Hey folks, I'm trying to finish an iRule and I'd appreciate some critiquing or advice. I'm trying to capture some client IP/SSL cipher information as well as a 23 character string of text that will be divided up into two identifiers. I think the two log statements (Client Accept and Client handshake) are redundant and can go away I have a regular expression line after the scan command. I have verified that the regex line actually works, but I'm not confident about the scan commmand. All I know is that regex is really looked down upon. Variables. Ugh. I'm learning TCL. I left the three main variables "empty" then I have the log command fill them out. I believe this is the right way, but I'm probably wrong. when CLIENT_ACCEPTED { log local0. "SSL_CUSTOM: Connection of Client Source IP: [IP::client_addr]:[TCP::client_port]<-->[virtual name]<-->[LB::server]" } when CLIENTSSL_HANDSHAKE { if { [SSL::cipher bits] > 0 } then { log local0. "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]." SSL::collect } } when CLIENTSSL_DATA { set combo "" set tid "" set mid "" set combo [scan [SSL::payload] ([0-9]{8}[0-9]{15}){1}] set tid [string range $combo 0 7] set mid [string range $combo 8 end] log local0. "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]. MID is $mid. TID is $TID." SSL::release }

Ok, we are closer guys. Thanks so far. This is not an HTTPS transaction according to the application group I'm working with scan [SSL::payload] {[0-9]{8}[0-9]{15}){1}} combo Does scan perform the same search action as a regex? I've attached a screenshot of a log capture I ran on the LTM. If I run a regex against a log file, It does capture the 23 characters properly.

Scan command and variables in a SSL transaction

11 Replies

nitass

Employee

Dec 27, 2017

I'm trying to capture some client IP/SSL cipher information as well as a 23 character string of text that will be divided up into two identifiers.

are the 23 chars in http request? if yes, isn't it easier to just use http_request event? ssl::payload is http request.

e.g.

// config

root@(ve13a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm virtual bar
ltm virtual bar {
    destination 172.28.24.10:443
    ip-protocol tcp
    mask 255.255.255.255
    pool foo
    profiles {
        clientssl {
            context clientside
        }
        tcp { }
    }
    rules {
        qux
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    translate-address enabled
    translate-port enabled
    vs-index 4
}
root@(ve13a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm rule qux
ltm rule qux {
when CLIENT_ACCEPTED {
  log local0. "SSL_CUSTOM: Connection of Client Source IP: [IP::client_addr]:[TCP::client_port]<-->[virtual name]<-->[LB::server]"
}
when CLIENTSSL_HANDSHAKE {
  if { [SSL::cipher bits] > 0 } then {
    log local0. "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]."
    SSL::collect
  }
}
when CLIENTSSL_DATA {
  log local0. [SSL::payload]
  SSL::release
}
}

// client

 curl -ik https://172.28.24.10
HTTP/1.1 200 OK
Date: Wed, 27 Dec 2017 01:06:34 GMT
Server: Apache/2.2.3 (CentOS)
Last-Modified: Fri, 15 Apr 2016 03:55:49 GMT
ETag: "418e44-6a-fc825b40"
Accept-Ranges: bytes
Content-Length: 106
Content-Type: text/html; charset=UTF-8






This is 101 host.




// log

[root@ve13a:Active:In Sync] config  tail -f /var/log/ltm
Dec 27 08:56:49 ve13a info tmm[17969]: Rule /Common/qux : SSL_CUSTOM: Connection of Client Source IP: 172.28.24.1:32806<-->/Common/bar<-->/Common/foo 0
Dec 27 08:56:49 ve13a info tmm[17969]: Rule /Common/qux : Client: 172.28.24.1 is using TLSv1.2. SSL Cipher:ECDHE-RSA-AES128-GCM-SHA256. Virtual:/Common/bar. SSL Profile:/Common/clientssl.
Dec 27 08:56:49 ve13a info tmm[17969]: Rule /Common/qux : GET / HTTP/1.1  User-Agent: curl/7.29.0  Host: 172.28.24.10  Accept: */*

by the way, scan command returns number of conversions performed (not string that matches a conversion specifier). in short, combo variable should be after the scan command.

e.g.

scan [SSL::payload] {[0-9]{8}[0-9]{15}){1}} combo

scan

https://www.tcl.tk/man/tcl/TclCmd/scan.htm

bongshanks
Nimbostratus
Dec 27, 2017
Ok, we are closer guys. Thanks so far. This is not an HTTPS transaction according to the application group I'm working with

scan [SSL::payload] {[0-9]{8}[0-9]{15}){1}} combo

Does scan perform the same search action as a regex?

I've attached a screenshot of a log capture I ran on the LTM. If I run a regex against a log file, It does capture the 23 characters properly.

nitass_89166

Noctilucent

Dec 27, 2017

I'm trying to capture some client IP/SSL cipher information as well as a 23 character string of text that will be divided up into two identifiers.

are the 23 chars in http request? if yes, isn't it easier to just use http_request event? ssl::payload is http request.

e.g.

// config

root@(ve13a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm virtual bar
ltm virtual bar {
    destination 172.28.24.10:443
    ip-protocol tcp
    mask 255.255.255.255
    pool foo
    profiles {
        clientssl {
            context clientside
        }
        tcp { }
    }
    rules {
        qux
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    translate-address enabled
    translate-port enabled
    vs-index 4
}
root@(ve13a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm rule qux
ltm rule qux {
when CLIENT_ACCEPTED {
  log local0. "SSL_CUSTOM: Connection of Client Source IP: [IP::client_addr]:[TCP::client_port]<-->[virtual name]<-->[LB::server]"
}
when CLIENTSSL_HANDSHAKE {
  if { [SSL::cipher bits] > 0 } then {
    log local0. "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]."
    SSL::collect
  }
}
when CLIENTSSL_DATA {
  log local0. [SSL::payload]
  SSL::release
}
}

// client

 curl -ik https://172.28.24.10
HTTP/1.1 200 OK
Date: Wed, 27 Dec 2017 01:06:34 GMT
Server: Apache/2.2.3 (CentOS)
Last-Modified: Fri, 15 Apr 2016 03:55:49 GMT
ETag: "418e44-6a-fc825b40"
Accept-Ranges: bytes
Content-Length: 106
Content-Type: text/html; charset=UTF-8






This is 101 host.




// log

[root@ve13a:Active:In Sync] config  tail -f /var/log/ltm
Dec 27 08:56:49 ve13a info tmm[17969]: Rule /Common/qux : SSL_CUSTOM: Connection of Client Source IP: 172.28.24.1:32806<-->/Common/bar<-->/Common/foo 0
Dec 27 08:56:49 ve13a info tmm[17969]: Rule /Common/qux : Client: 172.28.24.1 is using TLSv1.2. SSL Cipher:ECDHE-RSA-AES128-GCM-SHA256. Virtual:/Common/bar. SSL Profile:/Common/clientssl.
Dec 27 08:56:49 ve13a info tmm[17969]: Rule /Common/qux : GET / HTTP/1.1  User-Agent: curl/7.29.0  Host: 172.28.24.10  Accept: */*

by the way, scan command returns number of conversions performed (not string that matches a conversion specifier). in short, combo variable should be after the scan command.

e.g.

scan [SSL::payload] {[0-9]{8}[0-9]{15}){1}} combo

scan

https://www.tcl.tk/man/tcl/TclCmd/scan.htm

bongshanks
Nimbostratus
Dec 27, 2017
Ok, we are closer guys. Thanks so far. This is not an HTTPS transaction according to the application group I'm working with

scan [SSL::payload] {[0-9]{8}[0-9]{15}){1}} combo

Does scan perform the same search action as a regex?

I've attached a screenshot of a log capture I ran on the LTM. If I run a regex against a log file, It does capture the 23 characters properly.

nitass_89166

Noctilucent

Dec 27, 2017

Does scan perform the same search action as a regex?

can you try something like this?

// config

[root@ve13a:Active:In Sync] config  tmsh list ltm rule qux
ltm rule qux {
when CLIENT_ACCEPTED {
  log local0. "SSL_CUSTOM: Connection of Client Source IP: [IP::client_addr]:[TCP::client_port]<-->[virtual name]<-->[LB::server]"
}
when CLIENTSSL_HANDSHAKE {
  if { [SSL::cipher bits] > 0 } then {
    log local0. "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]."
    SSL::collect
  }
}
when CLIENTSSL_DATA {
  log local0. "\[SSL::payload\] is [SSL::payload]"
  if { [regexp {(\d{8})(\d{15})} [SSL::payload] -> tid mid] } {
    log local0. "tid=$tid mid=$mid"
  }
  SSL::release
}
}

// client

 (echo abc123xyz16021201334440212201602ijk987) |openssl s_client -connect 172.28.24.10:443 >& /dev/null

// log

[root@ve13a:Active:In Sync] config  tail -f /var/log/ltm
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : SSL_CUSTOM: Connection of Client Source IP: 172.28.24.1:32824<-->/Common/bar<-->/Common/foo 0
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : Client: 172.28.24.1 is using TLSv1.2. SSL Cipher:ECDHE-RSA-AES128-GCM-SHA256. Virtual:/Common/bar. SSL Profile:/Common/clientssl.
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : [SSL::payload] is abc123xyz16021201334440212201602ijk987
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : tid=16021201 mid=334440212201602

bongshanks

Nimbostratus

Dec 27, 2017

I'll try that in the next change window in a week

This is my first iteration that I wanted to try

when CLIENTSSL_DATA {
set payload [SSL::payload] 
set combo ""
set tid ""
set mid ""
regexp ([0-9]{8}[0-9]{15}){1} $payload combo 
set tid [string range $combo 0 7]
set mid [string range $combo 8 end]

nitass

Employee

Dec 27, 2017

Does scan perform the same search action as a regex?

can you try something like this?

// config

[root@ve13a:Active:In Sync] config  tmsh list ltm rule qux
ltm rule qux {
when CLIENT_ACCEPTED {
  log local0. "SSL_CUSTOM: Connection of Client Source IP: [IP::client_addr]:[TCP::client_port]<-->[virtual name]<-->[LB::server]"
}
when CLIENTSSL_HANDSHAKE {
  if { [SSL::cipher bits] > 0 } then {
    log local0. "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]."
    SSL::collect
  }
}
when CLIENTSSL_DATA {
  log local0. "\[SSL::payload\] is [SSL::payload]"
  if { [regexp {(\d{8})(\d{15})} [SSL::payload] -> tid mid] } {
    log local0. "tid=$tid mid=$mid"
  }
  SSL::release
}
}

// client

 (echo abc123xyz16021201334440212201602ijk987) |openssl s_client -connect 172.28.24.10:443 >& /dev/null

// log

[root@ve13a:Active:In Sync] config  tail -f /var/log/ltm
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : SSL_CUSTOM: Connection of Client Source IP: 172.28.24.1:32824<-->/Common/bar<-->/Common/foo 0
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : Client: 172.28.24.1 is using TLSv1.2. SSL Cipher:ECDHE-RSA-AES128-GCM-SHA256. Virtual:/Common/bar. SSL Profile:/Common/clientssl.
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : [SSL::payload] is abc123xyz16021201334440212201602ijk987
Dec 27 11:24:53 ve13a info tmm[17969]: Rule /Common/qux : tid=16021201 mid=334440212201602

bongshanks

Nimbostratus

Dec 27, 2017

I'll try that in the next change window in a week

This is my first iteration that I wanted to try

when CLIENTSSL_DATA {
set payload [SSL::payload] 
set combo ""
set tid ""
set mid ""
regexp ([0-9]{8}[0-9]{15}){1} $payload combo 
set tid [string range $combo 0 7]
set mid [string range $combo 8 end]

bongshanks
Nimbostratus
Jan 10, 2018
Nitass, that is a better way of doing it. I'm trying to clean it up a little, add HSL, set the logs to a few entries as possible, and add an else statement in case the transaction is missing the TID/MID.

How is this?

bongshanks

Nimbostratus

Jan 10, 2018

when CLIENT_ACCEPTED {
set hsl [HSL::open -proto UDP -pool hsl_syslog_pool]
}
when CLIENTSSL_HANDSHAKE {
SSL::collect
}
}
when CLIENTSSL_DATA {
if { [regexp {(\d{8})(\d{15})} [SSL::payload] -> tid mid] } {
HSL::send $hsl "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]. tid=$tid mid=$mid."
}
SSL::release
}
}  else {
 If we did not have a TID OR MID in the transaction then just log the info that we have                   
HSL::send $hsl "SSL_CUSTOM: No TID or MID TYPE found for Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]."
}
}

nitass

Employee

Jan 13, 2018

you mean this one, don't you? if yes, it looks okay to me.

when CLIENT_ACCEPTED {
  set hsl [HSL::open -proto UDP -pool hsl_syslog_pool]
}
when CLIENTSSL_HANDSHAKE {
  SSL::collect
}
when CLIENTSSL_DATA {
  if { [regexp {(\d{8})(\d{15})} [SSL::payload] -> tid mid] } {
    HSL::send $hsl "Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]. tid=$tid mid=$mid."
  } else {
     If we did not have a TID OR MID in the transaction then just log the info that we have                   
    HSL::send $hsl "SSL_CUSTOM: No TID or MID TYPE found for Client: [IP::client_addr] is using [SSL::cipher version]. SSL Cipher:[SSL::cipher name]. Virtual:[virtual]. SSL Profile:[PROFILE::clientssl name]."
  }
  SSL::release  
}

Forum Discussion

Scan command and variables in a SSL transaction

11 Replies

F5 Academy at AppWorld 2026

Introducing the F5 AI Assistant for BIG-IP

Recent Discussions

Connection Rest f5

Kubernetes cert-manager + LetsEncrypt + F5

The GSLB pool is providing an incorrect IP to end users

Unable to ping from some self ip on Velos

Not seeing the latest F5OS-A when running Journeys

Related Content

APM variable assign examples

WAF evasion techniques for Command Injection

Getting Started with iRules: Variables

Power of tmsh commands using Ansible

Lightboard Lessons: SSL Transactions Per Second

ABOUT DEVCENTRAL

RESOURCES

SUPPORT

PARTNERS