c-ip being the IP address I want to extract

Since you haven't put this actual address in, it cannot be searched for in the sample data. But that's OK because really you just want whatever is in its place, so this will suffice:

#!/usr/bin/env perl 
use strict;
use warnings;

while (<DATA>) {
    my ($ip) = (/ 443 - (.+) curl/);
    print "Line $.: Found $ip\n";
}

__DATA__
2017-12-08 07:01:39 <s-ip> GET /course-detail.aspx id=66&catColor=0 44
+3 - <c-ip> curl/7.19.7+(x86_64-redhat-linux-gnu)+libcurl/7.19.7+NSS/3
+.27.1+zlib/1.2.3+libidn/1.18+libssh2/1.4.2 200 0 0 530
2017-12-08 07:01:39 <s-ip> GET /course-listing.aspx - 443 - <c-ip> cur
+l/7.19.7+(x86_64-redhat-linux-gnu)+libcurl/7.19.7+NSS/3.27.1+zlib/1.2
+.3+libidn/1.18+libssh2/1.4.2 200 0 0 140
2017-12-08 07:01:39 <s-ip> GET /course-detail.aspx id=24&catColor=0 44
+3 - <c-ip> curl/7.19.7+(x86_64-redhat-linux-gnu)+libcurl/7.19.7+NSS/3
+.27.1+zlib/1.2.3+libidn/1.18+libssh2/1.4.2 200 0 0 93
2017-12-08 07:01:40 <s-ip> GET /logistics.aspx - 443 - <c-ip> curl/7.1
+9.7+(x86_64-redhat-linux-gnu)+libcurl/7.19.7+NSS/3.27.1+zlib/1.2.3+li
+bidn/1.18+libssh2/1.4.2 200 0 0 46
2017-12-08 07:01:40 <s-ip> GET /course-detail.aspx id=23&catColor=0 44
+3 - <c-ip> curl/7.19.7+(x86_64-redhat-linux-gnu)+libcurl/7.19.7+NSS/3
+.27.1+zlib/1.2.3+libidn/1.18+libssh2/1.4.2 200 0 0 140
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