The ucsd-psystem-fs package allows you to mount UCSD p-System filesystem disk images as Linux file systems. It is a implemented in user space, using the FUSE library and module. The ucsd-psystem-fs package also includes several other tools for manipulating UCSD p-System disk images.
ucspi-ipc implements D. J. Bernstein's UCSPI protocol in the Unix domain, making it trivial to set up clients or servers on Unix sockets. ucspi- ipc comes with utilities using credential passing on Unix sockets, which are designed to act like a fine-grained and efficient sudo without the need for setuid programs.
udhcp Server/Client is an embedded DHCP client and server that can be compiled seperately (19k and 17k respectively), or as one combined binary (29k). The server stores its lease file periodically, or by a signal (for systems with flash memory) in terms of absolute time of lease expiration, or time remaining in a lease (for systems with no clocks). The client calls helper scripts to do the work of configuring the interfaces for more flexibility. udhcp has been included in BusyBox and is no longer maintained as a separate project.
udp_copy2 consists of two executables, udp_send2 and udp_recv2, implementing plain text non-interactive data transfer over UDP/IPv4 with a preset transfer rate. On lossy links, it yields better throughput than TCP-based transfers. It may also be used for smooth user space throttling. It dedicates a mode to SNAT/MASQ so the receiver can initiate transfer from behind a firewall. It features a very precise user space packet scheduler. It handles SIGSTOP in a rational way. It only transfers in one direction for one invocation. It needs and uses no synchronous I/O multiplexing. Shell access is required on both ends. The package also contains the auxiliary multi-threaded tool "bigpipe", which can be used to reduce pipeline latency.
udpeq balances UDP traffic over parallel routes, useful if you want to connect two endpoints through several slow or unreliable channels. For example, if you have three modem lines and a one-way satellite link, you might want to bond all of these together to form a faster, more reliable "virtual" connection.