Регистрация с группы разрешенных сетей

через iptables. астериск вам не фаервол.

    IRATE=20/minute

    # REGISTER rate, per host.
    RRATE=10/minute

    # All other SIP methods rate, per host.  Be careful with SUBSCRIBEs, OPTIONS, CANCELs, etc.
    ORATE=60/minute

    # Methods for this script to ignore.  These SIP methods are always allowed.
    IGMETH="OPTIONS"

    # Burst
    BURST=30

    # Interface(s) to protect on INPUT. Seperate multiple interfaces with spaces.
    # This will protect SIP services on THIS HOST.
    IFACE="eth0"

# Search packet to this location. A larger offset looks further into the packet
# and takes more time but could catch more attacks (and false alarms).
# Remember, the method to match on is always in the beginning of the packet.
OFFSET=65

# тут чтото еще есть, много ;)

        $IPTABLES -A sipdos -m string --string "INVITE sip:" --algo bm --to $OFFSET -j sipdosinvite

        $IPTABLES -A sipdosinvite \
        -m hashlimit --hashlimit $IRATE --hashlimit-burst $BURST \
        --hashlimit-mode srcip,dstport --hashlimit-name sip_i_limit -j ACCEPT

        # REGISTER limit
        $IPTABLES -A sipdos -m string --string "REGISTER sip:" --algo bm --to $OFFSET -j sipdosregister

        $IPTABLES -A sipdosregister \
        -m hashlimit --hashlimit $RRATE --hashlimit-burst $BURST \
        --hashlimit-mode srcip,dstport --hashlimit-name sip_r_limit -j ACCEPT