TTL for BGP packets

By default, an eBGP message has IP TTL of 1. When neighbors do not have a common network, or an eBGP router uses its loopback interface as an update source, the TTL value needs to be adjusted.

(config-router)# bgp neighbor IP_ADDR ebgp-multihop TTL_VALUE

In contrast, iBGP message has TTL of 255, and there is no need for extra configuration when using a loopback interface as an update source.

eBGP OPEN Message

iBGP OPEN Message

Mac OS X: Path to 802.11 utility command

/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport

"/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport" will display the usage.

Usage: airport <interface> <verb> <options>
<interface>
If an interface is not specified, airport will use the first AirPort interface on the system.
<verb is one of the following:
prefs If specified with no key value pairs, displays a subset of AirPort preferences for
the specified interface.
Preferences may be configured using key=value syntax. Keys and possible values are specified below.
Boolean settings may be configured using 'YES' and 'NO'.
DisconnectOnLogout (Boolean)
JoinMode (String)
Automatic
Preferred
Ranked
Recent
Strongest
JoinModeFallback (String)
Prompt
JoinOpen
KeepLooking
DoNothing
RememberRecentNetworks (Boolean)
RequireAdmin (Boolean)
RequireAdminIBSS (Boolean)
RequireAdminNetworkChange (Boolean)
RequireAdminPowerToggle (Boolean)
WoWEnabled (Boolean)
logger Monitor the driver's logging facility.
sniff If a channel number is specified, airportd will attempt to configure the interface
to use that channel before it begins sniffing 802.11 frames. Captures files are saved to /tmp.
Requires super user privileges.
debug Enable debug logging. A debug log setting may be enabled by prefixing it with a '+', and disabled
by prefixing it with a '-'.
AirPort Userland Debug Flags
DriverDiscovery
DriverEvent
Info
SystemConfiguration
UserEvent
PreferredNetworks
AutoJoin
IPC
Scan
802.1x
Assoc
Keychain
RSNAuth
WoW
P2P
Roam
BTCoex
AllUserland - Enable/Disable all userland debug flags
AirPort Driver Common Flags
DriverInfo
DriverError
DriverWPA
DriverScan
AllDriver - Enable/Disable all driver debug flags
AirPort Driver Vendor Flags
VendorAssoc
VendorConnection
AllVendor - Enable/Disable all vendor debug flags
AirPort Global Flags
LogFile - Save all AirPort logs to /var/log/wifi.log
<options> is one of the following:
No options currently defined.
Examples:
Configuring preferences (requires admin privileges)
sudo airport en1 prefs JoinMode=Preferred RememberRecentNetworks=NO RequireAdmin=YES
Sniffing on channel 1:
airport en1 sniff 1

LEGACY COMMANDS:
Supported arguments:
 -c[<arg>] --channel=[<arg>]    Set arbitrary channel on the card
 -z        --disassociate       Disassociate from any network
 -I        --getinfo            Print current wireless status, e.g. signal info, BSSID, port type etc.
 -s[<arg>] --scan=[<arg>]       Perform a wireless broadcast scan.
  Will perform a directed scan if the optional <arg> is provided
 -x        --xml                Print info as XML
 -P        --psk                Create PSK from specified pass phrase and SSID.
  The following additional arguments must be specified with this command:
                                  --password=<arg>  Specify a WPA password
                                  --ssid=<arg>      Specify SSID when creating a PSK
 -h        --help               Show this help

Link: Cisco official design guide

Design zone for security by Cisco
http://www.cisco.com/en/US/netsol/ns744/networking_solutions_program_home.html

Cisco IOS key bindings

Cisco IOS implements UNIX shell like key bindings. The following is what I often use. Once you get used to it, C-a or C-b is going to be your headache when connecting to a cisco device with GNU screen or a window multiplexer (e.g. tmux, byobu),  ;)

GENERAL
TAB key
Completes a partially typed CLI command
?
Displays help
C-p, Up arrow, C-n, Down arrow
Displays your previous command (history)
C-^
Breaks current processing command

C-r
Redisplays the current command line
C-z
Takes you back to privileged EXEC Mode

Deleting an Input
C-u
Deletes all characters before the cursor
C-w
Deletes a word (behind the cursor)

C-h

Deletes a character (behind the cursor)

Moving the Cursor Quickly

C-a
Places the cursor at the beginning of a line
C-e
Places the cursor at the end of a line
C-f
Moves the cursor forward one character
C-b
Moves the cursor backward one character

Esc-f, Esc f, C-[ f

Moves the cursor forward one word

Esc-b, Esc b, C-[ b

Moves the cursor backward one word

Windows version /etc/services

%systemroot%\system32\drivers\etc\services

strncpy and null termination

strncpy does not put \n if the length fits its destination array. Needs to assure the string is null terminated in some way.

Ref:
http://www.thinkage.ca/english/gcos/expl/c/lib/strncp.html

Link: HTML5 Input Code Snippets

http://html5pattern.com/

Note: Don't trust what the user sent, and validate the input at the server side AGAIN. The client side process should be for reducing the response time. It's pretty easy to send arbitrary input value with an application such as WebScarab.

HTML and CSS Validator

HTML
http://validator.w3.org/#validate_by_upload

CSS
http://jigsaw.w3.org/css-validator/#validate_by_upload

GNS3: GNS3 does not allow IOS reload command

Need to use reload in GNS3 instead.