Author: admin

Postfix DEBUGGING 1.) If things are acting strangely here is a simple and quick first step that could save you a lot of time. * TO CHECK THE CURRENT CONFIGURATION: /usr/sbin/postfix check * validates the Postfix mail system configuration and will * warn about bad directory/file ownership or permissions, and * create missing directories. 2.) […]

dhcpd.conf netbios node types The following is a list of netbios node types, for the ISC dhcp server (should be pertinent to any DHCP server though). # These are the node types for netbios options: #1 = B-node, 2 = P-node, 4 =M-node, 8 = H-node option netbios-node-type 8; # default NetBIOS name resolution mode […]

DENY AND ALLOW USERS IN OPENSSH By default, OpenSSH allows logins for anyone with a valid password and shell. However, on a Linux system with numerous system accounts, this can be problematic. Imagine that you’re running a mail server, where each mail user has a system account. If you set up an e-mail account for […]

Create an iso image of a directory of files on Linux. mkisofs -J -R -v -T -o image.iso cdrom/ Will build an ISO image of all the files in the /cdrom directory.

Installing PERL modules perl -MCPAN -e “shell” Once in the shell: install Some::Module (in the above shell) or using MCPAN without the shell: perl -MCPAN -e “install ‘Some::Module'” or using cpan directly: cpan -i ‘Some::Module’

Linux lsattr chattr I was trying to remove an old file from my computer but for some reason was unable to delete it. When I tried to remove it I got the message “rm: cannot unlink ‘filename’: Operation not permitted” I was logged in as root when I tried this command – again unable to […]

Using awk to filter specific information. # print column one using space as a separator grep /var/log/maillog.1 | awk ‘{print $1}’ # print column four using : as a separator grep /var/log/maillog.1 | awk -F “:” ‘{print $4}’ Use grep -i for case insensitive search.

How to obtain a new root.cache / root.hints file Download via ftp: wget -O named.cache ftp://ftp.internic.net/domain/named.cache Or: Use dig to download records from root server. dig @198.41.0.4 > root.cache Note: Using dig does not seem to get IPV6 records.

How to remove duplicate packages in rpm rpm -e –allmatches mysql –nodeps Note: This also uninstalls the package(s).

Linux library info ldd `which smbd` | grep cups e.g. # ldd `which smbd` | grep cups libcups.so.2 => /usr/lib/libcups.so.2 (0x00f76000) # ldd `which perl` | grep perl libperl.so => /usr/lib/perl5/5.8.5/i386-linux-thread-multi/CORE/libperl.so (0x00994000)