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Bug#546854: marked as done (openssh-server: has unspecified limit for number of sessions tunnelled through controlmaster)

Your message dated Tue, 2 Nov 2010 20:56:40 +0100
with message-id <20101102195640.GA14773@nechayev.zugschlus.de>
and subject line Re: Bug#546854: MaxSessions in sshd_config
has caused the Debian Bug report #546854,
regarding openssh-server: has unspecified limit for number of sessions tunnelled through controlmaster
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
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-- 
546854: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=546854
Debian Bug Tracking System
Contact owner@bugs.debian.org with problems
--- Begin Message --- 
Package: openssh-server
Version: 1:5.1p1-7
Severity: normal

Hi,

I can only reach most of my systems through a dual-homed host which I
access via proxycommand ssh dhhost socket %h %p. When I use
controlmaster, there seems to be a rather low session limit of around
ten sessions which can be tunneled through.

When this limit is reached, the server logs "error: no more sessions"
and the client holding the controlmaster spews "open failed:
administratively prohibited: open failed" to its console.

In some cases, closing one of the sessions does not immediately free
up a "slot", but new connections become possible after waiting a few
minutes.

Googling for the error message suggests that there is a macro
MAX_SESSIONS which can be increased, but the current sources only
contain this string inside debian/changelog when it was documented
that this macro was increased to 64 somewhen in 2007. So I suspect
that this is now dynamically allocated, eliminating the macro from the
sources.

However, the limit remains and is a rather severe limitation
especially when a security update needs to be rolled out (I do this in
parallel and frequently hit this limit).

Greetings
Marc

-- System Information:
Debian Release: squeeze/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: i386 (i686)

Kernel: Linux 2.6.30.5-nc8000 (PREEMPT)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash

Versions of packages openssh-server depends on:
ii  adduser                3.110             add and remove users and groups
ii  debconf [debconf-2.0]  1.5.27            Debian configuration management sy
ii  dpkg                   1.15.3.1          Debian package management system
ii  libc6                  2.9-25            GNU C Library: Shared libraries
ii  libcomerr2             1.41.8-2          common error description library
ii  libgssapi-krb5-2       1.7dfsg~beta3-1   MIT Kerberos runtime libraries - k
ii  libk5crypto3           1.7dfsg~beta3-1   MIT Kerberos runtime libraries - C
ii  libkrb5-3              1.7dfsg~beta3-1   MIT Kerberos runtime libraries
ii  libpam-modules         1.0.1-10          Pluggable Authentication Modules f
ii  libpam-runtime         1.0.1-10          Runtime support for the PAM librar
ii  libpam0g               1.0.1-10          Pluggable Authentication Modules l
ii  libselinux1            2.0.85-1          SELinux shared libraries
ii  libssl0.9.8            0.9.8k-4          SSL shared libraries
ii  libwrap0               7.6.q-18          Wietse Venema's TCP wrappers libra
ii  lsb-base               3.2-23            Linux Standard Base 3.2 init scrip
ii  openssh-blacklist      0.4.1             list of default blacklisted OpenSS
ii  openssh-client         1:5.1p1-7         secure shell client, an rlogin/rsh
ii  procps                 1:3.2.8-1         /proc file system utilities
ii  zlib1g                 1:1.2.3.3.dfsg-15 compression library - runtime

Versions of packages openssh-server recommends:
ii  openssh-blacklist-extra       0.4.1      list of non-default blacklisted Op
ii  xauth                         1:1.0.3-2  X authentication utility

Versions of packages openssh-server suggests:
ii  molly-guard                  0.4.4-2     protects machines from accidental 
pn  rssh                         <none>      (no description available)
ii  ssh-askpass                  1:1.2.4.1-7 under X, asks user for a passphras
pn  ufw                          <none>      (no description available)

-- debconf information excluded

--- End Message ---
--- Begin Message --- 
On Mon, Nov 01, 2010 at 02:30:30PM +0100, Wessel Dankers wrote:
> Have you tried increasing the MaxSessions configuration parameter
> in /etc/ssh/sshd_config to something higher than the default 10?

In fact, I found that setting a few months ago and forgot to close
this bug. Thanks for the heads-up

Greetings
Marc

-- 
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--- End Message ---
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