PDA

Archiv verlassen und diese Seite im Standarddesign anzeigen : Mir unbekannt port Fehlermeldung



jockelb
11.11.02, 22:00
Tachjen,

ich habe ein Problem mit meinem mldonkey client. Es wird nicht mehr gesaugt. Was mir aufgefallen ist in der /var/log/message.

Nov 11 02:45:09 routerjb1 kernel: possible SYN flooding on port 4662. Sending cookies.
Nov 11 02:46:09 routerjb1 kernel: possible SYN flooding on port 4662. Sending cookies.

Leider kann ich damit nicht anfangen.

HangLoose
11.11.02, 22:54
moin

das ist quasi eine schutzmaßnahme deines kernels gegen syn flooding

siehe auch /usr/src/linux-2.4.19/Documentation/networking/ip-sysctl.txt


tcp_syncookies - BOOLEAN Only valid when the kernel was compiled with CONFIG_SYNCOOKIES Send out syncookies when the syn backlog queue of a socket overflows. This is to prevent against the common 'syn flood attack' Default: FALSE Note, that syncookies is fallback facility. It MUST NOT be used to help highly loaded servers to stand against legal connection rate. If you see synflood warnings in your logs, but investigation shows that they occur because of overload with legal connections, you should tune another parameters until this warning disappear. See: tcp_max_syn_backlog, tcp_synack_retries, tcp_abort_on_overflow. syncookies seriously violate TCP protocol, do not allow to use TCP extensions, can result in serious degradation of some services (f.e. SMTP relaying), visible not by you, but your clients and relays, contacting you. While you see synflood warnings in logs not being really flooded, your server is seriously misconfigured.

Gruß HangLoose