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JG's avatar
JG
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May 18, 2014

iRule for SMTP: Passing Client IP Addr to backend mail servers

When SNATs are used for a virtual server, the backend SMTP servers cannot get the client IP address. This irule is intended to replace the string after "EHLO" or "HELO" in mail client initiation with...
application delivery
deployment
devops
iRules
LTM
security
JG's avatar
JG
Icon for Cumulonimbus rankCumulonimbus
May 18, 2014

Thanks so much, John! Here's a new version of it based on your advice:

when CLIENT_ACCEPTED {
    set c-addr [IP::client_addr]
    log local0. "Client addr: $c-addr"
    STREAM::expression {@^EHLO.*\r\n@@ @^HELO.*\r\n@@}
    STREAM::enable
}

when STREAM_MATCHED {
    set mstring [STREAM::match]
    log local0. "STREAM_MATCHED: string: $mstring"
    set replacment [string range $mstring 0 1]
    append replacment "LO $c-addr\r\n"
    log local0. "STREAM_MATCHED: replacement string: $replacement"
    STREAM::replace "$mstring/$replacment"
    event STREAM_MATCHED disable
}

when SERVER_CONNECTED {
    STREAM::disable
}

I can't test this (it compiled alright) yet because my devices are all firewall'ed off at the moment.