I have been looking into this for a while after seeing conflicting answers to how SO_BINDTODEVICE is actually used. Some sources claim that the correct usage is to pass in a struct ifreq pointer, which has the device name and index obtained via an ioctl. For example: struct ifreq ifr; memset(&ifr, 0, sizeof(struct ifreq)); snprintf(ifr.ifr_name, … Read more
UDP is a perfectly viable protocol. It is the same old case of the right tool for the right job! If you have a program that waits for UDP datagrams, and then goes off to process them before returning to wait for another, then your elapsed processing time needs to always be faster than the … Read more
If i understand correctly, you are trying to communicate peer-to-peer between 2 clients each behind a different NAT, using a mediation server for hole punching? Few years ago i did the exact same thing in c#, i haven’t found the code yet, but ill give you some pointers if you like: First, I wouldn’t use … Read more
Yes, you can use the same port number for both TCP and UDP. Many protocols already do this, for example DNS works on udp/53 and tcp/53. Technically the port pools for each protocol are completely independent, but for higher level protocols that can use either TCP or UDP it’s convention that they default to the … Read more
You do it with the setsockopt() call, by using the IP_DONTFRAG option: int val = 1; setsockopt(sd, IPPROTO_IP, IP_DONTFRAG, &val, sizeof(val)); Here’s a page explaining this in further detail. For Linux, it appears you have to use the IP_MTU_DISCOVER option with the value IP_PMTUDISC_DO (or IP_PMTUDISC_DONT to turn it off): int val = IP_PMTUDISC_DO; setsockopt(sd, … Read more
TCP: Size of Ethernet frame – 24 Bytes Size of IPv4 Header (without any options) – 20 bytes Size of TCP Header (without any options) – 20 Bytes Total size of an Ethernet Frame carrying an IP Packet with an empty TCP Segment – 24 + 20 + 20 = 64 bytes UDP: Size of … Read more
From RFC 2616: HTTP communication usually takes place over TCP/IP connections. The default port is TCP 80, but other ports can be used. This does not preclude HTTP from being implemented on top of any other protocol on the Internet, or on other networks. HTTP only presumes a reliable transport; any protocol that provides such … Read more
This is one of my favorite questions. UDP is so misunderstood. In situations where you really want to get a simple answer to another server quickly, UDP works best. In general, you want the answer to be in one response packet, and you are prepared to implement your own protocol for reliability or to resend. … Read more
First of all, you should consider broadcast obsolete, specially INADDR_BROADCAST (255.255.255.255). Your question highlights exactly one of the reasons that broadcast is unsuitable. It should die along with IPv4 (hopefully). Note that IPv6 doesn’t even have a concept of broadcast (multicast is used, instead). INADDR_BROADCAST is limited to the local link. Nowadays, it’s only visible … Read more
You can’t send a UDP packet directly with WebRTC. That would violate the basic security constraints required by the browser. You can send SRTP to an ICE-enabled host. That is probably not what you are looking for. If a browser permitted sending arbitrary UDP packets, then malicious applications could send packets to any host. This … Read more