${LEVEL}", "${MESSAGE}")
>>>>>>>     indexes("datetime", "level")
>>>>>>>     );
>>>>>>> };
>>>>>>>
>>>>>>> log { source(s_network); rewrite(r_cisco); destination(d_mysql); };
>>>>>>>
>>>>>>> This works perfectly as it formats the message as I want and covers
>>>>>>> IOS and NX-OS devices. The problem is when I turned off the default parser,
>>>>>>> now all of my logs show "notice" in the $LEVEL macro and doesn't reflect
>>>>>>> the real message header level. The $HOST macro still works fine however.
>>>>>>>
>>>>>>> Is this the expected behavior that the message header fields are not
>>>>>>> parsed as well as the $MESSAGE itself not being parsed? How can map the
>>>>>>> header level field properly to the $LEVEL marco if I disable the default
>>>>>>> parser?
>>>>>>>
>>>>>>> Regards,
>>>>>>> Max
>>>>>>>
>>>>>>>
>>>>>>>
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>>>>>>>
>>>>>>>
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>>>>>>>
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>>>>>> http://www.balabit.com/support/documentation/?product=syslog-ng
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>>>>>>
>>>>>>
>>>>> ______________________________________________________________________________
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>>>>> http://www.balabit.com/support/documentation/?product=syslog-ng
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>>>>>
>>>>>
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>>>>
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