我正在使用以下squid.conf
acl Safe_ports port 80 # http
acl Safe_ports port 21 # ftp
acl Safe_ports port 443 # https
acl Safe_ports port 70 # gopher
acl Safe_ports port 210 # wais
#acl Safe_ports port 1025-65535 # unregistered ports
acl Safe_ports port 280 # http-mgmt
acl Safe_ports port 488 # gss-http
acl Safe_ports port 591 # filemaker
acl Safe_ports port 777 # multiling http
acl Safe_ports port 9100 # printer
acl Safe_ports port 427 # udp port for printer
acl Safe_ports port 137 # udp port for printer
acl Safe_ports port 161 # udp port for printer
acl Safe_ports port 123 # udp port for NTP
acl Safe_ports port 2159 # udp port for gdb
acl CONNECT method CONNECT
acl whitelist dstdomain "/etc/squid/whitelist.txt"
#http_access deny !whitelist
#http_access deny !Safe_ports
#http_access deny CONNECT !SSL_ports
#acl IP_whitelist src 172.16.140.34
#http_access allow IP_whitelist
http_access allow localhost manager
http_access deny manager
http_access allow localhost
http_access deny all
http_port 3128
coredump_dir /var/spool/squid3
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern -i (/cgi-bin/|\?) 0 0% 0
refresh_pattern (Release|Packages(.gz)*)$ 0 20% 2880
refresh_pattern . 0 20% 4320
request_header_add X-Custom-Caller "Alfarhan-System-Image/1.1" all
include /etc/squid/conf.d/*.conf
该配置可在Ubuntu 16.04上使用，但是升级到Ubuntu 18.04后，我无法访问列入白名单的网站。
以下几行来自squid的访问日志：
1548355758.020 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355758.020 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355758.021 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355758.022 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355777.119 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355777.402 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355777.416 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355777.433 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355777.435 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355777.437 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
1548355787.873 0 127.0.0.1 TAG_NONE/503 0 CONNECT clients1.google.com:443 - HIER_NONE/- -
请在这里帮助我：（