On 2/24/22 10:03, Felipe Polanco wrote:
Does squid first complete the tcp handshake on its users and then a second handshake on the destination IP
Yes, kind of. Keep in mind that Squid pretty much does not know anything about TCP handshakes, SYN packets, etc. Nearly all TCP-level work is done by the kernel and system libraries. Squid uses TCP socket I/O.
Also, there may be no corresponding Squid-server connection at all (e.g., errors and cache hits) or, as Amos has already noted, multiple Squid-server connections (e.g., trying different IP addresses associated with the same DNS name in HTTP request target).
or as soon as it receives the TCP SYN flag it does the same with the destination.
No, Squid does not known anything about the SYN flag. Squid does not act on the incoming TCP connection until a successful accept(2) system call announces/gives that connection to Squid. That system call extracts an already established (i.e. post-handshake) TCP connection from the queue(s) of TCP connections maintained by the kernel. The TCP handshake completes before Squid gets control back from accept() and, in the vast majority of cases, before Squid even calls accept().
HTH, Alex. _______________________________________________ squid-users mailing list squid-users@lists.squid-cache.org http://lists.squid-cache.org/listinfo/squid-users
