Adam Sweet's Wiki

add_a_user_to_the_sudoers_in_fedora

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Allow a User to use sudo You can allow a user to use sudo either by adding them to a group which is allowed to sudo, or by specifying the individual user. Use visudo to edit /etc/sudoers, it uses the system default editor, which is normally vi or vim if it's installed:

adding_a_route

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Adding a Network Route in Linux As root: Adding a Route route add -net 192.168.15.0 netmask 255.255.255.0 gw 192.168.1.1 First value is destination network address, then the destinsation's netmask and then your gateway for the destination network.

adding_kernel_modules_to_a_red_hat_installer_s_kernel

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:34+00:00

How to Add Kernel Modules to a Red Hat Installer's Kernel The following was copied verbatim from . I admit this freely, the reason for doing this is that I've had to do this a lot recently and academic pages have a habit of going away eventually. These instructions still seem to be valid for current RHEL/Fedora/Centos versions as of June 2008. On with the show

automatic_reboots_after_kernel_panics

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Automatic Reboots after Kernel Panics From To reboot automatically after a kernel panic, add kernel.panic = N to /etc/sysctl.conf. This specifies the kernel behaviour on a panic. By default, the kernel will not reboot after a panic, but this option will cause a kernel reboot after N seconds. For example following boot parameter will force to reboot Linux after 10 seconds:

basic_dns

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Basic DNS Setup Install bind9 and configured the server to run in a chroot as per here. On your primary names server, edit /var/lib/named/etc/bind/named.conf.local server <123.134.145.5> { provide-ixfr yes; }; #your first backup name server's IP server <123.134.145.6> { provide-ixfr yes; }; #your nth backup names server's IP zone "145.134.123.in-addr.arpa" in { type master; file "pz/123.134.145"; }; #Your IP range for reverse lookups zone "domain.tld" in { type master; file "pz/…

chrooted_dns

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

How to set up chrooted DNS on Ubuntu Dapper Taken from Run apt-get install bind9 For security reasons we want to run BIND chrooted so we have to do the following steps: /etc/init.d/bind9 stop Edit the file /etc/default/bind9 so that the daemon will run as the unprivileged user bind, chrooted to /var/lib/named.

cisco

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:34+00:00

Cisco Stuff VLANs on 2950 switch

command_line

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Stuff About the Command Line * Midnight Commander Tricks * Split an Mbox file on the From Line * Add a user to the sudoers in Fedora * Using screen for shared console access

command_line_http_proxy

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Command Line HTTP Proxy http_proxy=http://username:password@host:port/ export http_proxy

computers

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Stuff About Computers * Linux * Server * Desktop * Mail * DNS * Cisco * HTTP Stuff

configuring_mailman_for_ubuntu

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Configuring [[http://www.gnu.org/software/mailman/|Mailman]] for Ubuntu Taken from Draft - Started 17 December 2005 Released to the unsuspecting world - 21 December 2005 Latest minor revision - 24 August 2006 at 01:30 PM Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License. Software selected

create_your_own_anti-virus_signatures_with_clamav

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Create Your Own Anti-Virus Signatures with ClamAV I use ClamAV on my own mail servers, I've also used it at work alongside several commercial AV engines and every now and again there will be a viral attachment that none of the AV engines catch, especially when a new threat is released. As a Linux user, most virus and malware threats mean little to me, however if you are responsible for Windows users then you need to be on top of the game.

debian_rc.local_equivalent

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Debian rc.local Equivalent Taken from In many distributions you can add commands to run certain programs at the end of the boot process after all system services have been started into the /etc/rc.d/rc.local file, however there is no such file in a Debian system. Here is the way to accomplish the same thing the debian way:

dns

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

DNS Stuff about DNS servers... * How to set up chrooted DNS on Ubuntu Dapper * Basic DNS

dnsbls

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

DNSBLs DNSBLs are DNS Black Lists. They are lists of IP addresses known for spamming or which are part of known spammy networks. As most spam these days is generated by malware infested Windows PCs, some blacklists are simply lists of consumer grade broadband IP addresses, such as your home ADSL or cable connection and are registered by the ISPs which own them. Consequently, running a mail server on a consumer grade connection is not ideal as you may well get blocked. My IP address at home is l…

exim

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:34+00:00

Exim * Exim Commands

exim_commands

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Exim Commands exim -bpc => no of emails currently in the mail queue exim -bpr => Print mail queue exim -M email-id => Force delivery of one message exim -qf => Force another queue run exim -qff => Force another queue run and attempt to flush the frozen message exim -Mvl messageID => View the log for the message exim -Mvb messageID => View the body of the message exim -Mvh messageID => View the header of the message exim -Mrm messageID => Remove message without sending any error message exim -Mg …

get_sendmail_to_log_the_subject_line

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Get Sendmail to Log the Subject Line of an E-mail Edit /etc/mail/sendmail.mc After the MAILER () definitions, add: LOCAL_CONFIG Klog syslog HSubject: $>+CheckSubject LOCAL_RULESETS SCheckSubject R$* $: $(log Subject: $1 $) $1 That's a tab after the

greylisting

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Greylisting with Exim For greylisting with Exim or Vexim, try the following:: Install greylistd via apt for Debian and derivatives or ATrpms for Fedora/Red Hat and add your exim user to the greylist group, make sure /var/lib/greylistd/whitelist-hosts is group readable, configure greylistd (set your delay time in the main greylistd config file and add your own hosts to /var/lib/greylistd/whitelist-hosts) and insert the following into vexim-acl-check-rcpt.conf on Vexim, or for plain Exim, in the…

http_stuff

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

HTTP Stuff * PHP Redirects

ip_forwarding

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

IP Forwarding To enable a machine to act as a gateway for a network: echo "1" > /proc/sys/net/ipv4/ip_forward iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -j MASQUERADE Where 192.168.1.0/24 is the network which will use this machine as a gateway.

ipmi_on_linux

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Running IPMI on Linux What is IPMI? IPMI is standard which allows remote server management, primarily developed by Intel. IPMI cards, known as Baseboard Management Cards (BMCs) are primitive computers in their own right and are operational all the time, so long as the server has a power source. The server itself does not need to be powered on, or the operating system operational for the BMC to work, it just needs a power source to be connected to the server.

kernel_stuff

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Kernel Stuff Adding kernel modules to a Red Hat installer's kernel

linux

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Stuff About Linux * Scripting * Networking * Command Line * System Control * System Level Accounting and Monitoring * Kernel Stuff * Managing Linux Software RAID

mail

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Stuff About Mail Servers * Exim * Virus Filtering * Greylisting * DNSBLs (DNS Black Lists) * Configuring Mailman for Ubuntu * Using Exim Behind a NATed Connection * Get Sendmail to log the subject line * Create Your Own Anti-Virus Signatures With ClamAV

managing_linux_software_raid

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Managing Linux Software RAID Below are some notes on using Linux Software RAID. It's not complete yet of course :) Marking a damaged disk as failed: mdadm --manage --set-faulty /dev/md1 /dev/sdd1 Removing the damaged disk from the array: mdadm /dev/md1 -r /dev/sdd1

midnight_commander_tricks

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Midnight Commander Tricks Using FTP in mc: cd /#ftp:user@machine.edu

networking

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:34+00:00

Stuff About Networking on Linux * Adding a Route * IP Forwarding * VNC over SSH * RDP over SSH * Linux Wake on LAN client * Command Line HTTP Proxy

php_redirects

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

PHP Redirects To create a redirect in PHP from one location to another create an index.php containing the following: "); ?> Such as: or

quick_date_based_archiving

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Quick Date Based Archiving su -c 'tar czf /tmp/etc-`date +%F`.tar.gz /etc' mv /tmp/etc-*.tar.gz ~

quick_grep_tricks

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Quick Grep Tricks Grep for x or y, eg: ls -lR | grep "x\|y" Removing blank lines from output: grep -v "^$" filename

rdp_over_ssh

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

RDP Over SSH This shows how to use Windows Remote Desktop v5 over SSH over the Internet. It helps if you're running Linux, SSHing to another Linux machine and then forwarding an RDP connection to a Windows box. Set up your initial tunnel from your own Linux box to another remote one on the Windows network:

redirecting_shell_output_to_dev_null

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:34+00:00

Redirecting Shell Output to /dev/null ./example.pl > /dev/null 2>&1 Sends stdout to /dev/null and then sends stderr to where ever stdout goes to.

scripting

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Stuff About Scripting * Redirecting shell output to /dev/null * Quick Grep Tricks * Debian rc.local Equivalent * Quick date based archiving * Sort a list of IP addresses

server

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Stuff About Servers * IPMI on Linux * TFTP on Ubuntu * Apache SSL on Ubuntu * Simple SNMP * Using SSL with Exim 4 on Debian

simple_snmp

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Simple SNMP on Windows and Linux This page describes a simple SNMP setup for Linux and Windows with graphs for output. It doesn't describe SNMP traps, but maybe will in a future update. Basics Simple Network Management Protocol is a protocol used to querying hosts for information about their status, such as CPU usage, bandwidth usage, memory usage and so on. SNMP uses UDP port 161. There are 3 SNMP versions: 1, 2c and 3. Put simply, 2c offers more information than 1, but both pass the communi…

sort_a_list_of_ip_addresses

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Sort a List of IP Addresses sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4 or | sort -n -t . -k 1,1 -k 2,2 -k 3,3 -k 4,4

split_an_mbox_file_on_the_from_line

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Split an Mbox file on the From Line I've had to do this when you are using an mbox mail spool and you get an enormous mail (in my case usually some automated data import) which is too large to transfer in a reasonable period causing you to not be able to download any mail because there is a huge one in the way.

start

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Adam Sweet's Wiki OK, here is my Wiki, a place to brain dump. Hopefully you will find it useful, though I make no promises that you will, or that the content will be correct. It will primarily be a dumping ground for snippets of config and useful information that I expect to call upon again, or which other people might find useful.

supermicro_ipmi_v2.0_on_ubuntu

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Running IPMI on Linux What is IPMI? IPMI is standard which allows remote server management, primarliy developed by Intel. IPMI cards, known as Baseboard Management Cards (BMCs) are primitive computers in their own right and are operational all the time, so long as the server has a power source. The server itself does not need to be powered on, or the operating system operational for the BMC to work.

system_control

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Stuff About Controlling the System * Automatic Reboots after Kernel Panics * Using Magic SysReq Keys in an Emergency * Assigning a process to a CPU or core (aka processor affinity) * When Apache Runs Out of Semaphores

system_level_accounting_and_monitoring

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:34+00:00

System Level Monitoring and Accounting * iostat man page * Process Accounting * Auditing file changes

tftp_on_ubuntu

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Setting up TFTP on Ubuntu Taken from . 1. Install tftpd and related packages. $ sudo apt-get install xinetd tftpd tftp 2. Create /etc/xinetd.d/tftp and put this entry: service tftp { protocol = udp port = 69 socket_type = dgram wait = yes user = nobody server = /usr/sbin/in.tftpd server_args = -s /tftpboot disable = no }

using_exim_behind_a_nated_connection

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Using Exim behind a NATed Connection When using Exim behind a NATed connection, such as a consumer grade ADSL or Cable line, where the Exim machine's IP address is a local address which isn't routable and the router or firewall uses port forwarding to send the SMTP and POP3/IMAP ports to the correct machine, you may well get mailing loops where Exim tries to forward a mail to the MX record specified in

using_magic_sysreq_keys_in_an_emergency

Anonymous (anonymous@undisclosed.example.com) — 2025-08-08T17:06:48+00:00

Using Magic SysReq Keys in an Emergency From The Linux kernel includes magic system request keys. It was originally developed for kernel hackers, however you can use them to reboot or shutdown the machine safely (remember safe reboot/shutdown == flush filesystem buffers and unmount file system and then reboot so that data loss can be avoided).

using_screen_for_shared_console_access

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Using screen for Shared Console Access Based on To share access with another person, the screen tool can be used. Log in to the machine where you want to share a console user1$ screen -S SessionName SessionName can be any easy string. Ctrl-a :multiuser on

using_ssl_with_exim_4_on_debian

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

Using SSL with Exim 4 and Courier IMAP/POP3 on Debian Here I will be setting up SSL keys with Exim 4 and Courier IMAP and POP3 under Debian to secure the sending and retrieval of emails and username and password details to my server. I will be using SSL certificates from

vlans_on_2950_switch

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

VLANs on 2950 Switch version 12.1 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption hostname myname enable secret mypass ip subnet-zero ip domain-name mydomain.co.uk ip name-server xyz.xyz.xyz.xyz ip name-server xyz.xyz.xyz.xyz spanning-tree extend system-id interface FastEthernet0/1 description WAN switchport mode trunk no ip address duplex full speed 100 spanning-tree portfast interface FastEthernet0/2 description vlan2 s…

vnc_over_ssh

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:32+00:00

Using VNC Over SSH Setting it up for the first time * Install vncserver on the destination machine. * Run vncserver once and note the session number given (:1 if nobody else is using VNC on the machine). It will ask you to create a vnc password so do so. Example (minus the password part):

when_apache_runs_out_of_semaphores

Anonymous (anonymous@undisclosed.example.com) — 2016-11-25T22:38:33+00:00

What to Do When Apache Runs Out of Semaphores Taken from If you get this error message when trying to start Apache, then you're out of semaphores: #apachectl start Ouch! ap_mm_create(1048576, "/var/run/httpd.mm.22903") failed Error: MM: mm:core: failed to acquire semaphore (No space left on device): OS: Invalid argument /usr/sbin/apachectl start: httpd could not be started