s6-networking
Software
skarnet.org

The s6-tcpserver program

s6-tcpserver is an UCSPI tool for TCP connections, i.e. a super-server. It accepts connections from clients, and forks a program to handle each connection.

Interface

     s6-tcpserver [ -q | -Q | -v ] [ -4 | -6 ] [ -1 ] [ -c maxconn ] [ -C localmaxconn ] [ -b backlog ] [ -G gidlist ] [ -g gid ] [ -u uid ] [ -U ] ip port prog...

• s6-tcpserver executes into s6-tcpserver4 or s6-tcpserver6 depending on whether ip is an IPv4 or IPv6 address. It modifies some of its option syntax to match s6-tcpserver4 and s6-tcpserver6's.
• s6-tcpserver4 or s6-tcpserver6 handles the connection itself.

Options

• -q : be quiet. This is converted into -v 0 for s6-tcpserver4 or s6-tcpserver6.
• -Q : be normally quiet. This is converted into -v 1 for s6-tcpserver4 or s6-tcpserver6. This is the default.
• -v : be verbose. This is converted into -v 2 for s6-tcpserver4 or s6-tcpserver6.
• -4 : IPv4 only. Interpret ip as IPv4; if it is invalid, exit 100.
• -6 : IPv6 only. Interpret ip as IPv6; if it is invalid, exit 100. If neither the -4 nor the -6 option is given, s6-tcpserver will parse ip to determine its family.
• Every other option is passed verbatim to s6-tcpserver4 or s6-tcpserver6.

Notes

• s6-tcpserver executes either into s6-tcpserver4, which only serves IPv4, or into s6-tcpserver6, which only serves IPv6. It will not bind to every available IP address of the machine whether they are v4 or v6; on the other hand, it can bind to every available IPv4 address (if ip is 0.0.0.0) or to every available IPv6 address (if ip is ::). Two instances of s6-tcpserver can cover every available address.