Comment from Marco [here](https://github.com/bitcoin/bitcoin/pull/19954#discussion_r503075378):
> + make -C src --jobs=1 check-security V=1
make: Entering directory '/bitcoin/distsrc-x86_64-linux-gnu/src'
Checking binary security...
READELF=/gnu/store/pzq9s5ldl90h72p26jkdakyccdg9ib3k-profile/bin/x86_64-linux-gnu-readelf OBJDUMP=x86_64-linux-gnu-objdump OTOOL= /gnu/store/pzq9s5ldl90h72p26jkdakyccdg9ib3k-profile/bin/python3.7 ../contrib/devtools/security-check.py bitcoind  bitcoin-cli bitcoin-tx bitcoin-wallet test/test_bitcoin bench/bench_bitcoin qt/bitcoin-qt  
make: Leaving directory '/bitcoin/distsrc-x86_64-linux-gnu/src'
> + case "$HOST" in
> + make -C src --jobs=1 check-symbols V=1
make: Entering directory '/bitcoin/distsrc-x86_64-linux-gnu/src'
Checking glibc back compat...
READELF=/gnu/store/pzq9s5ldl90h72p26jkdakyccdg9ib3k-profile/bin/x86_64-linux-gnu-readelf CPPFILT=/gnu/store/pzq9s5ldl90h72p26jkdakyccdg9ib3k-profile/bin/x86_64-linux-gnu-c++filt /gnu/store/pzq9s5ldl90h72p26jkdakyccdg9ib3k-profile/bin/python3.7 ../contrib/devtools/symbol-check.py bitcoind  bitcoin-cli bitcoin-tx bitcoin-wallet test/test_bitcoin bench/bench_bitcoin qt/bitcoin-qt  
test/test_bitcoin: export of symbol in6addr_loopback not allowed
test/test_bitcoin: failed EXPORTED_SYMBOLS
make: *** [Makefile:20952: check-symbols] Error 1
make: Leaving directory '/bitcoin/distsrc-x86_64-linux-gnu/src'

**test/test_bitcoin: export of symbol in6addr_loopback not allowed**
subnet = ResolveSubNet("1.2.3.4/255.255.255.224");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.3.0/27");
    subnet = ResolveSubNet("1.2.3.4/255.255.255.192");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.3.0/26");
    subnet = ResolveSubNet("1.2.3.4/255.255.255.128");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.3.0/25");
    subnet = ResolveSubNet("1.2.3.4/255.255.255.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.3.0/24");
    subnet = ResolveSubNet("1.2.3.4/255.255.254.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.2.0/23");
    subnet = ResolveSubNet("1.2.3.4/255.255.252.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/22");
    subnet = ResolveSubNet("1.2.3.4/255.255.248.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/21");
    subnet = ResolveSubNet("1.2.3.4/255.255.240.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/20");
    subnet = ResolveSubNet("1.2.3.4/255.255.224.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/19");
    subnet = ResolveSubNet("1.2.3.4/255.255.192.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/18");
    subnet = ResolveSubNet("1.2.3.4/255.255.128.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/17");
    subnet = ResolveSubNet("1.2.3.4/255.255.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/16");
    subnet = ResolveSubNet("1.2.3.4/255.254.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.2.0.0/15");
    subnet = ResolveSubNet("1.2.3.4/255.252.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/14");
    subnet = ResolveSubNet("1.2.3.4/255.248.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/13");