5. Communication between browsers and Squid

Most web browsers available today support proxying and are easily configured to use a Squid server as a proxy. Some browsers support advanced features such as lists of domains or URL patterns that shouldn't be fetched through the proxy, or JavaScript automatic proxy configuration.

5.1 Netscape manual configuration

Select Network Preferences from the Options menu. On the Proxies page, click the radio button next to Manual Proxy Configuration and then click on the View button. For each protocol that your Squid server supports (by default, HTTP, FTP, and gopher) enter the Squid server's hostname or IP address and put the HTTP port number for the Squid server (by default, 3128) in the Port column. For any protocols that your Squid does not support, leave the fields blank.

Here is a screen shot of the Netscape Navigator manual proxy configuration screen.

5.2 Netscape automatic configuration

Netscape Navigator's proxy configuration can be automated with JavaScript (for Navigator versions 2.0 or higher). Select Network Preferences from the Options menu. On the Proxies page, click the radio button next to Automatic Proxy Configuration and then fill in the URL for your JavaScript proxy configuration file in the text box. The box is too small, but the text will scroll to the right as you go.

Here is a screen shot of the Netscape Navigator automatic proxy configuration screen.

You may also wish to consult Netscape's documentation for the Navigator JavaScript proxy configuration

Here is a sample auto configuration JavaScript from Oskar Pearson:

//We (www.is.co.za) run a central cache for our customers that they
//access through a firewall - thus if they want to connect to their intranet
//system (or anything in their domain at all) they have to connect
//directly - hence all the "fiddling" to see if they are trying to connect
//to their local domain.

//Replace each occurrence of company.com with your domain name
//and if you have some kind of intranet system, make sure
//that you put it's name in place of "internal" below.

//We also assume that your cache is called "cache.company.com", and
//that it runs on port 8080. Change it down at the bottom.

//(C) Oskar Pearson and the Internet Solution (http://www.is.co.za)

    function FindProxyForURL(url, host)
        {
            //If they have only specified a hostname, go directly.
            if (isPlainHostName(host))
                    return "DIRECT";

            //These connect directly if the machine they are trying to
            //connect to starts with "intranet" - ie http://intranet
            //Connect  directly if it is intranet.*{
***************
*** 404,411 ****
                cp += n;                        /* name */
                type = ns_get16(cp);
                cp += INT16SZ;                  /* type */
!               class = ns_get16(cp);
!               cp += INT16SZ + INT32SZ;        /* class, TTL */
                n = ns_get16(cp);
                cp += INT16SZ;                  /* len */
                if (class != C_IN) {
--- 406,416 ----
                cp += n;                        /* name */
                type = ns_get16(cp);
                cp += INT16SZ;                  /* type */
!               class = _getshort(cp);
!               cp += INT16SZ;                  /* class */
!               if (qtype == T_A  && type == T_A)
!                       _dns_ttl_ = _getlong(cp);
!               cp += INT32SZ;                  /* TTL */
                n = ns_get16(cp);
                cp += INT16SZ;                  /* len */
                if (class != C_IN) {

2.10 My platform is BSD/OS or BSDI and I can't compile Squid

        cache_cf.c: In function `parseConfigFile':
        cache_cf.c:1353: yacc stack overflow before `token'
        ...

You may need to upgrade your gcc installation to a more recent version. Check your gcc version with

        gcc -v

2.11 Problems compiling libmiscutil.a on Solaris

The following error occurs on Solaris systems using gcc when the Solaris C compiler is not installed:

        /usr/bin/rm -f libmiscutil.a
        /usr/bin/false r libmiscutil.a rfc1123.o rfc1738.o util.o ...
        make[1]: *** [libmiscutil.a] Error 255
        make[1]: Leaving directory `/tmp/squid-1.1.11/lib'
        make: *** [all] Error 1

To fix this you either need to:

• Add /usr/ccs/bin to your PATH. This is where the ar command should be. You need to install SUNWbtool if ar is not there. Otherwise,
• Install the binutils package from the GNU FTP site. This package includes programs such as ar, as, and ld.

2.12 I have problems compiling Squid on Platform Foo.

Please check the page of platforms on which Squid is known to compile. Your problem might be listed there together with a solution. If it isn't listed there, mail us what you are trying, your Squid version, and the problems you encounter.

2.13 I see a lot warnings while compiling Squid.

Warnings are usually not a big concern, and can be common with software designed to operate on multiple platforms. If you feel like fixing compile-time warnings, please do so and send us the patches.

2.14 Building Squid on OS/2

by Doug Nazar

In order in compile squid, you need to have a reasonable facsimile of a Unix system installed. This includes bash, make, sed, emx, various file utilities and a few more. I've setup a TVFS drive that matches a Unix file system but this probably isn't strictly necessary.

I made a few modifications to the pristine EMX 0.9d install.

1. added defines for strcasecmp() & strncasecmp() to string.h
2. changed all occurrences of time_t to signed long instead of unsigned long
3. hacked ld.exe
   1. to search for both xxxx.a and libxxxx.a
   2. to produce the correct filename when using the -Zexe option

You will need to run scripts/convert.configure.to.os2 (in the Squid source distribution) to modify the configure script so that it can search for the various programs.

Next, you need to set a few environment variables (see EMX docs for meaning):

        export EMXOPT="-h256 -c"
        export LDFLAGS="-Zexe -Zbin -s"

Now you are ready to configure squid:

        ./configure

Compile everything:

        make

and finally, install:

        make install

This will by default, install into /usr/local/squid. If you wish to install somewhere else, see the --prefix option for configure.

Now, don't forget to set EMXOPT before running squid each time. I recommend using the -Y and -N options.

2.15 Building Squid on Cygwin

In order to compile squid, you need to have Cygwin fully installed.

Unpack the source archive as usual and run configure:

        ./configure

Compile everything:

        make

and finally, install:

        make install

This will by default, install into /usr/local/squid. If you wish to install somewhere else, see the --prefix option for configure.

Now, add a new Cygwin user - see the Cygwin user guide - and map it to SYSTEM, or create a new NT user, and a matching Cygwin user and they become the squid runas users.

Read the squid FAQ on permissions if you are using CYGWIN=ntsec.

After run squid -z. If that succeeds, try squid -N -D -d1, squid should start. Check that there are no errors. If everything looks good, try browsing through squid.

Now, configure cygrunsrv to run squid as a service as the chosen usercode. You may need to check permissions here.

//We (www.is.co.za) run a central cache for our customers that they
//access through a firewall - thus if they want to connect to their intranet
//system (or anything in their domain at all) they have to connect
//directly - hence all the "fiddling" to see if they are trying to connect
//to their local domain.

//Replace each occurrence of company.com with your domain name
//and if you have some kind of intranet system, make sure
//that you put it's name in place of "internal" below.

//We also assume that your cache is called "cache.company.com", and
//that it runs on port 8080. Change it down at the bottom.

//(C) Oskar Pearson and the Internet Solution (http://www.is.co.za)

    function FindProxyForURL(url, host)
        {
            //If they have only specified a hostname, go directly.
            if (isPlainHostName(host))
                    return "DIRECT";

            //These connect directly if the machine they are trying to
            //connect to starts with "intranet" - ie http://intranet
            //Connect  directly if it is intranet.*{
***************
*** 404,411 ****
                cp += n;                        /* name */
                type = ns_get16(cp);
                cp += INT16SZ;                  /* type */
!               class = ns_get16(cp);
!               cp += INT16SZ + INT32SZ;        /* class, TTL */
                n = ns_get16(cp);
                cp += INT16SZ;                  /* len */
                if (class != C_IN) {
--- 406,416 ----
                cp += n;                        /* name */
                type = ns_get16(cp);
                cp += INT16SZ;                  /* type */
!               class = _getshort(cp);
!               cp += INT16SZ;                  /* class */
!               if (qtype == T_A  && type == T_A)
!                       _dns_ttl_ = _getlong(cp);
!               cp += INT32SZ;                  /* TTL */
                n = ns_get16(cp);
                cp += INT16SZ;                  /* len */
                if (class != C_IN) {

        cache_cf.c: In function `parseConfigFile':
        cache_cf.c:1353: yacc stack overflow before `token'
        ...

        gcc -v