Problem in sending snmp inform packet

permalink · #1 (**permalink**) 03-05-2008

This is a multi-part message in MIME format.

--===============0486774712==
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0030_01C87EE6.32A2FF60"

This is a multi-part message in MIME format.

------=_NextPart_000_0030_01C87EE6.32A2FF60
Content-Type: text/plain;
charset="us-ascii"
Content-Transfer-Encoding: 7bit

Hi

We are facing a problem when trying to send an SNMPv3 INFORM PDU
to the snmptrapd

Following is what I have tried

1. Run the snmpTrapd daemon with following options

../snmptrapd -Le -f -d -C -c
"/home/meghana/snmp/share/snmp/snmptrapd_inform.conf

2. The configuration file snmptrapd_inform.conf has the following
entries

createUser myinformuser MD5 mypasswd AES mypasswd

authUser log myinformuser authNoPriv

ENGINE ID ISNT SPECIFIED AS THE RECEIVER OF SNMPINFORM MSG IS AUTHORITATIVE

3. It try to run the command

snmpinform -v 3 -u myinformuser -a MD5 -A mypasswd -l authNoPriv
10.100.10.61 42 coldStart.0

[I added some prints in the netsnmp source to trace the control flow]

With this I get the following error from snmptrapd daemon process and there
is a segmentation fault because of

Some incorrect error handling

a) snmptrapd does a snmp_read() from the socket

b) It then invokes snmp_create_sess_pdu(). This results in the call to
function snmpv3_parse()

c) Snmpv3_parse identifies the security model !=
SNMP_SEC_LEVEL_AUTHPRIV

d) It then calls usm_secmod_process_in_msg(), which results in a call
to usm_parse_security_parameters()

Which outputs engine ID len as 0 and secname = empty

e) Then the security name, engine ID, and security level are getting
cached

f) ISENGINEKNOWN() function gets called and it returns
SNMPERR_USM_UNKNOWNENGINEID

[return value = -48 ]

Because of this snmpv3_parse() returns failure

The control flows then results in a call to find_sec_mod() to handle any
special errors

AND THIS RESULTS IN SEGMENTATION FAULT !!!

4) I face the same issue (Point no 3) when I write my own application
(instead of snmpinform command)

In the application, I am filling the following members of session
information to pass the PDU

Fill in

i.
Version = 3

ii.
Peername and port

iii. Set
the default trap port to 162 using the statement
netsnmp_ds_set_int(NETSNMP_DS_LIBRARY_ID, NETSNMP_DS_LIB_DEFAULT_PORT,
SNMP_TRAP_PORT);

iv. Local
name

v.
Security engine ID = NULL and engineIDlen = 0

vi.
Security level = authnoPriv

vii.
Security model = default value

viii. Security
name = myinformuser, Len = string length of security name

ix.
securityAuthProto = MD5

x.
securityAuthProtoLen, securityAuthKeyLen are filled appropriately to
sizeof(usmHMACMD5AuthProtocol)/sizeof(oid) and USM_AUTH_KU_LEN

xi. We then
generate the key using generate_Ku()

xii.
securityPrivProto = AES

xiii. context
name = null

Open the session and fill the PDU and send using snmp_synch_response()

QUESTIONS:

1. why is the net snmp code for snmpv3_parse looking for an engine ID
when it is not required for snmpinform case (As the receiver is
authoritative in case of snmp inform msgs)

Hence it returns SNMPERR_USM_UNKNOWNENGINEID ???

2. Is the authuser directive required to be specified for snmp informs
in CONF file?

I tried removing it from conf file but here was no change in behavior

Regards,

Meghana

------=_NextPart_000_0030_01C87EE6.32A2FF60
Content-Type: text/html;
charset="us-ascii"
Content-Transfer-Encoding: quoted-printable

<html xmlns:v=3D"urn:schemas-microsoft-com:vml" =
xmlns:o=3D"urn:schemas-microsoft-com:office:office" =
xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
xmlns=3D"http://www.w3.org/TR/REC-html40">

<head>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Dus-ascii">
<meta name=3DGenerator content=3D"Microsoft Word 11 (filtered medium)">
<style>

</style>

</head>

<body lang=3DEN-US link=3Dblue vlink=3Dpurple>

<div class=3DSection1>

Hi<o:p></o:p>

<o:p> </o:p>

          =
  
We are facing a problem when trying to send an SNMPv3 INFORM PDU to the
snmptrapd <o:p></o:p>

Following is what I have =
tried<o:p></o:p>

<o:p> </o:p>

<ol style=3D'margin-top:0in' start=3D1 type=3D1>
<li class=3DMsoNormal style=3D'mso-list:l1 level1 lfo1'>Run the snmpTrapd =
daemon with
following options <o:p></o:p></l=
i>
</ol>

./snmptrapd=
-Le -f
-d -C -c =
"/home/meghana/snmp/share/snmp/snmptrapd_inform.conf<o:p></o:p></spa=
n>

<o:p> </o:p></fo=
nt>

<ol style=3D'margin-top:0in' start=3D2 type=3D1>
<li class=3DMsoNormal style=3D'mso-list:l1 level1 lfo1'>The configuration file =
snmptrapd_inform.conf =
 has the
following entries <o:p></o:p></li>
</ol>

createUser
myinformuser MD5 mypasswd AES mypasswd<o:p></o:p>

authUser =
log
myinformuser authNoPriv<o:p></o:p>

<o:p> </o:p></fo=
nt>

ENGINE ID ISNT SPECIFIED AS =
THE
RECEIVER OF SNMPINFORM MSG IS AUTHORITATIVE<o:p></o:p>

<o:p> </o:p></fo=
nt>

<o:p> </o:p>

<ol style=3D'margin-top:0in' start=3D3 type=3D1>
<li class=3DMsoNormal style=3D'mso-list:l1 level1 lfo1'>It try to run the =
command
  <o:p></o:p></li>
</ol>

snmpinform -v 3 -u
myinformuser -a MD5 -A mypasswd -l authNoPriv 10.100.10.61 42
coldStart.0     <o:p></o:p>

[I
added some prints in the netsnmp source to trace the control =
flow]<o:p></o:p></=
p>

<o:p> </o:p></fo=
nt>

With =
this I get the
following error from snmptrapd daemon process and there is a =
segmentation fault
because of <o:p></o:p>

 Some
incorrect error handling<o:p></o:p>

<o:p>&nbsp=
;</o:p>

<![if !supportLists]>a)       =
<![endif]>snmptrapd
does a snmp_read()    =
     
from the socket<o:p></o:p>

<![if !supportLists]>b)       =
<![endif]>It then
invokes snmp_create_sess_pdu(). =
This
results in the call to function  snmpv3_parse()<o:p></o:p></f=
ont>

<![if !supportLists]>c)       =
<![endif]>Snmpv3_parse
identifies the security model  !=3D =
SNMP_SEC_LEVEL_AUTHPRIV<o:p></o:p>

<![if !supportLists]>d)       =
<![endif]>It then
calls usm_secmod_process_in_msg(),
which results in a call to usm_parse_security_parameters()<o:p></o:p></sp=
an>

Which outputs engine ID len =
as 0 and
secname =3D empty<o:p></o:p>

<![if !supportLists]>e)       =
<![endif]>Then the
security name, engine ID, and security level are getting =
cached<o:p></o:p>

<![if !supportLists]>f)       
<![endif]>ISENGINEKNOWN() function =
gets called
and it returns SNMPERR_USM_UNKNOWNENGINEID<o:p></o:p>

[return value =3D -48 =
]<o:p></o:p>

Because of this snmpv3_parse() returns =
failure<o:p></o:p>

<o:p> </o:p></fo=
nt>

The control flows then =
results in a
call to find_sec_mod()   =
to
handle any special errors =
<o:p></o:p>

<o:p> =
</o:p>

AND THIS =
RESULTS IN
SEGMENTATION FAULT !!!<o:p></o:p>

<o:p> =
</o:p>

<o:p> =
</o:p>

<![if !supportLists]>4)       
<![endif]>I face the same issue =
(Point no 3)
when I write my own application (instead of snmpinform =
command)<o:p></o:p>

In the application, I am =
filling the
following members of session information to pass the =
PDU<o:p></o:p>

Fill in   =
<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   &nb=
sp;  
i.     
<![endif]>Version =3D =
3<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   &nb=
sp;
ii.     
<![endif]>Peername and =
port<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   
iii.     
<![endif]>Set the default trap port =
to 162
using the statement netsnmp_ds_set_int(NETSNMP_DS_LIBRARY_ID,
NETSNMP_DS_LIB_DEFAULT_PORT, =
SNMP_TRAP_PORT);<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   
iv.     
<![endif]>Local name =
<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   &nb=
sp; 
v.     
<![endif]>Security engine ID =3D NULL =
and
engineIDlen =3D 0<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   
vi.     
<![endif]>Security level =3D =
authnoPriv  <o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;  
vii.     
<![endif]>Security model =3D default =
value<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;
viii.     
<![endif]>Security name =3D myinformuser, Len =3D string =
length of
security name<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;  
ix.     
<![endif]>securityAuthProto =3D =
MD5<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;   &nb=
sp;
x.     
<![endif]>securityAuthProtoLen,
securityAuthKeyLen are filled appropriately to
sizeof(usmHMACMD5AuthProtocol)/sizeof(oid) and =
USM_AUTH_KU_LEN<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p;  
xi.     
<![endif]>We then generate the key =
using
generate_Ku()<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       &nbs p; 
xii.     
<![endif]>securityPrivProto =3D =
AES<o:p></o:p>

<![if !supportLists]>           &nbsp=
;        & nbsp;   =
        &n bsp;   &=
nbsp;       &nb sp;   &n=
bsp;       
xiii.     
<![endif]>context name =3D =
null<o:p></o:p>

    Open the =
session
and fill the PDU and send using snmp_synch_response()<o:p></o:p>=

<o:p> </o:p>

<o:p> </o:p>

          =
  
<o:p></o:p>

QUESTIONS:<o:p></o:p>

<ol style=3D'margin-top:0in' start=3D1 type=3D1>
<li class=3DMsoNormal style=3D'mso-list:l0 level1 lfo4'>why is the net snmp =
code for
snmpv3_parse looking for an engine ID when it is not required for
snmpinform case (As the receiver is authoritative in case of snmp =
inform
msgs) <o:p></o:p></li>
</ol>

Hence it returns
SNMPERR_USM_UNKNOWNENGINEID ???<o:p></o:p>

<o:p> </o:p></fo=
nt>

<ol style=3D'margin-top:0in' start=3D2 type=3D1>
<li class=3DMsoNormal style=3D'mso-list:l0 level1 lfo4'>Is the authuser directive required =
to be
specified for snmp informs in CONF file? =
<o:p></o:p></li>
</ol>

I tried =
removing it
from conf file but here was no change in =
behavior<o:p></o:p>

<o:p> </o:p></fo=
nt>

Regards,<o:p></o:p>

Meghana<o:p></o:p>

</div>

</body>

</html>

------=_NextPart_000_0030_01C87EE6.32A2FF60--

--===============0486774712==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
--===============0486774712==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

_______________________________________________
Net-snmp-users mailing list
Net-snmp-users@lists.sourceforge.net
Please see the following page to unsubscribe or change other options:
https://lists.sourceforge.net/lists/...net-snmp-users

--===============0486774712==--

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode