Bug 110931 - snmpd opens port 199 (smux) even if smuxpeer isn't present
Summary: snmpd opens port 199 (smux) even if smuxpeer isn't present
Keywords:
Status: CLOSED NOTABUG
Alias: None
Product: Red Hat Enterprise Linux 3
Classification: Red Hat
Component: net-snmp
Version: 3.0
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Radek Vokál
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2003-11-25 16:41 UTC by Bastien Nocera
Modified: 2007-11-30 22:06 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2004-08-17 08:09:24 UTC
Target Upstream Version:


Attachments (Terms of Use)

Description Bastien Nocera 2003-11-25 16:41:39 UTC
-(~)-> sudo rpm -Uvh /tmp/net-snmp-5.0.8-11.i386.rpm
/tmp/beecrypt-3.0.1-0.20030630.i386.rpm
Preparing...               
########################################### [100%]
   1:beecrypt              
########################################### [ 50%]
   2:net-snmp              
########################################### [100%]
-(~)-> chkconfig --list | grep snmp
snmpd           0:off   1:off   2:off   3:off   4:off   5:off   6:off
snmptrapd       0:off   1:off   2:off   3:off   4:off   5:off   6:off
-(~)-> sudo service snmpd start
Starting snmpd:                                            [  OK  ]
-(~)-> netstat -a | grep smux
tcp        0      0 *:smux                  *:*                     LISTEN
-(~)-> grep smux /etc/snmp/snmpd.conf
-(~)->

Comment 1 Radek Vokál 2004-08-17 08:09:24 UTC
Smux is automatically initiated by snmpd

http://www.networksorcery.com/enp/rfc/rfc1227.txt

Comment 2 Jan Iven 2005-12-06 11:38:41 UTC
As per RFC1227:
  [..] This mechanism would be local to the host.

We open a TCP port bound to default address, i.e. visible on the network in general.
In addition, SMUX appears to have been deprecated in favour of agentX,
RFC2741/2, and apparently would only be useful for some legacy applications. The
code is old, and opening SMUX even if not configured is exposing the host to
unneccesary risk (even if access control is supposed to happen on such
connections). Binding to localhost only would also enhance the host security.

A patch exists at
http://lists.quagga.net/pipermail/quagga-dev/2004-October/001617.html
that promises to turn off SMUX unless (one or more) smuxpeers have explicitly
been configured.

"How to turn off SMUX" is actually a FAQ for net-snmp, see
http://www.net-snmp.org/docs/FAQ.html#How_can_I_turn_off_SMUX_support_ (the
workaround there is probably nothing one would like on a production system).

Please re-open.


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