Discuss August 2011

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222 participants
208 discussions

Centos6(64) SSH sessions fail irregularly [SOLVED]
by david 10 Aug '11

10 Aug '11

Folks I just installed a centos6 system on a 64-bit box. My methods include remote administration, using ssh from a windows machine. I use this method successfully on several Centos5 boxes and one Centos6 (32bit) machine as well. However, on this latest one, I get inconsistent results with ssh. This is a server, SELINUX is disabled, it's command line only, and I have installed sendmail, apache, vsftpd (but haven't used the last two yet). The machine is connnected internally only (behind NAT), so is invisible to the outside world. In a successful use of SSH just after installing the needed software, I installed the DSA keys so no password is used. Subsequent to that, and at seemingly unpredictable frequent attempts, I get results such as a) A successful SSH login as desired. Variious commands, sucn as "ls" and such, work fine. b) A successful login, but a write failure with whatever I enter next c) Connection refused d) A request for password (followed by failure) I can't seem to connect these various errors with any activity on the server -- I'm monitoring /var/log/messages /var/log/secure and /var/log/audit/audit.log, on a terminal directly attached to the server. The server, and my windows box (which is my admin box) are on the same internal IPV4 network (192.168.xxx.xxx), all controlled by a Centos5 gateway running just fine which provides DHCP and NAT when needed. I haven't been able to correlate these failures with anything I do; there's no indication on the server that anything is happening. Of course, when the SSH login succeeds, there's a notation in the logs, but no evidence of the failures. I tend to get "best" results after a bootstrap, With no evidence of anything abnormal showing up in the logs, it's not clear where to look. I would appreciate some clues as to where to look next. The server seems to have functioning internet access through the gateway. I can easily redo the install if needed. The hardware was previously running Win7, so I suspect it's good hardware. It's a roll-you-own machine built with components from Fry's, so don't ask me for the model name :-) I'd appreciate advice or guidance. David Kurn SOLUTION: (with embarrassment) It turns out that one of the Ethernet switches in the path was not behaving properly. I removed it, and the problem disappeared. Sorry to have raised a red-flag ... the problem has been bugging me for 5 days and only today did I look at the switch.

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Increase audio volume
by Juan C. Valido 10 Aug '11

10 Aug '11

Is there a way to increase the audio volume on CentOS 6. I have it set at the max and still very low. Thank you.

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Centos6(64) SSH sessions fail irregularly
by david 10 Aug '11

10 Aug '11

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sieveshell fails to start on CentOS 6.0
by Harold Pritchett 10 Aug '11

10 Aug '11

I don't know if this is the right place to report this or not. I am building a new server on a 64 bit CentOS 6.0 platform. [root@newmick ~]# cat /etc/redhat-release CentOS Linux release 6.0 (Final) [root@newmick ~]# uname -a Linux newmick.halshome.net 2.6.32-71.29.1.el6.x86_64 #1 SMP Mon Jun 27 19:49:27 BST 2011 x86_64 x86_64 x86_64 GNU/Linux Mail subsystem consists of: sendmail spamassassin spamass-milter cyrus-imap All of these appear to be working. Mail sent to the system appears in the inbox of the user it is sent to. My problem: I am unable to get the cyrus sieve to work. Attempting to run sieveshell to load the filter fails as shown below. [harold@newmick ~]$ sieveshell localhost connecting to localhost unable to connect to server at /usr/bin/sieveshell line 170. [harold@newmick ~]$ I have googled the error message and can find entries going back as far as the early 2000's. Nothing recent which seems to apply. Details: [root@newmick etc]# telnet localhost sieve Trying ::1... Connected to localhost. Escape character is '^]'. "IMPLEMENTATION" "Cyrus timsieved v2.3.16-Fedora-RPM-2.3.16-6.el6" "SASL" "" "SIEVE" "comparator-i;ascii-numeric fileinto reject vacation imapflags notify envelope relational regex subaddress copy" "STARTTLS" OK [root@newmick etc]# telnet 127.0.0.1 sieve Trying 127.0.0.1... Connected to 127.0.0.1. Escape character is '^]'. "IMPLEMENTATION" "Cyrus timsieved v2.3.16-Fedora-RPM-2.3.16-6.el6" "SASL" "" "SIEVE" "comparator-i;ascii-numeric fileinto reject vacation imapflags notify envelope relational regex subaddress copy" "STARTTLS" OK The following subsystems are running: [root@newmick ~]# service --status-all | grep running abrtd (pid 2538) is running... acpid (pid 1768) is running... atd (pid 2557) is running... auditd (pid 2604) is running... automount (pid 1894) is running... avahi-daemon (pid 1743) is running... crond (pid 2546) is running... cyrus-imapd (pid 13884) is running... hald (pid 1777) is running... ip6tables: Firewall is not running. iptables: Firewall is not running. irqbalance (pid 1577) is running... mdmonitor (pid 1621) is running... messagebus (pid 1731) is running... rpc.statd (pid 1609) is running... rpcbind (pid 1591) is running... rpc.idmapd (pid 1656) is running... rsyslogd (pid 1536) is running... saslauthd (pid 2472) is running... sendmail (pid 2510) is running... sm-client (pid 2519) is running... slapd (pid 1877) is running... spamass-milter (pid 2528) is running... spamd (pid 9308) is running... openssh-daemon (pid 1912) is running... xinetd (pid 1920) is running... [root@newmick ~]# Notes on the above... Firewall is NOT running. saslauthd is running. slapd is running. No errors in the selinux audit logs. Configuration files look like this: [root@newmick etc]# cat /etc/imapd.conf configdirectory: /var/lib/imap partition-default: /var/spool/imap admins: cyrus sievedir: /var/lib/imap/sieve sendmail: /usr/sbin/sendmail hashimapspool: true sasl_pwcheck_method: saslauthd sasl_mech_list: PLAIN tls_cert_file: /etc/pki/tls/certs/cyrus.pem tls_key_file: /etc/pki/tls/certs/cyrus.pem tls_ca_file: /etc/pki/tls/certs/ca-bundle.crt # uncomment this if you're operating in a DSCP environment (RFC-4594) # qosmarking: af13 [root@newmick etc]# [root@newmick etc]# cat /etc/cyrus.conf # standard standalone server implementation START { # do not delete this entry! recover cmd="ctl_cyrusdb -r" # this is only necessary if using idled for IMAP IDLE idled cmd="idled" } # UNIX sockets start with a slash and are put into /var/lib/imap/sockets SERVICES { # add or remove based on preferences # imap cmd="imapd" listen="imap" prefork=5 imaps cmd="imapd -s" listen="imaps" prefork=1 # pop3 cmd="pop3d" listen="pop3" prefork=3 # pop3s cmd="pop3d -s" listen="pop3s" prefork=1 sieve cmd="timsieved" listen="sieve" prefork=0 # these are only necessary if receiving/exporting usenet via NNTP # nntp cmd="nntpd" listen="nntp" prefork=3 # nntps cmd="nntpd -s" listen="nntps" prefork=1 # at least one LMTP is required for delivery # lmtp cmd="lmtpd" listen="lmtp" prefork=0 lmtpunix cmd="lmtpd" listen="/var/lib/imap/socket/lmtp" prefork=1 # this is only necessary if using notifications # notify cmd="notifyd" listen="/var/lib/imap/socket/notify" proto="udp" prefork=1 } EVENTS { # this is required checkpoint cmd="ctl_cyrusdb -c" period=30 # this is only necessary if using duplicate delivery suppression, # Sieve or NNTP delprune cmd="cyr_expire -E 3" at=0400 # this is only necessary if caching TLS sessions tlsprune cmd="tls_prune" at=0400 } [root@newmick etc]# What other information do you need? Is there something obvious I have missed? I tried to send this with a "rpm -qa" attached, but my mail server timed out. too big I guess... Harold

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selinux prohibiting sssd usage
by Paul Heinlein 10 Aug '11

10 Aug '11

I've got a CentOS 6 machine that's slated to go into production providing some web and development-repository services. Part of the environment is gitweb, which works as expected with one glitch: SELinux doesn't allow gitweb.cgi to query sssd to display who owns the repositories. The audit log entries are pretty straightforward, e.g., type=AVC msg=audit(XXXXXXXXXXXX): avc: denied { search } for pid=XXXX comm="gitweb.cgi" name="sss" dev=XXX ino=XXXXXXXXXXX scontext=unconfined_u:system_r:httpd_git_script_t:s0 tcontext=system_u:object_r:sssd_var_lib_t:s0 tclass=dir I'll use audit2allow to build a custom policy if need be, but what I'd really like to hear is that there's an SELinux boolean that can be tweaked or a file context that can be altered to make things work as expected. -- Paul Heinlein <> heinlein(a)madboa.com <> http://www.madboa.com/

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setting up bare minimal CentOS VM
by Rudi Ahlers 10 Aug '11

10 Aug '11

Hi all, I need to setup a real bare minimum CentOS Virtual Machine, but with normal internet / network access. i.e. I need SSH, Mutt, Links, lynx, ping, tracert, dig, iptables, etc. Does anyone know where (if?) I can get a list of applications which gets installed with CentOS 6 if every option is deselected in the installer so that I can see what I can remove which isn't really necessary once installed? -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532

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Re: [CentOS] Two Samba Servers and Rsync
by Tom Diehl 10 Aug '11

10 Aug '11

On Tue, 9 Aug 2011, John R Pierce wrote: > On 08/09/11 12:50 PM, Railic Njegos wrote: >> I plan to use rsync to sync data from second to first server. It is OK ? >> Any suggestion ? > > rsync doesn't much tolerate network glitches in my experience. its > also a incremental file backup/copy, and won't be doing a 'snapshot' so > if any of these files you're copying are things that are randomly > updated like a database, its quite possible for the copy to be useless. > > as a backup strategy, having a single copy that you overwrite when you > make a new copy is weak. you have no history, you can't recover the file > that the user overwrote 2 days ago and forgot to tell you until today, > as you just overwrote your backup with his mistake last night. There is also rdiff-backup if you need history. Of course it is not a perfect solution either. Any solution is going to have trade offs. Regards, -- Tom Diehl tdiehl(a)rogueind.com Spamtrap address mtd123(a)rogueind.com

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keyboard problem
by bcb 10 Aug '11

10 Aug '11

OK, I know what I'm doing is "officially unsupported", but perhaps someone has some suggestions... I have a CentOS 5.6 system running as a virtual machine using VMware player. I cloned the system, booted the clone to make sure everything worked after cloning, it did. I then booted off a CentOS 6 ISO and did an upgrade (I know, unsupported!). I've got the system to the point where everything works except the keyboard. If I boot to a command line, it works, as soon as X gets involved, there is no response at all from the keyboard. The on-screen keyboard does work. The physical keyboard works in the host OS and all of the other guest OSes on the machine. It works in the original CentOS 5.6 VM. I'm at a loss and would love some advice on where to look next. Thanks! Bruce

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tweek startup and logon
by Johan Vermeulen 10 Aug '11

10 Aug '11

Dear All, CentOs 6 is great, but I would like to get back 2 things from 5.6 : how can I always see the text lines during startup? (so no graphical screen ) how can I *not *see all the users on the system when loging on? (so that users also have to remember their username) thanks for any advise. James -- Johan Vermeulen IT-medewerker Caw De Kempen johan.vermeulen(a)cawdekempen.be 0479.82.01.41 Opensource Software is the future.

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Centos6 Migration glitch - Samba
by david 10 Aug '11

10 Aug '11

Folks My experiments have shown that Samba behaves differently in Centos 5.6 and Centos 6 (updated). In Centos 5, service smb restart restarts both smb and nmb. In Centos 6, however, it restarts only smb. REMEDY: a) Make sure that both services running b) Issue chkconfig smb on chkconfig nmb on IS THIS THE DESIRED BEHAVIOR I have no idea if this difference is a "bug" or a "feature", and leave it to others to determine that. David Kurn

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Discuss August 2011