Ubuntu Feisty 7.04 manual page repository
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ipsvd(8) instructions directory ipsvd(7), can be told to read and follow instructions from a directory on incoming connections to the socket they listen on. For mostly static instructions or for performance reasons, it is possi‐ ble to compile the instructions from a directory into a constant ipsvd-cdb(8) for faster lookup, and to tell ipsvd(7) to read the instructions from there. ipsvd(7) matches the client’s IP address against files in the instructions directory. For example, the IP address a.b.c.d which reverse resolves to moa.bit.smarden.org is matched against the following files in the instructions directory, in this order, first match wins: 1. a.b.c.d 2. a.b.c 3. a.b 4. a If the client’s hostname has been successfully looked up in DNS: 5. moa.bit.smarden.org 6. bit.smarden.org 7. smarden.org 8. org And finally the catchall file ‘‘0’’ (zero): 9. 0 After successfully matching a client’s IP address or hostname against ipsvd(7) examines the file that matched the IP address or hostname, and acts accordingly: 1. If neither the user’s read permission, nor the user’s execute permission is set for the file, the connection is closed immedi‐ ately. ipsvd(7) reads the contents of the file and runs /bin/sh -c ’<contents>’ instead of the default program prog given at the command line for this connection. ipsvd(7) reads the contents of the file and interprets each line as an instruc‐ tion for this connection (see below). If the client’s IP address or hostname doesn’t match any file in the instructions directory, the default action is taken (the program prog is run to handle the connection). ipsvd(7) is given instructions for an incoming connection, it reads the corresponding file and interprets each line as follows. The file may be empty, meaning that there is no special instruction. +VAR=VALUE environment. If the line starts with a plus (‘‘+’’), and the ipsvd(7) puts the string following the plus into the environment before starting prog to handle the connection. If the string following the plus ipsvd(7) makes sure that the environ‐ ment variable with the name string is not set. Cnum[:msg] concurrency. If the line starts with a ‘‘C’’, and is followed by a number, the per host concurrency limit for the IP address that initiated the connection is set to this number. If num is zero, per host concurrency limit is disabled. If num is fol‐ lowed by ‘‘:msg’’, the message msg is written to this client if possible, if the per host concurrency limit is reached. msg may contain backslash-escaped characters as follows: ‘‘\\’’ is converted to a single backslash, ‘‘\n’’ is converted to a new line character, and ‘‘\r’’ is converted to a carriage return. On multiple concurrency instructions the last processed concur‐ ipsvd(7)’s support per host concurrency. =hostname[:forward] check hostname. If the line starts with a ‘‘=’’, and is fol‐ ipsvd(7) looks up the IP addresses for hostname in DNS and checks if the client’s IP address matches ipsvd(7) stops processing the instructions here and runs prog. If hostname is followed a ipsvd(7) now examines the file forward and acts accordingly, instead of running prog. All check hostname instructions in forward are ignored. If forward does not exist, the connection is closed. hostname may be ‘‘0’’ (zero), matching any IP address. Note: Using check hostname instructions can cause significant delay while responding to connection attempts, caused by DNS lookups. ipsvd(7) cannot interpret a line, it prints a warning, discards the line, and continues with the next instruction if any. ipsvd(7) runs prog. If the file contains at least one check hostname instruction, and none was success‐ ful, it closes the connection instead of running prog. +MEMORY=20000 This instruction causes the environment variable ‘‘MEMORY’’ with the value ‘‘20000’’ to be available to the program prog that handles the connection. +DEBUG= This instruction adds the variable ‘‘DEBUG’’ with an empty value to the environment. +LOGNAME This instructions makes sure that the environment variable ‘‘LOGNAME’’ is unset when running prog. C16 Set the per host concurrency to 16. A connection will be closed silently if there are already 16 active connections from this client’s IP address. =floyd.dyn.smarden.org:127.0.0.1 Check IP address of the dynamic hostname floyd.dyn.smarden.org. If one of the IP addresses floyd.dyn.smarden.org currently resolves to matches the client’s IP address, handle the connec‐ tion through the file 127.0.0.1 in the instructions directory. sslio(8) http://smarden.org/ipsvd/
Gerrit Pape <firstname.lastname@example.org> ipsvd-instruct(5)