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("1.2.3.4/255.240.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/12");
    subnet = ResolveSubNet("1.2.3.4/255.224.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/11");
    subnet = ResolveSubNet("1.2.3.4/255.192.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/10");
    subnet = ResolveSubNet("1.2.3.4/255.128.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/9");
    subnet = ResolveSubNet("1.2.3.4/255.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1.0.0.0/8");
    subnet = ResolveSubNet("1.2.3.4/254.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/7");
    subnet = ResolveSubNet("1.2.3.4/252.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/6");
    subnet = ResolveSubNet("1.2.3.4/248.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/5");
    subnet = ResolveSubNet("1.2.3.4/240.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/4");
    subnet = ResolveSubNet("1.2.3.4/224.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/3");
    subnet = ResolveSubNet("1.2.3.4/192.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/2");
    subnet = ResolveSubNet("1.2.3.4/128.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/1");
    subnet = ResolveSubNet("1.2.3.4/0.0.0.0");
    BOOST_CHECK_EQUAL(subnet.ToString(), "0.0.0.0/0");
    subnet = ResolveSubNet("1:2:3:4:5:6:7:8/ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1:2:3:4:5:6:7:8/128");
    subnet = ResolveSubNet("1:2:3:4:5:6:7:8/ffff:0000:0000:0000:0000:0000:0000:0000");
    BOOST_CHECK_EQUAL(subnet.ToString(), "1::/16");