Intermediate iRules: High Speed Logging - Spray Those Log Statements!
High Speed Logging has been around since version 10.1, and has been integral to many projects over the past few years. Prior to HSL's introduction, logging remotely was configured entirely in syslog or could be handled in iRules by specifying a destination in the log statement. One enhancement with HSL to that scenario was to allow a pool of servers to be configured for a destination, so given a pool of servers, the log messages were sure to arrive somewhere (ok, for TCP they were sure to arrive!) A drawback with either the log or HSL::send command, however, is that the message was only going to hit one destination. A workaround for that problem is to just use as many commands as necessary to hit all your destinations, but that's not very efficient. Enter the publisher. Beginning in version 11.3, a new option to the HSL::open command was added that allows you to send data to a log publisher instead of only to a pool. This allows you to spray that data to as many servers as you like. In my test setup, I used alias interfaces on a linux virtual machine as the destinations, and created a pool for each to be added to the publisher: ltm pool lp1 { members { 192.168.101.20:514 { address 192.168.101.20 } } } ltm pool lp2 { members { 192.168.101.21:514 { address 192.168.101.21 } } } ltm pool lp3 { members { 192.168.101.22:514 { address 192.168.101.22 } } } Once I have the pools defined, I create the log destinations: sys log-config destination remote-high-speed-log lp1 { pool-name lp1 protocol udp } sys log-config destination remote-high-speed-log lp2 { pool-name lp2 protocol udp } sys log-config destination remote-high-speed-log lp3 { pool-name lp3 protocol udp } Finally, I create the publisher for use in the iRules: sys log-config publisher lpAll { destinations { lp1 lp2 lp3 } } That's all the background magic required to get to the iRules showing off the -publisher option in HSL::open: ltm rule testrule { when CLIENT_ACCEPTED { set lpAll [HSL::open -publisher /Common/lpAll] } when HTTP_REQUEST { HSL::send $lpAll "<190> [IP::client_addr]:[TCP::client_port]-[IP::local_addr]:[TCP::local_port]; [HTTP::host][HTTP::uri]" } } Finally, some visual evidence for the skeptics out there: You can see that all three destinations got the message, and the message arrived as formatted. So now, armed with this new option (as of version 11.3), go forth and code!
Log large HTTP payloads in chunks locally and remotely
Problem this snippet solves: Log HTTP POST request payloads remotely via High Speed Logging (HSL) to a syslog server and locally. Code : # Log POST request payloads remotely via HSL to a syslog server and locally. # Based on Steve Hillier's example and the HTTP::collect wiki page # https://devcentral.f5.com/s/wiki/iRules.http__collect.ashx # Note that although any size payload can theoretically be collected, the maximum size of a Tcl variable in v9 and v10 is 4MB # with a smaller functional maximum after charset expansion of approximately 1Mb. # In v11, the maximum variable size was increased to 32Mb. when RULE_INIT { # Log debug to /var/log/ltm? 1=yes, 0=no set static::payload_dbg 1 # Limit payload collection to 5Mb set static::max_collect_len 5242880 # HSL pool name set static::hsl_pool "my_hsl_tcp_pool" # Max characters to log locally (must be less than 1024 bytes) # https://devcentral.f5.com/s/wiki/iRules.log.ashx set static::max_chars 900 } when HTTP_REQUEST { # Only collect POST request payloads if {[HTTP::method] equals "POST"}{ if {$static::payload_dbg}{log local0. "POST request"} # Open HSL connection set hsl [HSL::open -proto TCP -pool $static::hsl_pool] # Get the content length so we can request the data to be processed in the HTTP_REQUEST_DATA event. if {[HTTP::header exists "Content-Length"]}{ set content_length [HTTP::header "Content-Length"] } else { set content_length 0 } # content_length of 0 indicates chunked data (of unknown size) if {$content_length > 0 && $content_length < $static::max_collect_len}{ set collect_length $content_length } else { set collect_length $static::max_collect_len } if {$static::payload_dbg}{log local0. "Content-Length: $content_length, Collect length: $collect_length"} } } when HTTP_REQUEST_DATA { # Log the bytes collected if {$static::payload_dbg}{log local0. "Collected [HTTP::payload length] bytes"} # Send all the collected payload to the remote syslog server HSL::send $hsl "<190>[HTTP::payload]\n" # Log the payload locally if {[HTTP::payload length] < $static::max_chars}{ log local0. "Payload=[HTTP::payload]" } else { # Initialize variables set remaining $payload set position 0 set count 1 set bytes_logged 0 # Loop through and log each chunk of the payload while {[string length $remaining] > $static::max_chars}{ # Get the current chunk to log (subtract 1 from the end as string range is 0 indexed) set current [string range $remaining $position [expr {$position + $static::max_chars -1}]] log local0. "chunk $count=$current" # Add the length of the current chunk to the position for the next chunk incr position [string length $current] # Get the next chunk to log set remaining [string range $remaining $position end] incr count incr bytes_logged $position log local0. "remaining bytes=[string length $remaining], \$position=$position, \$count=$count, \$bytes_logged=$bytes_logged" } if {[string length $remaining]}{ log local0. "chunk $count=$current" incr bytes_logged [string length $remaining] } log local0. "Logged $count chunks for a total of $bytes_logged bytes" } }
Device Fingerprinting for mobile devices
We have published Microsoft Exchange server behind ASM+APM policies. I am using BotDefense to generate Device IDs for the connecting clients and then inserting the value of "device_id" variable into HTTP header and then passing it to APM. APM extracts the "device_id" value from HTTP header and sets it as an APM variable: ACCESS::session data set "session.custom.device_id" "$device_id" This APM session variable is then called in APM iRules to perform the required logic. So far, the logic and traffic flow is working as expected. Now, here comes the problem part: If the client is not a web browser, the whole logic fails because BotDefense is generating Device IDs based on JavaScript challenge. In case of Microsoft Exchange, the client could be a mobile device using the native email app of the phone (not mobile browser) like the mail app of Andriod or iOS devices. How can we perform device fingerprinting and generate Device IDs in such case? All mobile devices use the standard Exchange protocol "Microsoft ActiveSync" which is based on HTTPS. When traffic hits my virtual server from a mobile client, BIG-IP can detect it and differentiate it from other web browser traffic because all requests coming from mobile devices have this particular URI string in the HTTP Request: "/Microsoft-Server-ActiveSync". But because it is not a web browser, the JavaScript challenge is not performed and no Device ID generated. My question is: How can we perform fingerprinting and generate Device IDs for mobile devices (not mobile browsers)? Here is my ASM iRule which is handling the Device IDs and fingerprinting: ============================================================================================================================== when RULE_INIT { set static::TPS_Value 1 set static::debug 1 # set as 1 - send request logs set 0 if no request logs should be sent. set static::PBD_debug 1 # list of botdefense actions you want to get request log on set static::Logged_PBD_actions "tcp_rst browser_challenge internal_bigip_response captcha_challenge" set static::host_header "Host: webmail.company.com" } when HTTP_REQUEST { set hsl [HSL::open -proto TCP -pool ASM_Log_Pool2] set http_request [HTTP::request] #HSL::send $hsl $http_request } when BOTDEFENSE_REQUEST { #for demo purpose, make the challange valid from the first request - make sure you go to the default if {[HTTP::uri] equals "/"} { BOTDEFENSE::cs_allowed true } #Mandate the device_id attribute extraction BOTDEFENSE::cs_attribute device_id enable } when BOTDEFENSE_ACTION { set device_id [BOTDEFENSE::device_id] if {$static::debug > 0} {log "reason is, [BOTDEFENSE::reason], action is [BOTDEFENSE::action], botdefense device_id is: $device_id"} if {$static::Logged_PBD_actions contains [BOTDEFENSE::action]} { set botdefense_action [BOTDEFENSE::action] set botdefense_reason [BOTDEFENSE::reason] set PBD_header [concat Host: webmail.company.com\r\nPbd_Action: $botdefense_action\r\nPbd_reason: $botdefense_reason] set asm_http_requet_log [string map -nocase [list $static::host_header $PBD_header] $http_request] if {($static::PBD_debug > 0) && ([info exists asm_http_requet_log])} { HSL::send $hsl $asm_http_requet_log } } log "action is [BOTDEFENSE::action], reason is: [BOTDEFENSE::reason] cs_allowed is: [BOTDEFENSE::cs_allowed]" if {([BOTDEFENSE::action] eq "tcp_rst") && [BOTDEFENSE::cs_allowed] eq 0} { set res [BOTDEFENSE::action custom_response { sorry i am blocking you, try to restart the session } 200] if {$res eq "ok"} { set botdefense_responded 1 } } #if {[BOTDEFENSE::action] eq "captcha_challenge"} { #set res [BOTDEFENSE::action allow] #log "captcha challange with res $res" #if {$res eq "ok"} { #log "bypass allow" #} #} #} when ASM_REQUEST_DONE { if {$static::debug > 0} {log "http uri is [HTTP::uri]"} virtual Hackazone_APM_virt } when HTTP_REQUEST_SEND { clientside { # Need to force the host header replacement and HTTP:: commands into the clientside context # as the HTTP_REQUEST_SEND event is in the serverside context if {$static::debug > 0} {log "device id is: $device_id"} HTTP::header insert "device_id" "$device_id" #if { $suspicious_browser eq "1" } { #HTTP::header insert "suspicious_browser" "1" #log "sending suspicious_browser header" #} #log "after the change [HTTP::request]" } } when HTTP_RESPONSE_RELEASE { if {[info exists botdefense_responded]} { HTTP::header insert "X-TS-BP-Action" "2" } } =================================================================================================================================== Many thanks.
