SQUID Frequently Asked Questions: Troubleshooting

11. Troubleshooting

11.1 Why am I getting ``Proxy Access Denied?''

If squid is in httpd-accelerator mode, it will accept normal HTTP requests and forward them to a HTTP server, but it will not honor proxy requests. If you want your cache to also accept proxy-HTTP requests then you must enable this feature:

        http_accel_with_proxy on

Alternately, you may have misconfigured one of your ACLs. Check the access.log and squid.conf files for clues.

11.2 I can't get `local_domain` to work; Squid is caching the objects from my local servers.

The local_domain directive does not prevent local objects from being cached. It prevents the use of sibling caches when fetching local objects. If you want to prevent objects from being cached, use the cache_stoplist or http_stop configuration options (depending on your version).

11.3 I get `Connection Refused` when the cache tries to retrieve an object located on a sibling, even though the sibling thinks it delivered the object to my cache.

If the HTTP port number is wrong but the ICP port is correct you will send ICP queries correctly and the ICP replies will fool your cache into thinking the configuration is correct but large objects will fail since you don't have the correct HTTP port for the sibling in your squid.conf file. If your sibling changed their http_port, you could have this problem for some time before noticing.

11.4 Running out of filedescriptors

If you see the Too many open files error message, you are most likely running out of file descriptors. This may be due to running Squid on an operating system with a low filedescriptor limit. This limit is often configurable in the kernel or with other system tuning tools. There are two ways to run out of file descriptors: first, you can hit the per-process limit on file descriptors. Second, you can hit the system limit on total file descriptors for all processes.

Linux

Have a look at filehandle.patch by Michael O'Reilly

If your kernel version is 2.2.x or greater, you can read and write the maximum number of file handles and/or inodes simply by accessing the special files:

        /proc/sys/fs/file-max
        /proc/sys/fs/inode-max

So, to increase your file descriptor limit:

        echo 3072 > /proc/sys/fs/file-max

If your kernel version is between 2.0.35 and 2.1.x (?), you can read and write the maximum number of file handles and/or inodes simply by accessing the special files:

        /proc/sys/kernel/file-max
        /proc/sys/kernel/inode-max

While this does increase the current number of file descriptors, Squid's configure script probably won't figure out the new value unless you also update the include files, specifically the value of OPEN_MAX in /usr/include/linux/limits.h.

Solaris

Add the following to your /etc/system file to increase your maximum file descriptors per process:

        set rlim_fd_max = 4096
        set rlim_fd_cur = 1024

You should also #define SQUID_FD_SETSIZE in include/config.h to whatever you set rlim_fd_max to. Going beyond 4096 may break things in the kernel.

Solaris' select(2) only handles 1024 descriptors, so if you need more, edit src/Makefile and enable $(USE_POLL_OPT). Then recompile squid. (version 1.1 only, version 2 automaticallyk things in the kernel.