In this article, we setup squid proxy with ICAP. We will be configuring squid to enable SSL , ICAP (echo mode) & use squid to filter requests based on file type.
Prerequisites
Download the sources and copy them to your server.
$ sudo scp /dir/to/dowloaded/source linux@remote-server:/home/
In your server, run the following commands:
$ tar xzf squid-5.2.tar.gz $ cd squid-5.2/
Configure Squid Proxy
Compile your squid source to enable SSL and ICAP
$ ./configure --prefix=/usr --localstatedir=/var --libexecdir=${prefix}/lib/squid --datadir=${prefix}/share/squid --sysconfdir=/etc/squid --with-default-user=proxy --with-logdir=/var/log --with-pidfile=/var/run/squid.pid --with-default-user=proxy --with-openssl --enable-ssl-crtd --enable-icap-client --enable-ltdl-convenience $ sudo make $ sudo make install
Configure permissions
$ sudo chown -R proxy:proxy /usr/local/squid -R
Start squid
$ sudo /usr/local/squid/sbin/squid
Note: after every modification in squid.conf file in order to apply the changes you should reconfigure squid, you can find how to reconfigure it at the end of this article
SSL Configuration In Squid [Reference]
Create directory for SSL certificates and change permissions
$ sudo mkdir /usr/local/squid/etc/ssl_cert -p $ sudo chown proxy:proxy /usr/local/squid/etc/ssl_cert -R $ sudo chmod 700 /usr/local/squid/etc/ssl_cert -R
Change directory and create a self-signed SSL certificate.
$ cd /usr/local/squid/etc/ssl_cert $ sudo openssl req -new -newkey rsa:2048 -days <certificate validity period in days> -nodes -x509 -keyout squidCA.pem -out squidCA.pem
Create a trusted certificate to be imported into a browser.
$ sudo openssl x509 -in squidCA.pem -outform DER -out squid.der
Create a folder for future certificates.
$ sudo /usr/local/squid/libexec/security_file_certgen -c -s /usr/local/squid/var/cache/squid/ssl_db -M 4MB $ sudo chown -R proxy:proxy /usr/local/squid/var/cache/squid
Add these lines to squid.conf file
$ sudo vi /usr/local/squid/etc/squid.conf
http_port 3128 ssl-bump cert=/usr/local/squid/etc/ssl_cert/squidCA.pem generate-host-certificates=on dynamic_cert_mem_cache_size=8MB sslcrtd_program /usr/local/squid/libexec/security_file_certgen -s /usr/local/squid/var/cache/squid/ssl_db -M 4MB acl step1 at_step SslBump1 ssl_bump peek step1 ssl_bump bump all sslproxy_cert_error deny all
ICAP Configuration in Squid
Compile your ICAP source
$ sudo tar xvzf c_icap-0.5.10.tar.gz $ cd c_icap-0.5.10/ $ sudo make $ sudo make install
Test your ICAP setup with ICAP Client
$ sudo /usr/local/c-icap/bin/c-icap -N -D -d 10 $ sudo /usr/local/c-icap/bin/c-icap-client
You should get:
ICAP server:localhost, ip:127.0.0.1, port:1344 OPTIONS: Allow 204: Yes Allow 206: No Preview: 1024 Keep alive: Yes ICAP HEADERS: ICAP/1.0 200 OK Methods: RESPMOD, REQMOD Service: C-ICAP/0.5.10 server - Echo demo service ISTag: "CI0001-XXXXXXXXX" Transfer-Preview: * Options-TTL: 3600 Date: Sun, 12 Dec 2021 13:47:01 GMT Preview: 1024 Allow: 204 X-Include: X-Authenticated-User, X-Authenticated-Groups Encapsulated: null-body=0
Add these lines to squid.conf file
icap_enable on adaptation_send_username on adaptation_send_client_ip on icap_service srv_resp respmod_precache 0 icap://127.0.0.1:1344/echo #icap_service srv_req reqmod_precache 0 icap://localhost:1344/echo adaptation_access srv_resp allow all #adaptation_access srv_req allow all icap_service_failure_limit -1 icap_preview_enable off
Filter Requests based on file type/extension
In this example, we use squid to filter upload and download to the ICAP based on whether the file type is PDF.
edit rule_name and content/type and add these lines to squid.conf file
for request mode
acl rule_name req_mime_type -i content/type http_access allow|deny rule_name
example:
acl pdf_upload req_mime_type -i application/pdf http_access allow pdf_upload
for response mode
acl rule_name rep_mime_type -i content/type http_reply_acces allow rule_name
example:
acl pdf_download rep_mime_type -i application/pdf http_access allow pdf_download
Content of squid.conf
acl localnet src 0.0.0.1-0.255.255.255 # RFC 1122 "this" network (LAN) acl localnet src 10.0.0.0/8 # RFC 1918 local private network (LAN) acl localnet src 100.64.0.0/10 # RFC 6598 shared address space (CGN) acl localnet src 169.254.0.0/16 # RFC 3927 link-local (directly plugged) machines acl localnet src 172.16.0.0/12 # RFC 1918 local private network (LAN) acl localnet src 192.168.0.0/16 # RFC 1918 local private network (LAN) acl localnet src fc00::/7 # RFC 4193 local private network range acl localnet src fe80::/10 # RFC 4291 link-local (directly plugged) machines acl SSL_ports port 443 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 CONNECT method CONNECT acl pdf_upload req_mime_type -i application/pdf acl pdf_download rep_mime_type -i application/pdf http_access allow pdf_upload http_access allow pdf_download http_access deny !Safe_ports http_access deny CONNECT !SSL_ports http_access allow localhost manager http_access deny manager # ICAP Configuration icap_enable on adaptation_send_username on adaptation_send_client_ip on icap_service srv_resp respmod_precache 0 icap://127.0.0.1:1344/echo icap_service srv_req reqmod_precache 0 icap://127.0.0.1:1344/echo adaptation_access srv_resp allow pdf_download adaptation_access srv_req allow pdf_upload #adaptation_access srv_req allow all icap_service_failure_limit -1 http_access allow localhost http_access allow localnet http_access deny all #http_port 3128 http_port 3128 ssl-bump cert=/usr/local/squid/etc/squidCA.pem generate-host-certificates=on dynamic_cert_mem_cache_size=8MB sslcrtd_program /usr/local/squid/libexec/security_file_certgen -s /usr/local/squid/var/cache/squid/ssl_db -M 4MB acl step1 at_step SslBump1 ssl_bump peek step1 ssl_bump bump all sslproxy_cert_error deny all coredump_dir /var/spool/squid refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 refresh_pattern \/(Packages|Sources)(|\.bz2|\.gz|\.xz)$ 0 0% 0 refresh-ims refresh_pattern \/Release(|\.gpg)$ 0 0% 0 refresh-ims refresh_pattern \/InRelease$ 0 0% 0 refresh-ims refresh_pattern \/(Translation-.*)(|\.bz2|\.gz|\.xz)$ 0 0% 0 refresh-ims refresh_pattern . 0 20% 4320 cache_mem 512 MB
Reconfigure Squid.conf
$ sudo /usr/local/squid/sbin/squid -k reconfigure
References