Diffstat (limited to 'Documentation/networking/ip-sysctl.txt')
1 files changed, 59 insertions, 9 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 6f896b9..ca447b3 100644
@@ -48,12 +48,6 @@ min_adv_mss - INTEGER
The advertised MSS depends on the first hop route MTU, but will
never be lower than this setting.
-rt_cache_rebuild_count - INTEGER
- The per net-namespace route cache emergency rebuild threshold.
- Any net-namespace having its route cache rebuilt due to
- a hash bucket chain being too long more than this many times
- will have its route caching disabled
ipfrag_high_thresh - INTEGER
@@ -468,6 +462,19 @@ tcp_syncookies - BOOLEAN
SYN flood warnings in logs not being really flooded, your server
is seriously misconfigured.
+tcp_fastopen - INTEGER
+ Enable TCP Fast Open feature (draft-ietf-tcpm-fastopen) to send data
+ in the opening SYN packet. To use this feature, the client application
+ must not use connect(). Instead, it should use sendmsg() or sendto()
+ with MSG_FASTOPEN flag which performs a TCP handshake automatically.
+ The values (bitmap) are:
+ 1: Enables sending data in the opening SYN on the client
+ 5: Enables sending data in the opening SYN on the client regardless
+ of cookie availability.
+ Default: 0
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
will be retransmitted. Should not be higher than 255. Default value
@@ -551,6 +558,25 @@ tcp_thin_dupack - BOOLEAN
+tcp_limit_output_bytes - INTEGER
+ Controls TCP Small Queue limit per tcp socket.
+ TCP bulk sender tends to increase packets in flight until it
+ gets losses notifications. With SNDBUF autotuning, this can
+ result in a large amount of packets queued in qdisc/device
+ on the local machine, hurting latency of other flows, for
+ typical pfifo_fast qdiscs.
+ tcp_limit_output_bytes limits the number of bytes on qdisc
+ or device to reduce artificial RTT/cwnd and reduce bufferbloat.
+ Note: For GSO/TSO enabled flows, we try to have at least two
+ packets in flight. Reducing tcp_limit_output_bytes might also
+ reduce the size of individual GSO packet (64KB being the max)
+ Default: 131072
+tcp_challenge_ack_limit - INTEGER
+ Limits number of Challenge ACK sent per second, as recommended
+ in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks)
+ Default: 100
udp_mem - vector of 3 INTEGERs: min, pressure, max
@@ -857,9 +883,19 @@ accept_source_route - BOOLEAN
accept_local - BOOLEAN
- Accept packets with local source addresses. In combination with
- suitable routing, this can be used to direct packets between two
- local interfaces over the wire and have them accepted properly.
+ Accept packets with local source addresses. In combination
+ with suitable routing, this can be used to direct packets
+ between two local interfaces over the wire and have them
+ accepted properly.
+ rp_filter must be set to a non-zero value in order for
+ accept_local to have an effect.
+ default FALSE
+route_localnet - BOOLEAN
+ Do not consider loopback addresses as martian source or destination
+ while routing. This enables the use of 127/8 for local routing purposes.
rp_filter - INTEGER
@@ -1398,6 +1434,20 @@ path_max_retrans - INTEGER
+pf_retrans - INTEGER
+ The number of retransmissions that will be attempted on a given path
+ before traffic is redirected to an alternate transport (should one
+ exist). Note this is distinct from path_max_retrans, as a path that
+ passes the pf_retrans threshold can still be used. Its only
+ deprioritized when a transmission path is selected by the stack. This
+ setting is primarily used to enable fast failover mechanisms without
+ having to reduce path_max_retrans to a very low value. See:
+ for details. Note also that a value of pf_retrans > path_max_retrans
+ disables this feature
+ Default: 0
rto_initial - INTEGER
The initial round trip timeout value in milliseconds that will be used
in calculating round trip times. This is the initial time interval